This is gdbm.info, produced by makeinfo version 6.5 from gdbm.texi. Published by the Free Software Foundation, 51 Franklin Street, Fifth Floor Boston, MA 02110-1301, USA Copyright (C) 1989-1999, 2007-2018 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover, and no Back-Cover texts. A copy of the license is included in the section entitled "GNU Free Documentation License." INFO-DIR-SECTION Programming & development tools START-INFO-DIR-ENTRY * GDBM: (gdbm). The GNU database manager. * gdbm_dump: (gdbm) gdbm_dump. Dump the GDBM database into a flat file. * gdbm_load: (gdbm) gdbm_load. Load the database from a flat file. END-INFO-DIR-ENTRY  File: gdbm.info, Node: Top, Next: Copying, Up: (dir) The GNU database manager. ************************* GNU 'dbm' is a library of functions implementing a hashed database on a disk file. This manual documents GNU 'dbm' Version 1.14.1 ('gdbm'). The software was originally written by Philip A. Nelson. This document was originally written by Pierre Gaumond from texts written by Phil. * Menu: Introduction: * Copying:: Your rights. * Intro:: Introduction to GNU dbm. * List:: List of functions. Functions: * Open:: Opening the database. * Close:: Closing the database. * Count:: Counting records in the database. * Store:: Inserting and replacing records in the database. * Fetch:: Searching records in the database. * Delete:: Removing records from the database. * Sequential:: Sequential access to records. * Reorganization:: Database reorganization. * Sync:: Insure all writes to disk have competed. * Flat files:: Export and import to Flat file format. * Errors:: Error handling. * Recovery:: Recovery from fatal errors. * Options:: Setting internal options. * Locking:: File locking. * Variables:: Useful global variables. * Error codes:: Error codes returned by 'gdbm' calls. * Compatibility:: Compatibility with UNIX dbm and ndbm. Programs * gdbmtool:: Examine and modify a GDBM database. * gdbm_dump:: Dump the database into a flat file. * gdbm_load:: Load the database from a flat file. * gdbmexport:: Export a database into a portable format. * Exit codes:: Exit codes returned by GDBM utilities. Other topics: * Bugs:: Problems and bugs. * Resources:: Additional resources, * GNU Free Documentation License:: Document license. * Index:: Index  File: gdbm.info, Node: Copying, Next: Intro, Prev: Top, Up: Top 1 Copying Conditions. ********************* This library is "free"; this means that everyone is free to use it and free to redistribute it on a free basis. GNU 'dbm' ('gdbm') is not in the public domain; it is copyrighted and there are restrictions on its distribution, but these restrictions are designed to permit everything that a good cooperating citizen would want to do. What is not allowed is to try to prevent others from further sharing any version of 'gdbm' that they might get from you. Specifically, we want to make sure that you have the right to give away copies 'gdbm', that you receive source code or else can get it if you want it, that you can change these functions or use pieces of them in new free programs, and that you know you can do these things. To make sure that everyone has such rights, we have to forbid you to deprive anyone else of these rights. For example, if you distribute copies 'gdbm', you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must tell them their rights. Also, for our own protection, we must make certain that everyone finds out that there is no warranty for anything in the 'gdbm' distribution. If these functions are modified by someone else and passed on, we want their recipients to know that what they have is not what we distributed, so that any problems introduced by others will not reflect on our reputation. 'Gdbm' is currently distributed under the terms of the GNU General Public License, Version 3. (_NOT_ under the GNU General Library Public License.) A copy the GNU General Public License is included with the distribution of 'gdbm'.  File: gdbm.info, Node: Intro, Next: List, Prev: Copying, Up: Top 2 Introduction to GNU 'dbm'. **************************** GNU 'dbm' ('gdbm') is a library of database functions that use extensible hashing and works similar to the standard UNIX 'dbm' functions. These routines are provided to a programmer needing to create and manipulate a hashed database. ('gdbm' is _NOT_ a complete database package for an end user.) The basic use of 'gdbm' is to store key/data pairs in a data file. Each key must be unique and each key is paired with only one data item. The keys can not be directly accessed in sorted order. The basic unit of data in 'gdbm' is the structure: typedef struct { char *dptr; int dsize; } datum; This structure allows for arbitrary sized keys and data items. The key/data pairs are stored in a 'gdbm' disk file, called a 'gdbm' database. An application must open a 'gdbm' database to be able manipulate the keys and data contained in the database. 'gdbm' allows an application to have multiple databases open at the same time. When an application opens a 'gdbm' database, it is designated as a 'reader' or a 'writer'. A 'gdbm' database can be opened by at most one writer at a time. However, many readers may open the database simultaneously. Readers and writers can not open the 'gdbm' database at the same time.  File: gdbm.info, Node: List, Next: Open, Prev: Intro, Up: Top 3 List of functions. ******************** The following is a quick list of the functions contained in the 'gdbm' library. The include file 'gdbm.h', that can be included by the user, contains a definition of these functions. #include GDBM_FILE gdbm_open(name, block_size, flags, mode, fatal_func); void gdbm_close(dbf); int gdbm_store(dbf, key, content, flag); datum gdbm_fetch(dbf, key); int gdbm_delete(dbf, key); datum gdbm_firstkey(dbf); datum gdbm_nextkey(dbf, key); int gdbm_reorganize(dbf); void gdbm_sync(dbf); int gdbm_exists(dbf, key); char *gdbm_strerror(errno); int gdbm_setopt(dbf, option, value, size); int gdbm_fdesc(dbf); int gdbm_export (GDBM_FILE, const char *, int, int); int gdbm_export_to_file (GDBM_FILE dbf, FILE *fp); int gdbm_import (GDBM_FILE, const char *, int); int gdbm_import_from_file (GDBM_FILE dbf, FILE *fp, int flag); int gdbm_count (GDBM_FILE dbf, gdbm_count_t *pcount); int gdbm_version_cmp (int const a[], int const b[]); The 'gdbm.h' include file is often in the '/usr/include' directory. (The actual location of 'gdbm.h' depends on your local installation of 'gdbm'.)  File: gdbm.info, Node: Open, Next: Close, Prev: List, Up: Top 4 Opening the database. *********************** -- gdbm interface: GDBM_FILE gdbm_open (const char *NAME, int BLOCK_SIZE, int FLAGS, int MODE, void (*fatal_func)(const char *)) Initializes 'gdbm' system. If the file has a size of zero bytes, a file initialization procedure is performed, setting up the initial structure in the file. The arguments are: NAME The name of the file (the complete name, 'gdbm' does not append any characters to this name). BLOCK_SIZE It is used during initialization to determine the size of various constructs. It is the size of a single transfer from disk to memory. This parameter is ignored if the file has been previously initialized. If the value is less than 512, the file system block size is used instead. The size is adjusted so that the block can hold exact number of directory entries, so that the effective block size can be slightly greater than requested. However, if the 'GDBM_BSEXACT' flag is set and the size needs to be adjusted, the function will return with error status, setting the 'gdbm_errno' variable to 'GDBM_BLOCK_SIZE_ERROR'. FLAGS If 'flags' is set to 'GDBM_READER', the user wants to just read the database and any call to 'gdbm_store' or 'gdbm_delete' will fail. Many readers can access the database at the same time. If 'flags' is set to 'GDBM_WRITER', the user wants both read and write access to the database and requires exclusive access. If 'flags' is set to 'GDBM_WRCREAT', the user wants both read and write access to the database and wants it created if it does not already exist. If 'flags' is set to 'GDBM_NEWDB', the user want a new database created, regardless of whether one existed, and wants read and write access to the new database. The following may also be logically or'd into the database flags: 'GDBM_SYNC', which causes all database operations to be synchronized to the disk, 'GDBM_NOLOCK', which prevents the library from performing any locking on the database file, and 'GDBM_NOMMAP', which disables the memory mapping mechanism. The option 'GDBM_FAST' is now obsolete, since 'gdbm' defaults to no-sync mode. If this flag is set and the requested BLOCK_SIZE cannot be used without adjustment, 'gdbm_open' will refuse to create the databases. In this case it will set the 'gdbm_errno' variable to 'GDBM_BLOCK_SIZE_ERROR' and return 'NULL'. If the host 'open' call (*note (open(2))open::) supports the 'O_CLOEXEC' flag, the 'GDBM_CLOEXEC' can be or'd into the flags, to enable the close-on-exec flag for the database file descriptor. MODE File mode (see *note change permissions of a file: (chmod(2))chmod, and *note open a file: (open(2))open.), which is used if the file is created). FATAL_FUNC A function for 'gdbm' to call if it detects a fatal error. The only parameter of this function is a string. If the value of 'NULL' is provided, 'gdbm' will use a default function. The return value, is the pointer needed by all other functions to access that 'gdbm' file. If the return is the 'NULL' pointer, 'gdbm_open' was not successful. The errors can be found in 'gdbm_errno' variable (*note gdbm_errno: Variables.). Available error codes are discussed in *note Error codes::. In all of the following calls, the parameter DBF refers to the pointer returned from 'gdbm_open'. -- gdbm interface: GDBM_FILE gdbm_fd_open (int FD, const char *NAME, int BLOCK_SIZE, int FLAGS, int MODE, void (*fatal_func)(const char *)) Alternative function for opening a GDBM database. The FD argument is the file descriptor of the database file obtained by a call to 'open'(2), 'creat'(2) or similar funcionss. The descriptor is not dup'ed, and will be closed when the returned GDBM_FILE is closed. Use 'dup'(2) if that is not desirable. -- gdbm interface: int gdbm_copy_meta (GDBM_FILE DST, GDBM_FILE SRC) Copy file ownership and mode from SRC to DST.  File: gdbm.info, Node: Close, Next: Count, Prev: Open, Up: Top 5 Closing the database. *********************** It is important that every file opened is also closed. This is needed to update the reader/writer count on the file: -- gdbm interface: void gdbm_close (GDBM_FILE DBF) This function closes the 'gdbm' file and frees all memory associated with it. The parameter is: DBF The pointer returned by 'gdbm_open'.  File: gdbm.info, Node: Count, Next: Store, Prev: Close, Up: Top 6 Number of Records ******************* -- gdbm interface: int gdbm_count (GDBM_FILE DBF, gdbm_count_t *PCOUNT) Counts number of records in the database DBF. On success, stores it in the memory location pointed to by PCOUNT and return 0. On error, sets 'gdbm_errno' (if relevant, also 'errno') and returns -1.  File: gdbm.info, Node: Store, Next: Fetch, Prev: Count, Up: Top 7 Inserting and replacing records in the database. ************************************************** -- gdbm interface: int gdbm_store (GDBM_FILE DBF, datum KEY, datum CONTENT, int FLAG) The function 'gdbm_store' inserts or replaces records in the database. The parameters are: DBF The pointer returned by 'gdbm_open'. KEY The search key. CONTENT The data to be associated with the key. FLAG Defines the action to take when the key is already in the database. The value 'GDBM_REPLACE' (defined in 'gdbm.h') asks that the old data be replaced by the new CONTENT. The value 'GDBM_INSERT' asks that an error be returned and no action taken if the KEY already exists. This function can return the following values: -1 The item was not stored in the database because the caller was not an official writer or either KEY or CONTENT have a 'NULL' 'dptr' field. Both KEY and CONTENT must have the 'dptr' field be a non-'NULL' value. Since a 'NULL' 'dptr' field is used by other functions to indicate an error, it cannot be valid data. +1 The item was not stored because the argument FLAG was 'GDBM_INSERT' and the KEY was already in the database. 0 No error. The value of CONTENT is keyed by KEY. The file on disk is updated to reflect the structure of the new database before returning from this function. If you store data for a KEY that is already in the data base, 'gdbm' replaces the old data with the new data if called with 'GDBM_REPLACE'. You do not get two data items for the same 'key' and you do not get an error from 'gdbm_store'. The size in 'gdbm' is not restricted like 'dbm' or 'ndbm'. Your data can be as large as you want.  File: gdbm.info, Node: Fetch, Next: Delete, Prev: Store, Up: Top 8 Searching for records in the database. **************************************** -- gdbm interface: datum gdbm_fetch (GDBM_FILE DBF, datum KEY) Looks up a given KEY and returns the information associated with it. The 'dptr' field in the structure that is returned points to a memory block allocated by 'malloc'. It is the caller's responsibility to free it when no longer needed. If the 'dptr' is 'NULL', inspect the value of the 'gdbm_errno' variable (*note gdbm_errno: Variables.). If it is 'GDBM_ITEM_NOT_FOUND', no data was found. Any other value means an error occurred. Use 'gdbm_strerror' function to convert 'gdbm_errno' to a human-readable string. The parameters are: DBF The pointer returned by 'gdbm_open'. KEY The search key. An example of using this function: content = gdbm_fetch (dbf, key); if (content.dptr == NULL) { fprintf(stderr, "key not found\n"); } else { /* do something with content.dptr */ } You may also search for a particular key without retrieving it: -- gdbm interface: int gdbm_exists (GDBM_FILE DBF, datum KEY) Checks whether the KEY exists in the database DBF. If KEY is found, returns 'true' ('1'). If it is not found, returns 'false' ('0') and sets 'gdbm_errno' to 'GDBM_NO_ERROR' ('0'). On error, returns '0' and sets 'gdbm_errno' to a non-'0' error code. The parameters are: DBF The pointer returned by 'gdbm_open'. KEY The search key.  File: gdbm.info, Node: Delete, Next: Sequential, Prev: Fetch, Up: Top 9 Removing records from the database. ************************************* To remove some data from the database, use the 'gdbm_delete' function. -- gdbm interface: int gdbm_delete (GDBM_FILE DBF, datum KEY) Deletes the data associated with the given KEY, if it exists in the database DBF. The file on disk is updated to reflect the structure of the new database before returning from this function. The parameters are: DBF The pointer returned by 'gdbm_open'. DATUM KEY The search key. The function returns '-1' if the item is not present or the requester is a reader. The return of '0' marks a successful delete.  File: gdbm.info, Node: Sequential, Next: Reorganization, Prev: Delete, Up: Top 10 Sequential access to records. ******************************** The next two functions allow for accessing all items in the database. This access is not 'key' sequential, but it is guaranteed to visit every 'key' in the database once. The order has to do with the hash values. 'gdbm_firstkey' starts the visit of all keys in the database. 'gdbm_nextkey' finds and reads the next entry in the hash structure for 'dbf'. -- gdbm interface: datum gdbm_firstkey (GDBM_FILE DBF) Initiate sequential access to the database DBF. The returned value is the first key accessed in the database. If the 'dptr' field in the returned datum is 'NULL', inspect the 'gdbm_errno' variable (*note gdbm_errno: Variables.). The value of 'GDBM_ITEM_NOT_FOUND' means that the database contains no data. Other value means an error occurred. Otherwise, 'dptr' points to a memory block obtained from 'malloc', which holds the key value. The caller is responsible for freeing this memory block when no longer needed. -- gdbm interface: datum gdbm_nextkey (GDBM_FILE DBF, datum PREV) This function continues the iteration over the keys in DBF, initiated by 'gdbm_firstkey'. The parameter PREV holds the value returned from a previous call to 'gdbm_nextkey' or 'gdbm_firstkey'. The function returns next key from the database. If the 'dptr' field in the returned datum is 'NULL' inspect the 'gdbm_errno' variable (*note gdbm_errno: Variables.). The value of 'GDBM_ITEM_NOT_FOUND' means that all keys in the database has been visited. Any other value means an error occurred. Otherwise, 'dptr' points to a memory block obtained from 'malloc', which holds the key value. The caller is responsible for freeing this memory block when no longer needed. These functions were intended to visit the database in read-only algorithms, for instance, to validate the database or similar operations. The usual algorithm for sequential access is: key = gdbm_firstkey (dbf); while (key.dptr) { datum nextkey; /* do something with the key */ ... /* Obtain the next key */ nextkey = gdbm_nextkey (dbf, key); /* Reclaim the memory used by the key */ free (key.dptr); /* Use nextkey in the next iteration. */ key = nextkey; } Care should be taken when the 'gdbm_delete' function is used in such a loop. File visiting is based on a "hash table". The 'gdbm_delete' function re-arranges the hash table to make sure that any collisions in the table do not leave some item "un-findable". The original key order is _not_ guaranteed to remain unchanged in all instances. So it is possible that some key will not be visited if a loop like the following is executed: key = gdbm_firstkey (dbf); while (key.dptr) { datum nextkey; if (some condition) { gdbm_delete (dbf, key); } nextkey = gdbm_nextkey (dbf, key); free (key.dptr); key = nextkey; }  File: gdbm.info, Node: Reorganization, Next: Sync, Prev: Sequential, Up: Top 11 Database reorganization. *************************** The following function should be used very seldom. -- gdbm interface: int gdbm_reorganize (GDBM_FILE DBF) Reorganizes the database. The parameter is: DBF The pointer returned by 'gdbm_open'. If you have had a lot of deletions and would like to shrink the space used by the 'gdbm' file, this function will reorganize the database. This results, in particular, in shortening the length of a 'gdbm' file by removing the space occupied by deleted records. This reorganization requires creating a new file and inserting all the elements in the old file DBF into the new file. The new file is then renamed to the same name as the old file and DBF is updated to contain all the correct information about the new file. If an error is detected, the return value is negative. The value zero is returned after a successful reorganization.  File: gdbm.info, Node: Sync, Next: Flat files, Prev: Reorganization, Up: Top 12 Database Synchronization *************************** Unless your database was opened with the 'GDBM_SYNC' flag, 'gdbm' does not wait for writes to be flushed to the disk before continuing. This allows for faster writing of databases at the risk of having a corrupted database if the application terminates in an abnormal fashion. The following function allows the programmer to make sure the disk version of the database has been completely updated with all changes to the current time. -- gdbm interface: void gdbm_sync (GDBM_FILE DBF) Synchronizes the changes in DBF with its disk file. The parameter is a pointer returned by 'gdbm_open'. This function would usually be called after a complete set of changes have been made to the database and before some long waiting time. The 'gdbm_close' function automatically calls the equivalent of 'gdbm_sync' so no call is needed if the database is to be closed immediately after the set of changes have been made.  File: gdbm.info, Node: Flat files, Next: Errors, Prev: Sync, Up: Top 13 Export and Import ******************** 'Gdbm' databases can be converted into so-called "flat format" files. Such files cannot be used for searching, their sole purpose is to keep the data from the database for restoring it when the need arrives. There are two flat file formats, which differ in the way they represent the data and in the amount of meta-information stored. Both formats can be used, for example, to migrate between the different versions of 'gdbm' databases. Generally speaking, flat files are safe to send over the network, and can be used to recreate the database on another machine. The recreated database is guaranteed to be a byte-to-byte equivalent of the database from which the flat file was created. This does not necessarily mean, however, that this file can be used in the same way as the original one. For example, if the original database contained non-ASCII data (e.g. C structures, integers etc.), the recreated database can be of any use only if the target machine has the same integer size and byte ordering as the source one and if its C compiler uses the same packing conventions as the one which generated C which populated the original database. In general, such binary databases are not portable between machines, unless you follow some stringent rules on what data is written to them and how it is interpreted. The GDBM version 1.14.1 supports two flat file formats. The "binary" flat file format was first implemented in GDBM version 1.9.1. This format stores only key/data pairs, it does not keep information about the database file itself. As its name implies, files in this format are binary files. The "ascii" flat file format encodes all data in base64 and stores not only key/data pairs, but also the original database file metadata, such as file name, mode and ownership. Files in this format can be sent without additional encapsulation over transmission channels that normally allow only ASCII data, such as, e.g. SMTP. Due to additional metadata they allow for restoring an exact copy of the database, including file ownership and privileges, which is especially important if the database in question contained some security-related data. We call a process of creating a flat file from a database "exporting" or "dumping" this database. The reverse process, creating the database from a flat file is called "importing" or "loading" the database. -- gdbm interface: int gdbm_dump (GDBM_FILE DBF, const char *FILENAME, int FORMAT, int OPEN_FLAGS, int MODE) Dumps the database file to the named file in requested format. Arguments are: DBF A pointer to the source database, returned by a prior call to 'gdbm_open'. FILENAME Name of the dump file. FORMAT Output file format. Allowed values are: 'GDBM_DUMP_FMT_BINARY' to create a binary dump and 'GDBM_DUMP_FMT_ASCII' to create an ASCII dump file. OPEN_FLAGS How to create the output file. If FLAG is 'GDBM_WRCREAT' the file will be created if it does not exist. If it does exist, the 'gdbm_dump' will fail. If FLAG is 'GDBM_NEWDB', the function will create a new output file, replacing it if it already exists. MODE The permissions to use when creating the output file. See *note open a file: (open(2))open, for a detailed discussion. -- gdbm interface: int gdbm_load (GDBM_FILE *PDBF, const char *FILENAME, int FLAG, int META_MASK, unsigned long *ERRLINE) Loads data from the dump file FILENAME into the database pointed to by PDBF. The latter can point to 'NULL', in which case the function will try to create a new database. If it succeeds, the function will return, in the memory location pointed to by PDBF, a pointer to the newly created database. If the dump file carries no information about the original database file name, the function will set 'gdbm_errno' to 'GDBM_NO_DBNAME' and return '-1', indicating failure. The FLAG has the same meaning as the FLAG argument to the 'gdbm_store' function (*note Store::). The META_MASK argument can be used to disable restoring certain bits of file's meta-data from the information in the input dump file. It is a binary OR of zero or more of the following: GDBM_META_MASK_MODE Do not restore file mode. GDBM_META_MASK_OWNER Do not restore file owner. The function returns 0 upon successful completion or -1 on fatal errors and 1 on mild (non-fatal) errors. If a fatal error occurs, 'gdbm_errno' will be set to one of the following values: GDBM_FILE_OPEN_ERROR Input file (FILENAME) cannot be opened. The 'errno' variable can be used to get more detail about the failure. GDBM_MALLOC_ERROR Not enough memory to load data. GDBM_FILE_READ_ERROR Reading from FILENAME failed. The 'errno' variable can be used to get more detail about the failure. GDBM_ILLEGAL_DATA Input contained some illegal data. GDBM_ITEM_NOT_FOUND This error can occur only when the input file is in ASCII format. It indicates that the data part of the record about to be read lacked length specification. Application developers are advised to treat this error equally as 'GDBM_ILLEGAL_DATA'. Mild errors mean that the function was able to successfully load and restore the data, but was unable to change database file metadata afterward. The table below lists possible values for 'gdbm_errno' in this case. To get more detail, inspect the system 'errno' variable. GDBM_ERR_FILE_OWNER The function was unable to restore database file owner. GDBM_ERR_FILE_MODE The function was unable to restore database file mode (permission bits). If an error occurs while loading data from an input file in ASCII format, the number of line in which the error occurred will be stored in the location pointed to by the ERRLINE parameter, unless it is 'NULL'. If the line information is not available or applicable, ERRLINE will be set to '0'. -- gdbm interface: int gdbm_dump_to_file (GDBM_FILE DBF, FILE *FP, int FORMAT) This is an alternative entry point to 'gdbm_dump' (which see). Arguments are: DBF A pointer to the source database, returned by a call to 'gdbm_open'. FP File to write the data to. FORMAT Format of the dump file. See the FORMAT argument to the 'gdbm_dump' function. -- gdbm interface: int gdbm_load_from_file (GDBM_FILE *PDBF, FILE *FP, int REPLACE, int META_MASK, unsigned long *LINE) This is an alternative entry point to 'gdbm_dump'. It writes the output to FP which must be a file open for writing. The rest of arguments is the same as for 'gdbm_load' (excepting of course FLAG, which is not needed in this case). -- gdbm interface: int gdbm_export (GDBM_FILE DBF, const char *EXPORTFILE, int FLAG, int MODE) This function is retained for compatibility with GDBM 1.10 and earlier. It dumps the database to a file in binary dump format and is entirely equivalent to gdbm_dump(DBF, EXPORTFILE, GDBM_DUMP_FMT_BINARY, FLAG, MODE) -- gdbm interface: int gdbm_export_to_file (GDBM_FILE DBF, FILE *FP) This is an alternative entry point to 'gdbm_export'. This function writes to file FP a binary dump of the database DBF. -- gdbm interface: int gdbm_import (GDBM_FILE DBF, const char *IMPORTFILE, int FLAG) This function is retained for compatibility with GDBM 1.10 and earlier. It loads the file IMPORTFILE, which must be a binary flat file, into the database DBF and is equivalent to the following construct: DBF = gdbm_open (IMPORTFILE, 0, FLAG == GDBM_REPLACE ? GDBM_WRCREAT : GDBM_NEWDB, 0600, NULL); gdbm_load (&DBF, EXPORTFILE, 0, FLAG, NULL) -- gdbm interface: int gdbm_import_from_file (GDBM_FILE DBF, FILE *FP, int FLAG) An alternative entry point to 'gdbm_import'. Reads the binary dump from the file FP and stores the key/value pairs to DBF. *Note Store::, for a description of FLAG. This function is equivalent to: DBF = gdbm_open (IMPORTFILE, 0, FLAG == GDBM_REPLACE ? GDBM_WRCREAT : GDBM_NEWDB, 0600, NULL); gdbm_load_from_file (DBF, FP, FLAG, 0, NULL);  File: gdbm.info, Node: Errors, Next: Recovery, Prev: Flat files, Up: Top 14 Error handling. ****************** The global variable 'gdbm_errno' (*note gdbm_errno: Variables.) keeps the error code of the most recent error encountered by GDBM functions. To convert this code to human-readable string, use the following function: -- gdbm interface: const char * gdbm_strerror (gdbm_error ERRNO) Converts ERRNO (which is an integer value) into a human-readable descriptive text. Returns a pointer to a static string. The caller must not alter or free the returned pointer. Detailed information about the most recent error that occurred while operating on a GDBM file is stored in the 'GDBM_FILE' object itself. To retrieve it, the following functions are provided: -- gdbm interface: gdbm_error gdbm_last_errno (GDBM_FILE DBF) Returns the code of the most recent error encountered when operating on DBF. -- gdbm interface: int gdbm_last_syserr (GDBM_FILE DBF) Returns the value of the system 'errno' variable associated with the most recent error. Notice, that not all GDBM errors have an associated system error code. The following are the ones that have: * GDBM_FILE_OPEN_ERROR * GDBM_FILE_WRITE_ERROR * GDBM_FILE_SEEK_ERROR * GDBM_FILE_READ_ERROR * GDBM_FILE_STAT_ERROR * GDBM_BACKUP_FAILED For other errors, 'gdbm_last_syserr' will return 0. -- gdbm interface: int gdbm_check_syserr (gdbm_errno ERR) Returns '1', if system errno value should be checked to get more info on the error described by GDBM code ERR. To get a human-readable description of the recent error for a particular database file, use the 'gdbm_db_strerror' function: -- gdbm interface: const char * gdbm_db_strerror (GDBM_FILE DBF) Returns textual description of the most recent error encountered when operating on the database DBF. The resulting string is often more informative than what would be returned by 'gdbm_strerror(gdbm_last_errno(DBF))'. In particular, if there is a system error associated with the recent failure, it will be described as well. -- gdbm interface: void gdbm_clear_error (GDBM_FILE DBF) Clears the error state for the database DBF. Normally, this function is called upon the entry to any GDBM function. Certain errors (such as write error when saving stored key) can leave database file in inconistent state. When such a critical error occurs, the database file is marked as needing recovery. Subsequent calls to any GDBM functions for that database file (except 'gdbm_recover'), will return immediately with GDBM error value 'GDBM_NEED_RECOVERY'. Additionally, the following function can be used to check the state of the database file: -- gdbm interface: int gdbm_needs_recovery (GDBM_FILE DBF) Returns '1' if the database file DBF is in inconsistent state and needs recovery. The only way to bring the database back to operational state is to call the 'gdbm_recover' function (*note Recovery::).  File: gdbm.info, Node: Recovery, Next: Options, Prev: Errors, Up: Top 15 Recovery *********** Certain errors (such as write error when saving stored key) can leave database file in "inconistent state". When such a critical error occurs, the database file is marked as needing recovery. Subsequent calls to any GDBM functions for that database file (except 'gdbm_recover'), will return immediately with GDBM error value 'GDBM_NEED_RECOVERY'. To escape from this state and bring the database back to operational state, use the following function: -- gdbm interface: int gdbm_recover (GDBM_FILE DBF, gdbm_recovery *RCVR, int FLAGS) Check the database file DBF and fix eventual errors. The RCVR argument points to a structure that has "input members", providing additional information to alter the behavior of 'gdbm_recover', and "output members", used to return additional statistics about the recovery process (RCVR can be 'NULL' if no such information is needed). Each input member has a corresponding flag bit, which must be set in the FLAGS in order to instruct the function to use it. The 'gdbm_recover' type is defined as: typedef struct gdbm_recovery_s { /* Input members. These are initialized before call to gdbm_recover. The flags argument specifies which of them are initialized. */ void (*errfun) (void *data, char const *fmt, ...); void *data; size_t max_failed_keys; size_t max_failed_buckets; size_t max_failures; /* Output members. The gdbm_recover function fills these before returning. */ size_t recovered_keys; size_t recovered_buckets; size_t failed_keys; size_t failed_buckets; char *backup_name; } gdbm_recovery; The "input members" modify the behavior of 'gdbm_recover': -- input member on gdbm_recovery: void (*errfun) (void *DATA, char const *FMT, ...) If the 'GDBM_RCVR_ERRFUN' flag bit is set, 'errfun' points to a function that will be called upon each recoverable or non-fatal error that occurred during the recovery. -- input member of gdbm_recovery: void * data Supplies first argument for the 'errfun' invocations. -- input member of gdbm_recovery: size_t max_failed_keys If 'GDBM_RCVR_MAX_FAILED_KEYS' is set, this member sets the limit on the number of keys that cannot be retrieved. If the number of failed keys grows bigger than 'max_failed_keys', recovery is aborted and error is returned. -- input member of gdbm_recovery: size_t max_failed_buckets If 'GDBM_RCVR_MAX_FAILED_BUCKETS' is set, this member sets the limit on the number of buckets that cannot be retrieved or that contain bogus information. If the number of failed buckets grows bigger than 'max_failed_buckets', recovery is aborted and error is returned. -- output member of gdbm_recovery: size_t max_failures If 'GDBM_RCVR_MAX_FAILURES' is set, this member sets the limit of failures that are tolerated during recovery. If the number of errors grows bigger than 'max_failures', recovery is aborted and error is returned. The following members are filled on output, upon successful return from the function: -- output member of gdbm_recovery: size_t recovered_keys Number of recovered keys. -- output member of gdbm_recovery: size_t recovered_buckets Number of recovered buckets. -- output member of gdbm_recovery: size_t failed_keys Number of key/data pairs that cannot be retrieved. -- output member of gdbm_recovery: size_t failed_buckets Number of buckets that cannot be retrieved. -- output member of gdbm_recovery: char * backup_name Name of the file keeping the copy of the original database, in the state prior to recovery. It is filled if the GDBM_RCVR_BACKUP flag is set. The string is allocated using the 'malloc' call. The caller is responsible for freeing that memory when no longer needed. By default, 'gdbm_recovery' first checks the database fo inconsistencies and attempts recovery only if some were found. The special flag bit 'GDBM_RCVR_FORCE' instructs 'gdbm_recovery' to omit this check and to force recovery unconditionally.  File: gdbm.info, Node: Options, Next: Locking, Prev: Recovery, Up: Top 16 Setting options ****************** 'Gdbm' supports the ability to set certain options on an already open database. -- gdbm interface: int gdbm_setopt (GDBM_FILE DBF, int OPTION, void *VALUE, int SIZE) Sets an option on the database or returns the value of an option. The parameters are: DBF The pointer returned by 'gdbm_open'. OPTION The option to be set or retrieved. VALUE A pointer to the value to which OPTION will be set or where to place the option value (depending on the option). SIZE The length of the data pointed to by VALUE. The valid options are: GDBM_SETCACHESIZE GDBM_CACHESIZE Set the size of the internal bucket cache. This option may only be set once on each GDBM_FILE descriptor, and is set automatically to 100 upon the first access to the database. The VALUE should point to a 'size_t' holding the desired cache size. The 'GDBM_CACHESIZE' option is provided for compatibility with earlier versions. GDBM_GETCACHESIZE Return the size of the internal bucket cache. The VALUE should point to a 'size_t' variable, where the size will be stored. GDBM_GETFLAGS Return the flags describing the state of the database. The VALUE should point to a 'int' variable where to store the flags. The return is the same as the flags used when opening the database (*note gdbm_open: Open.), except that it reflects the current state (which may have been altered by another calls to 'gdbm_setopt'. GDBM_FASTMODE Enable or disable the "fast writes mode", i.e. writes without subsequent synchronization. The VALUE should point to an integer: 'TRUE' to enable fast mode, and 'FALSE' to disable it. This option is retained for compatibility with previous versions of 'gdbm'. Its effect is the reverse of 'GDBM_SETSYNCMODE' (see below). GDBM_SETSYNCMODE GDBM_SYNCMODE Turn on or off file system synchronization operations. This setting defaults to off. The VALUE should point to an integer: 'TRUE' to turn synchronization on, and 'FALSE' to turn it off. Note, that this option is a reverse of 'GDBM_FASTMODE', i.e. calling 'GDBM_SETSYNCMODE' with 'TRUE' has the same effect as calling 'GDBM_FASTMODE' with 'FALSE'. The 'GDBM_SYNCMODE' option is provided for compatibility with earlier versions. GDBM_GETSYNCMODE Return the current synchronization status. The VALUE should point to an 'int' where the status will be stored. GDBM_SETCENTFREE GDBM_CENTFREE _NOTICE: This feature is still under study._ Set central free block pool to either on or off. The default is off, which is how previous versions of 'gdbm' handled free blocks. If set, this option causes all subsequent free blocks to be placed in the _global_ pool, allowing (in theory) more file space to be reused more quickly. The VALUE should point to an integer: 'TRUE' to turn central block pool on, and 'FALSE' to turn it off. The 'GDBM_CENTFREE' option is provided for compatibility with earlier versions. GDBM_SETCOALESCEBLKS GDBM_COALESCEBLKS _NOTICE: This feature is still under study._ Set free block merging to either on or off. The default is off, which is how previous versions of 'gdbm' handled free blocks. If set, this option causes adjacent free blocks to be merged. This can become a CPU expensive process with time, though, especially if used in conjunction with GDBM_CENTFREE. The VALUE should point to an integer: 'TRUE' to turn free block merging on, and 'FALSE' to turn it off. GDBM_GETCOALESCEBLKS Return the current status of free block merging. The VALUE should point to an 'int' where the status will be stored. GDBM_SETMAXMAPSIZE Sets maximum size of a memory mapped region. The VALUE should point to a value of type 'size_t', 'unsigned long' or 'unsigned'. The actual value is rounded to the nearest page boundary (the page size is obtained from 'sysconf(_SC_PAGESIZE)'). GDBM_GETMAXMAPSIZE Return the maximum size of a memory mapped region. The VALUE should point to a value of type 'size_t' where to return the data. GDBM_SETMMAP Enable or disable memory mapping mode. The VALUE should point to an integer: 'TRUE' to enable memory mapping or 'FALSE' to disable it. GDBM_GETMMAP Check whether memory mapping is enabled. The VALUE should point to an integer where to return the status. GDBM_GETDBNAME Return the name of the database disk file. The VALUE should point to a variable of type 'char**'. A pointer to the newly allocated copy of the file name will be placed there. The caller is responsible for freeing this memory when no longer needed. For example: char *name; if (gdbm_setopt (dbf, GDBM_GETDBNAME, &name, sizeof (name))) { fprintf (stderr, "gdbm_setopt failed: %s\n", gdbm_strerror (gdbm_errno)); } else { printf ("database name: %s\n", name); free (name); } GDBM_GETBLOCKSIZE Return the block size in bytes. The VALUE should point to 'int'. The return value will be '-1' upon failure, or '0' upon success. The global variable 'gdbm_errno' will be set upon failure. For instance, to set a database to use a cache of 10, after opening it with 'gdbm_open', but prior to accessing it in any way, the following code could be used: int value = 10; ret = gdbm_setopt (dbf, GDBM_CACHESIZE, &value, sizeof (int));  File: gdbm.info, Node: Locking, Next: Variables, Prev: Options, Up: Top 17 File Locking. **************** With locking disabled (if 'gdbm_open' was called with 'GDBM_NOLOCK'), the user may want to perform their own file locking on the database file in order to prevent multiple writers operating on the same file simultaneously. In order to support this, the 'gdbm_fdesc' routine is provided. -- gdbm interface: int gdbm_fdesc (GDBM_FILE DBF) Returns the file descriptor of the database DBF. This value can be used as an argument to 'flock', 'lockf' or similar calls.  File: gdbm.info, Node: Variables, Next: Error codes, Prev: Locking, Up: Top 18 Useful global variables. *************************** The following global variables and constants are available: -- Variable: gdbm_error gdbm_errno This variable contains error code from the last failed 'gdbm' call. *Note Error codes::, for a list of available error codes and their descriptions. Use 'gdbm_strerror' (*note Errors::) to convert it to a descriptive text. -- Variable: const char * gdbm_errlist[] This variable is an array of error descriptions, which is used by 'gdbm_strerror' to convert error codes to human-readable text (*note Errors::). You can access it directly, if you wish so. It contains '_GDBM_MAX_ERRNO + 1' elements and can be directly indexed by the error code to obtain a corresponding descriptive text. -- Variable: int const gdbm_syserr[] Array of boolean values indicating, for each GDBM error code, whether the value of 'errno'(3) variable is meaningful for this error code. *Note gdbm_check_syserr::. -- Constant: _GDBM_MIN_ERRNO The minimum error code used by 'gdbm'. -- Constant: _GDBM_MAX_ERRNO The maximum error code used by 'gdbm'. -- Variable: const char * gdbm_version A string containing the version information. -- Variable: int const gdbm_version_number[3] This variable contains the 'gdbm' version numbers: Index Meaning ------------------------------------------------------------------- 0 Major number 1 Minor number 2 Patchlevel number Additionally, the following constants are defined in the 'gdbm.h' file: GDBM_VERSION_MAJOR Major number. GDBM_VERSION_MINOR Minor number. GDBM_VERSION_PATCH Patchlevel number. These can be used to verify whether the header file matches the library. To compare two split-out version numbers, use the following function: -- gdbm interface: int gdbm_version_cmp (int const A[3], int const B[3]) Compare two version numbers. Return '-1' if A is less than B, '1' if A is greater than B and '0' if they are equal. Comparison is done from left to right, so that: a = { 1, 8, 3 }; b = { 1, 8, 3 }; gdbm_version_cmp (a, b) => 0 a = { 1, 8, 3 }; b = { 1, 8, 2 }; gdbm_version_cmp (a, b) => 1 a = { 1, 8, 3 }; b = { 1, 9. 0 }; gdbm_version_cmp (a, b) => -1  File: gdbm.info, Node: Error codes, Next: Compatibility, Prev: Variables, Up: Top 19 Error codes ************** This chapter summarizes error codes which can be set by the functions in 'gdbm' library. GDBM_NO_ERROR No error occurred. GDBM_MALLOC_ERROR Memory allocation failed. Not enough memory. GDBM_BLOCK_SIZE_ERROR This error is set by the 'gdbm_open' function (*note Open::), if the value of its BLOCK_SIZE argument is incorrect and the 'GDBM_BSEXACT' flag is set. GDBM_FILE_OPEN_ERROR The library was not able to open a disk file. This can be set by 'gdbm_open' (*note Open::), 'gdbm_export' and 'gdbm_import' functions (*note Flat files::). Inspect the value of the system 'errno' variable to get more detailed diagnostics. GDBM_FILE_WRITE_ERROR Writing to a disk file failed. This can be set by 'gdbm_open' (*note Open::), 'gdbm_export' and 'gdbm_import' functions. Inspect the value of the system 'errno' variable to get more detailed diagnostics. GDBM_FILE_SEEK_ERROR Positioning in a disk file failed. This can be set by 'gdbm_open' (*note Open::) function. Inspect the value of the system 'errno' variable to get a more detailed diagnostics. GDBM_FILE_READ_ERROR Reading from a disk file failed. This can be set by 'gdbm_open' (*note Open::), 'gdbm_export' and 'gdbm_import' functions. Inspect the value of the system 'errno' variable to get a more detailed diagnostics. GDBM_BAD_MAGIC_NUMBER The file given as argument to 'gdbm_open' function is not a valid 'gdbm' file: it has a wrong magic number. GDBM_EMPTY_DATABASE The file given as argument to 'gdbm_open' function is not a valid 'gdbm' file: it has zero length. GDBM_CANT_BE_READER This error code is set by the 'gdbm_open' function if it is not able to lock file when called in 'GDBM_READER' mode (*note GDBM_READER: Open.). GDBM_CANT_BE_WRITER This error code is set by the 'gdbm_open' function if it is not able to lock file when called in writer mode (*note Open::). GDBM_READER_CANT_DELETE Set by the 'gdbm_delete' (*note Delete::) if it attempted to operate on a database that is open in read-only mode (*note GDBM_READER: Open.). GDBM_READER_CANT_STORE Set by the 'gdbm_store' (*note Store::) if it attempted to operate on a database that is open in read-only mode (*note GDBM_READER: Open.). GDBM_READER_CANT_REORGANIZE Set by the 'gdbm_reorganize' (*note Reorganization::) if it attempted to operate on a database that is open in read-only mode (*note GDBM_READER: Open.). GDBM_ITEM_NOT_FOUND Requested item was not found. This error is set by 'gdbm_delete' (*note Delete::) and 'gdbm_fetch' (*note Fetch::) when the requested KEY value is not found in the database. GDBM_REORGANIZE_FAILED The 'gdbm_reorganize' function is not able to create a temporary database. *Note Reorganization::. GDBM_CANNOT_REPLACE Cannot replace existing item. This error is set by the 'gdbm_store' if the requested KEY value is found in the database and the FLAG parameter is not 'GDBM_REPLACE'. *Note Store::, for a detailed discussion. GDBM_ILLEGAL_DATA Either KEY or CONTENT parameter was wrong in a call to to 'gdbm_store' (*note Store::). GDBM_OPT_ALREADY_SET Requested option can be set only once and was already set. This error is returned by the 'gdbm_setopt' function. *Note GDBM_CACHESIZE: Options. GDBM_OPT_ILLEGAL The OPTION argument is not valid or the VALUE argument points to an invalid value in a call to 'gdbm_setopt' function. *Note Options::. GDBM_BYTE_SWAPPED The 'gdbm_open' function (*note Open::) attempts to open a database which is created on a machine with different byte ordering. GDBM_BAD_FILE_OFFSET The 'gdbm_open' function (*note Open::) sets this error code if the file it tries to open has a wrong magic number. GDBM_BAD_OPEN_FLAGS Set by the 'gdbm_export' function if supplied an invalid FLAGS argument. *Note Flat files::. GDBM_FILE_STAT_ERROR Getting information about a disk file failed. The system 'errno' will give more details about the error. This error can be set by the following functions: 'gdbm_open', 'gdbm_reorganize'. GDBM_FILE_EOF End of file was encountered where more data was expected to be present. This error can occur when fetching data from the database and usually means that the database is truncated or otherwise corrupted. This error can be set by any GDBM function that does I/O. Some of these functions are: 'gdbm_delete', 'gdbm_exists', 'gdbm_fetch', 'gdbm_export', 'gdbm_import', 'gdbm_reorganize', 'gdbm_firstkey', 'gdbm_nextkey', 'gdbm_store'. GDBM_NO_DBNAME Output database name is not specified. This error code is set by 'gdbm_load' (*note gdbm_load: gdbm_load function.) if the first argument points to 'NULL' and the input file does not specify the database name. GDBM_ERR_FILE_OWNER This error code is set by 'gdbm_load' if it is unable to restore database file owner. It is a mild error condition, meaning that the data have been restored successfully, only changing the target file owner failed. Inspect the system 'errno' variable to get a more detailed diagnostics. GDBM_ERR_FILE_MODE This error code is set by 'gdbm_load' if it is unable to restore database file mode. It is a mild error condition, meaning that the data have been restored successfully, only changing the target file owner failed. Inspect the system 'errno' variable to get a more detailed diagnostics. GDBM_NEED_RECOVERY Database is in inconsistent state and needs recovery. Call 'gdbm_recover' if you get this error. *Note Recovery::, for a detailed description of recovery functions. GDBM_BACKUP_FAILED The GDBM engine is unable to create backup copy of the file. GDBM_DIR_OVERFLOW Bucket directory would overflow the size limit during an attempt to split hash bucket. This error can occur while storing a new key.  File: gdbm.info, Node: Compatibility, Next: gdbmtool, Prev: Error codes, Up: Top 20 Compatibility with standard 'dbm' and 'ndbm'. ************************************************ 'Gdbm' includes a compatibility layer, which provides traditional 'ndbm' and older 'dbm' functions. The layer is compiled and installed if the '--enable-libgdbm-compat' option is used when configuring the package. The compatibility layer consists of two header files: 'ndbm.h' and 'dbm.h' and the 'libgdbm_compat' library. Older programs using 'ndbm' or 'dbm' interfaces can use 'libgdbm_compat' without any changes. To link a program with the compatibility library, add the following two options to the 'cc' invocation: '-lgdbm -lgdbm_compat'. The '-L' option may also be required, depending on where 'gdbm' is installed, e.g.: cc ... -lgdbm -lgdbm_compat Databases created and manipulated by the compatibility interfaces consist of two different files: 'FILE.dir' and 'FILE.pag'. This is required by the POSIX specification and corresponds to the traditional usage. Note, however, that despite the similarity of the naming convention, actual data stored in these files has not the same format as in the databases created by other 'dbm' or 'ndbm' libraries. In other words, you cannot access a standard UNIX 'dbm' file with GNU 'dbm'! GNU 'dbm' files are not 'sparse'. You can copy them with the usual 'cp' command and they will not expand in the copying process. * Menu: * ndbm:: NDBM interface functions. * dbm:: DBM interface functions.  File: gdbm.info, Node: ndbm, Next: dbm, Up: Compatibility 20.1 NDBM interface functions. ============================== The functions below implement the POSIX 'ndbm' interface: -- ndbm: DBM * dbm_open (char *FILE, int FLAGS, int MODE) Opens a database. The FILE argument is the full name of the database file to be opened. The function opens two files: 'FILE.pag' and 'FILE.dir'. The FLAGS and MODE arguments have the same meaning as the second and third arguments of 'open' (*note open a file: (open(2))open.), except that a database opened for write-only access opens the files for read and write access and the behavior of the 'O_APPEND' flag is unspecified. The function returns a pointer to the 'DBM' structure describing the database. This pointer is used to refer to this database in all operations described below. Any error detected will cause a return value of 'NULL' and an appropriate value will be stored in 'gdbm_errno' (*note Variables::). -- ndbm: void dbm_close (DBM *DBF) Closes the database. The DBF argument must be a pointer returned by an earlier call to 'dbm_open'. -- ndbm: datum dbm_fetch (DBM *DBF, datum KEY) Reads a record from the database with the matching key. The KEY argument supplies the key that is being looked for. If no matching record is found, the 'dptr' member of the returned datum is 'NULL'. Otherwise, the 'dptr' member of the returned datum points to the memory managed by the compatibility library. The application should never free it. -- ndbm: int dbm_store (DBM *DBF, datum KEY, datum CONTENT, int MODE) Writes a key/value pair to the database. The argument DBF is a pointer to the 'DBM' structure returned from a call to 'dbm_open'. The KEY and CONTENT provide the values for the record key and content. The MODE argument controls the behavior of 'dbm_store' in case a matching record already exists in the database. It can have one of the following two values: 'DBM_REPLACE' Replace existing record with the new one. 'DBM_INSERT' The existing record is left unchanged, and the function returns '1'. If no matching record exists in the database, new record will be inserted no matter what the value of the MODE is. -- ndbm: int dbm_delete (DBM *DBF, datum KEY) Deletes the record with the matching key from the database. If the function succeeds, '0' is returned. Otherwise, if no matching record is found or if an error occurs, '-1' is returned. -- ndbm: datum dbm_firstkey (DBM *DBF) Initializes iteration over the keys from the database and returns the first key. Note, that the word 'first' does not imply any specific ordering of the keys. If there are no records in the database, the 'dptr' member of the returned datum is 'NULL'. Otherwise, the 'dptr' member of the returned datum points to the memory managed by the compatibility library. The application should never free it. -- ndbm: datum dbm_nextkey (DBM *DBF) Continues the iteration started by 'dbm_firstkey'. Returns the next key in the database. If the iteration covered all keys in the database, the 'dptr' member of the returned datum is 'NULL'. Otherwise, the 'dptr' member of the returned datum points to the memory managed by the compatibility library. The application should never free it. The usual way of iterating over all the records in the database is: for (key = dbm_firstkey (dbf); key.ptr; key = dbm_nextkey (dbf)) { /* do something with the key */ } The loop above should not try to delete any records from the database, otherwise the iteration is not guaranteed to cover all the keys. *Note Sequential::, for a detailed discussion of this. -- ndbm: int dbm_error (DBM *DBF) Returns the error condition of the database: '0' if no errors occurred so far while manipulating the database, and a non-zero value otherwise. -- ndbm: void dbm_clearerr (DBM *DBF) Clears the error condition of the database. -- ndbm: int dbm_dirfno (DBM *DBF) Returns the file descriptor of the 'dir' file of the database. It is guaranteed to be different from the descriptor returned by the 'dbm_pagfno' function (see below). The application can lock this descriptor to serialize accesses to the database. -- ndbm: int dbm_pagfno (DBM *DBF) Returns the file descriptor of the 'pag' file of the database. See also 'dbm_dirfno'. -- ndbm: int dbm_rdonly (DBM *DBF) Returns '1' if the database DBF is open in a read-only mode and '0' otherwise.  File: gdbm.info, Node: dbm, Prev: ndbm, Up: Compatibility 20.2 DBM interface functions. ============================= The functions below are provided for compatibility with the old UNIX 'DBM' interface. Only one database at a time can be manipulated using them. -- dbm: int dbminit (char *FILE) Opens a database. The FILE argument is the full name of the database file to be opened. The function opens two files: 'FILE.pag' and 'FILE.dir'. If any of them does not exist, the function fails. It never attempts to create the files. The database is opened in the read-write mode, if its disk permissions permit. The application must ensure that the functions described below in this section are called only after a successful call to 'dbminit'. -- dbm: int dbmclose (void) Closes the database opened by an earlier call to 'dbminit'. -- dbm: datum fetch (datum KEY) Reads a record from the database with the matching key. The KEY argument supplies the key that is being looked for. If no matching record is found, the 'dptr' member of the returned datum is 'NULL'. Otherwise, the 'dptr' member of the returned datum points to the memory managed by the compatibility library. The application should never free it. -- dbm: int store (datum KEY, datum CONTENT) Stores the key/value pair in the database. If a record with the matching key already exists, its content will be replaced with the new one. Returns '0' on success and '-1' on error. -- dbm: int delete (datum KEY) Deletes a record with the matching key. If the function succeeds, '0' is returned. Otherwise, if no matching record is found or if an error occurs, '-1' is returned. -- dbm: datum firstkey (void) Initializes iteration over the keys from the database and returns the first key. Note, that the word 'first' does not imply any specific ordering of the keys. If there are no records in the database, the 'dptr' member of the returned datum is 'NULL'. Otherwise, the 'dptr' member of the returned datum points to the memory managed by the compatibility library. The application should never free it. -- dbm: datum nextkey (datum KEY) Continues the iteration started by a call to 'firstkey'. Returns the next key in the database. If the iteration covered all keys in the database, the 'dptr' member of the returned datum is 'NULL'. Otherwise, the 'dptr' member of the returned datum points to the memory managed by the compatibility library. The application should never free it.  File: gdbm.info, Node: gdbmtool, Next: gdbm_dump, Prev: Compatibility, Up: Top 21 Examine and modify a GDBM database. ************************************** The 'gdbmtool' utility allows you to view and modify an existing GDBM database or to create a new one. When invoked without arguments, it tries to open a database file called 'junk.gdbm', located in the current working directory. You can change this default by supplying the name of the database as argument to the program, e.g.: $ gdbmtool file.db The database will be opened in read-write mode, unless the '-r' ('--read-only') option is specified, in which case it will be opened only for reading. If the database does not exist, 'gdbmtool' will create it. There is a special option '-n' ('--newdb', which instructs the utility to create a new database. If it is used and if the database already exists, it will be deleted, so use it sparingly. * Menu: * invocation:: * shell::  File: gdbm.info, Node: invocation, Next: shell, Up: gdbmtool 21.1 gdbmtool invocation ======================== The following table summarizes all 'gdbmtool' command line options: '-b SIZE' '--block-size=SIZE' Set block size. '-c SIZE' '--cache-size=SIZE' Set cache size. '-f FILE' '--file FILE' Read commands from FILE, instead of the standard input. '-h' '--help' Print a concise help summary. '-N' '--norc' Don't read startup files (*note startup files::). '-n' '--newdb' Create the database. '-l' '--no-lock' Disable file locking. '-m' '--no-mmap' Disable mmap. '-q' '--quiet' Don't print the usual welcome banner at startup. This is the same as setting the variable 'quiet' in the startup file. *Note quiet::. '-r' '--read-only' Open the database in read-only mode. '-s' '--synchronize' Synchronize to the disk after each write. '-V' '--version' Print program version and licensing information and exit. '--usage' Print a terse invocation syntax summary along with a list of available command line options.  File: gdbm.info, Node: shell, Prev: invocation, Up: gdbmtool 21.2 gdbmtool interactive mode ============================== After successful startup, 'gdbmtool' starts a loop, in which it reads commands from the standard input, executes them and prints results on the standard output. If the standard input is attached to a console, 'gdbmtool' runs in interactive mode, which is indicated by its "prompt": gdbmtool> _ The utility finishes when it reads the 'quit' command (see below) or detects end-of-file on its standard input, whichever occurs first. A 'gdbmtool' command consists of a "command verb", optionally followed by "arguments", separated by any amount of white space. A command verb can be entered either in full or in an abbreviated form, as long as that abbreviation does not match any other verb. For example, 'co' can be used instead of 'count' and 'ca' instead of 'cache'. Any sequence of non-whitespace characters appearing after the command verb forms an argument. If the argument contains whitespace or unprintable characters it must be enclosed in double quotes. Within double quotes the usual "escape sequences" are understood, as shown in the table below: Sequence Replaced with \a Audible bell character (ASCII 7) \b Backspace character (ASCII 8) \f Form-feed character (ASCII 12) \n Newline character (ASCII 10) \r Carriage return character (ASCII 13) \t Horizontal tabulation character (ASCII 9) \v Vertical tabulation character (ASCII 11) \\ Single slash \" Double quote Table 21.1: Backslash escapes In addition, a backslash immediately followed by the end-of-line character effectively removes that character, allowing to split long arguments over several input lines. Command parameters may be optional or mandatory. If the number of actual arguments is less than the number of mandatory parameters, 'gdbmtool' will prompt you to supply missing arguments. For example, the 'store' command takes two mandatory parameters, so if you invoked it with no arguments, you would be prompted twice to supply the necessary data, as shown in example below: gdbmtool> store key? three data? 3 However, such prompting is possible only in interactive mode. In non-interactive mode (e.g. when running a script), all arguments must be supplied with each command, otherwise 'gdbmtool' will report an error and exit immediately. If the package is compiled with GNU Readline, the input line can be edited (*note Command Line Editing: (readline)Command Line Editing.). * Menu: * variables:: shell variables. * commands:: shell commands. * definitions:: how to define structured data. * startup files::  File: gdbm.info, Node: variables, Next: commands, Up: shell 21.2.1 Shell Variables ---------------------- A number of 'gdbmtool' parameters is kept in its internal variables. -- gdbmtool variable: bool confirm Whether to ask for confirmation before certain destructive operations, such as truncating the existing database. Default is 'true'. -- gdbmtool variable: string ps1 Primary prompt string. Its value can contain "conversion specifiers", consisting of the '%' character followed by another character. These specifiers are expanded in the resulting prompt as follows: Sequence Expansion ------------------------------------------------------------------- %f name of the current database file %p program invocation name %P package name ('GDBM') %v program version %_ single space character %% % The default value is '%p>%_', i.e. the program name, followed by a "greater than" sign, followed by a single space. -- gdbmtool variable: string ps2 Secondary prompt. See 'ps1' for a description of its value. This prompt is displayed before reading the second and subsequent lines of a multi-line command. The default value is '%_>%_'. -- gdbmtool variable: string delim1 A string used to delimit fields of a structured datum on output (*note definitions::). Default is ',' (a comma). This variable cannot be unset. -- gdbmtool variable: string delim2 A string used to delimit array items when printing a structured datum (*note definitions::). Default is ',' (a comma). This variable cannot be unset. -- gdbmtool variable: string pager The name and command line of the pager program to pipe output to. This program is used in interactive mode when the estimated number of output lines is greater then the number of lines on your screen. The default value is inherited from the environment variable 'PAGER'. Unsetting this variable disables paging. -- gdbmtool variable: bool quiet Whether to display a welcome banner at startup. This variable should be set in a startup script file (*note startup files::). *Note -q option::. The following variables control how the database is opened: -- gdbmtool variable: numeric blocksize Sets the block size. *Note block_size: Open. Unset by default. -- gdbmtool variable: numeric cachesize Sets the cache size. *Note GDBM_SETCACHESIZE: Options. By default this variable is not set. -- gdbmtool variable: string open Open mode. The following values are allowed: newdb Truncate the database if it exists or create a new one. Open it in read-write mode. Technically, this sets the 'GDBM_NEWDB' flag in call to 'gdbm_open'. *Note GDBM_NEWDB: Open. wrcreat rw Open the database in read-write mode. Create it if it does not exist. This is the default. Technically speaking, it sets the 'GDBM_WRCREAT' flag in call to 'gdbm_open'. *Note GDBM_WRCREAT: Open. reader readonly Open the database in read-only mode. Signal an error if it does not exist. This sets the 'GDBM_READER' flag (*note GDBM_READER: Open.). Attempting to set any other value or to unset this variable produces an error. -- gdbmtool variable: number filemode File mode (in octal) for creating new database files and database dumps. -- gdbmtool variable: bool lock Lock the database. This is the default. Setting this variable to false or unsetting it results in passing 'GDBM_NOLOCK' flag to 'gdbm_open' (*note GDBM_NOLOCK: Open.). -- gdbmtool variable: bool mmap Use memory mapping. This is the default. Setting this variable to false or unsetting it results in passing 'GDBM_NOMMAP' flag to 'gdbm_open' (*note GDBM_NOMMAP: Open.). -- gdbmtool variable: bool sync Flush all database writes on disk immediately. Default is false. *Note GDBM_SYNC: Open. The following commands are used to list or modify the variables: -- command verb: set [ASSIGNMENTS] When used without arguments, lists all variables and their values. Unset variables are shown after a comment sign ('#'). For string and numeric variables, values are shown after an equals sign. For boolean variables, only the variable name is displayed if the variable is 'true'. If it is 'false', its name is prefixed with 'no'. For example: ps1="%p>%_" ps2="%_>%_" delim1="," delim2="," confirm # cachesize is unset # blocksize is unset open="wrcreat" lock mmap nosync pager="less" # quiet is unset If used with arguments, the 'set' command alters the specified variables. In this case, arguments are variable assignments in the form 'NAME=VALUE'. For boolean variables, the VALUE is interpreted as follows: if it is numeric, '0' stands for 'false', any non-zero value stands for 'true'. Otherwise, the values 'on', 'true', and 'yes' denote 'true', and 'off', 'false', 'no' stand for 'false'. Alternatively, only the name of a boolean variable can be supplied to set it to 'true', and its name prefixed with 'no' can be used to set it to false. For example, the following command sets the 'delim2' variable to ';' and the 'confirm' variable to 'false': set delim2=";" noconfirm -- command verb: unset VARIABLES Unsets the listed variables. The effect of unsetting depends on the variable. Unless explicitly described in the discussion of the variables above, unsetting a boolean variable is equivalent to setting it to 'false'. Unsetting a string variable is equivalent to assigning it an empty string.  File: gdbm.info, Node: commands, Next: definitions, Prev: variables, Up: shell 21.2.2 Gdbmtool Commands ------------------------ -- command verb: avail Print the "avail list". -- command verb: bucket NUM Print the bucket number NUM and set it as the current one. -- command verb: cache Print the bucket cache. -- command verb: close Close the currently open database. -- command verb: count Print the number of entries in the database. -- command verb: current Print the current bucket. -- command verb: delete KEY Delete record with the given KEY -- command verb: dir Print hash directory. -- command verb: export FILE-NAME [truncate] [binary|ascii] Export the database to the flat file FILE-NAME. *Note Flat files::, for a description of the flat file format and its purposes. This command will not overwrite an existing file, unless the 'truncate' parameter is also given. Another optional argument determines the type of the dump (*note Flat files::). By default, ASCII dump is created. The global variable 'filemode' specifies the permissions to use for the created output file. See also *note gdbmexport::. -- command verb: fetch KEY Fetch and display the record with the given KEY. -- command verb: first Fetch and display the first record in the database. Subsequent records can be fetched using the 'next' command (see below). *Note Sequential::, for more information on sequential access. -- command verb: hash KEY Compute and display the hash value for the given KEY. -- command verb: header Print file header. -- command verb: help -- command verb: ? Print a concise command summary, showing each command verb with its parameters and a short description of what it does. Optional arguments are enclosed in square brackets. -- command verb: import FILE-NAME [replace] [nometa] Import data from a flat dump file FILE-NAME (*note Flat files::). If the word 'replace' is given as an argument, any records with the same keys as the already existing ones will replace them. The word 'nometa' turns off restoring meta-information from the dump file. -- command verb: history -- command verb: history COUNT -- command verb: history N COUNT Shows the command history list with line numbers. When used without arguments, shows entire history. When used with one argument, displays COUNT last commands from the history. With two arguments, displays COUNT commands starting from Nth command. Command numbering starts with 1. This command is available only if GDBM was compiled with GNU Readline. The history is saved in file '.gdbmtool_history' in the user's home directory. If this file exists upon startup, it is read to populate the history. Thus, command history is preserved between 'gdbmtool' invocations. -- command verb: list List the contents of the database. -- command verb: next [KEY] Sequential access: fetch and display the next record. If the KEY is given, the record following the one with this key will be fetched. Issuing several 'next' commands in row is rather common. A shortcut is provided to facilitate such use: if the last entered command was 'next', hitting the 'Enter' key repeats it without arguments. See also 'first', above. *Note Sequential::, for more information on sequential access. -- command verb: open FILENAME Open the database file FILENAME. If successful, any previously open database is closed. Otherwise, if the operation fails, the currently opened database remains unchanged. This command takes additional information from the following variables: 'open' The database access mode. *Note The OPEN variable: openvar, for a list of its values. 'lock' Whether or not to lock the database. Default is 'on'. 'mmap' Use the memory mapping. Default is 'on'. 'sync' Synchronize after each write. Default is 'off'. 'filemode' Specifies the permissions to use in case a new file is created. *Note open parameters::, for a detailed description of these variables. -- command verb: quit Close the database and quit the utility. -- command verb: reorganize Reorganize the database (*note Reorganization::). -- command verb: source FILENAME Read 'gdbmtool' commands from the file FILENAME. -- command verb: status Print current program status. The following example shows the information displayed: Database file: junk.gdbm Database is open define key string define content string The two 'define' strings show the defined formats for key and content data. *Note definitions::, for a detailed discussion of their meaning. -- command verb: store KEY DATA Store the DATA with KEY in the database. If KEY already exists, its data will be replaced. -- command verb: version Print the version of 'gdbm'.  File: gdbm.info, Node: definitions, Next: startup files, Prev: commands, Up: shell 21.2.3 Data Definitions ----------------------- GDBM databases are able to keep data of any type, both in the key and in the content part of a record. Quite often these data are structured, i.e. they consist of several fields of various types. 'Gdbmtool' provides a mechanism for handling such kind of records. The 'define' command defines a record structure. The general syntax is: define WHAT DEFINITION where WHAT is 'key' to defining the structure of key data and 'content' to define the structure of the content records. The DEFINITION can be of two distinct formats. In the simplest case it is a single data type. For example, define content int defines content records consisting of a single integer field. Supported data types are: char Single byte (signed). short Signed short integer. ushort Unsigned short integer. int Signed integer. unsigned uint Unsigned integer. long Signed long integer. ulong Unsigned long integer. llong Signed long long integer. ullong Unsigned long long integer. float A floating point number. double Double-precision floating point number. string Array of bytes. stringz Null-terminated string, trailing null being part of the string. All numeric data types (integer as well as floating point) have the same respective widths as in C language on the host where the database file resides. The 'string' and 'stringz' are special. Both define a string of bytes, similar to 'char x[]' in C. The former defines an array of bytes, the latter - a null-terminated string. This makes a difference, in particular, when the string is the only part of datum. Consider the following two definitions: 1. 'define key string' 2. 'define key stringz' Now, suppose we want to store the string "ab" in the key. Using the definition (1), the 'dptr' member of GDBM 'datum' will contain two bytes: 'a', and 'b'. Consequently, the 'dsize' member will have the value 2. Using the definition (2), the 'dptr' member will contain three bytes: 'a', 'b', and ASCII 0. The 'dsize' member will have the value 3. The definition (1) is the default for both key and content. The second form of the 'define' statement is similar to the C 'struct' statement and allows for defining structural data. In this form, the DEFINITION part is a comma-separated list of data types and variables enclosed in curly braces. In contrast to the rest of 'gdbm' commands, this command is inherently multiline and is terminated with the closing curly brace. For example: define content { int status, pad 8, char id[3], string name } This defines a structure consisting of three members: an integer 'status', an array of 8 bytes 'id', and a null-terminated string 'name'. Notice the 'pad' statement: it allows to introduce padding between structure members. Another useful statement is 'offset': it specifies that the member following it begins at the given offset in the structure. Assuming the size of 'int' is 8 bytes, the above definition can also be written as define content { int status, offset 16, char id[3], string name } _NOTE_: The 'string' type can reasonably be used only if it is the last or the only member of the data structure. That's because it provides no information about the number of elements in the array, so it is interpreted to contain all bytes up to the end of the datum. When displaying the structured data, 'gdbmtool' precedes each value with the corresponding field name and delimits parts of the structure with the string defined in the 'delim1' variable (*note variables::). Array elements are delimited using the string from 'delim2'. For example: gdbmtool> fetch foo status=2,id={ a, u, x },name="quux" To supply a structured datum as an argument to a 'gdbmtool' command, use the same notation, but without field names, e.g.: gdbmtool> hash { 2, {a,u,x}, "quux" } hash value = 13089969.  File: gdbm.info, Node: startup files, Prev: definitions, Up: shell 21.2.4 Startup Files -------------------- Upon startup 'gdbmtool' looks for a file named '.gdbmtoolrc' first in the current working directory and, if not found, in the home directory of the user who started the command. If found, this file is read and interpreted as a list of 'gdbmtool' commands. This allows you to customize the program behavior. Following is an example startup file which disables the welcome banner, sets command line prompt to contain the name of the database file in parentheses and defines the structure of the database content records: set quiet set ps1="(%f) " define key stringz define content { int time, pad 4, int status }  File: gdbm.info, Node: gdbm_dump, Next: gdbm_load, Prev: gdbmtool, Up: Top 22 The 'gdbm_dump' utility ************************** The 'gdbm_dump' utility creates a flat file dump of a GDBM database (*note Flat files::). It takes one mandatory argument: the name of the source database file. The second argument, if given, specifies the name of the output file. If not given, 'gdbm_dump' will produce the dump on the standard output. For example, the following invocation creates a dump of the database 'file.db' in the file 'file.dump': $ gdbm_dump file.db file.dump By default the utility creates dumps in ASCII format (*note ASCII: Flat files.). Another format can be requested using the '--format' ('-H') option. The 'gdbm_dump' utility understands the following command line options: '-H FMT' '--format=FMT' Select output format. Valid values for FMT are: 'binary' or '0' to select binary dump format, and 'ascii' or '1' to select ASCII format. '-h' '--help' Print a concise help summary. '-V' '--version' Print program version and licensing information and exit. '--usage' Print a terse invocation syntax summary along with a list of available command line options.  File: gdbm.info, Node: gdbm_load, Next: gdbmexport, Prev: gdbm_dump, Up: Top 23 The 'gdbm_load' utility ************************** The 'gdbm_load' utility restores a GDBM database from a flat file. The utility requires at least one argument: the name of the input flat file. If it is '-', the standard input will be read. The format of the input file is detected automatically. By default the utility attempts to restore the database under its original name, as stored in the input file. It will fail to do so if the input is in binary format. In that case, the name of the database must be given as the second argument. In general, if two arguments are given the second one is treated as the name of the database to create, overriding the file name specified in the flat file. The utility understands the following command line arguments: '-b NUM' '--block-size=NUM' Sets block size. *Note block_size: Open. '-c NUM' '--cache-size=NUM' Sets cache size. *Note GDBM_SETCACHESIZE: Options. '-M' '--mmap' Use memory mapping. '-m MODE' '--mode=MODE' Sets the file mode. The argument is the desired file mode in octal. '-n' '--no-meta' Do not restore file meta-data (ownership and mode) from the flat file. '-r' '--replace' Replace existing keys. '-u USER[:GROUP]' '--user=USER[:GROUP]' Set file owner. The USER can be either a valid user name or UID. Similarly, the GROUP is either a valid group name or GID. If GROUP is not given, the main group of USER is used. User and group parts can be separated by a dot, instead of the colon. '-h' '--help' Print a concise help summary. '-V' '--version' Print program version and licensing information and exit. '--usage' Print a terse invocation syntax summary along with a list of available command line options.  File: gdbm.info, Node: gdbmexport, Next: Exit codes, Prev: gdbm_load, Up: Top 24 Export a database into a portable format. ******************************************** The 'gdbmexport' utility converts the database of an older GDBM version into a binary flat format. The utility takes two mandatory arguments: the name of the database file to convert and the output file name, e.g.: $ gdbmexport junk.gdbm junk.flat In addition the following two options are understood: '-h' Display short usage summary and exit. '-v' Display program version and licensing information, and exit.  File: gdbm.info, Node: Exit codes, Next: Bugs, Prev: gdbmexport, Up: Top 25 Exit codes ************* All GDBM utilities return uniform exit codes. These are summarized in the table below: Code Meaning -------------------------------------------------------------------------- 0 Successful termination. 1 A fatal error occurred. 2 Program was unable to restore file ownership or mode. 3 Command line usage error.  File: gdbm.info, Node: Bugs, Next: Resources, Prev: Exit codes, Up: Top 26 Problems and bugs. ********************* If you have problems with GNU 'dbm' or think you've found a bug, please report it. Before reporting a bug, make sure you've actually found a real bug. Carefully reread the documentation and see if it really says you can do what you're trying to do. If it's not clear whether you should be able to do something or not, report that too; it's a bug in the documentation! Before reporting a bug or trying to fix it yourself, try to isolate it to the smallest possible input file that reproduces the problem. Then send us the input file and the exact results 'gdbm' gave you. Also say what you expected to occur; this will help us decide whether the problem was really in the documentation. Once you've got a precise problem, send e-mail to . Please include the version number of GNU 'dbm' you are using. You can get this information by printing the variable 'gdbm_version' (*note Variables::). Non-bug suggestions are always welcome as well. If you have questions about things that are unclear in the documentation or are just obscure features, please report them too. You may contact the authors and maintainers by e-mail: , ,  File: gdbm.info, Node: Resources, Next: GNU Free Documentation License, Prev: Bugs, Up: Top 27 Additional resources *********************** For the latest updates and pointers to additional resources, visit . In particular, a copy of 'gdbm' documentation in various formats is available online at . Latest versions of 'gdbm' can be downloaded from anonymous FTP: , or via HTTP from , or from any GNU mirror worldwide. See , for a list of mirrors. To track 'gdbm' development, visit .  File: gdbm.info, Node: GNU Free Documentation License, Next: Index, Prev: Resources, Up: Top Appendix A GNU Free Documentation License ***************************************** Version 1.3, 3 November 2008 Copyright (C) 2000-2002, 2007-2008, 2011, 2017-2018 Free Software Foundation, Inc. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. 0. PREAMBLE The purpose of this License is to make a manual, textbook, or other functional and useful document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. 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ADDENDUM: How to use this License for your documents ==================================================== To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page: Copyright (C) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''. If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the "with...Texts." line with this: with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.  File: gdbm.info, Node: Index, Prev: GNU Free Documentation License, Up: Top Index ***** [index] * Menu: * (*errfun) on gdbm_recovery: Recovery. (line 52) * --newdb, gdbmtool option: gdbmtool. (line 20) * --read-only, gdbmtool option: gdbmtool. (line 16) * -n, gdbmtool option: gdbmtool. (line 20) * -r, gdbmtool option: gdbmtool. (line 16) * .gdbmtoolrc: startup files. (line 6) * ?: commands. (line 58) * _GDBM_MAX_ERRNO: Variables. (line 31) * _GDBM_MIN_ERRNO: Variables. (line 28) * avail: commands. (line 6) * backup_name of gdbm_recovery: Recovery. (line 95) * blocksize: variables. (line 66) * bucket: commands. (line 9) * cache: commands. (line 12) * cachesize: variables. (line 69) * close: commands. (line 15) * close-on-exec: Open. (line 57) * closing database: Close. (line 6) * command line options, gdbmtool: invocation. (line 6) * compatibility layer: Compatibility. (line 6) * confirm: variables. (line 8) * count: commands. (line 18) * creating a database, gdbmtool: gdbmtool. (line 20) * current: commands. (line 21) * data of gdbm_recovery: Recovery. (line 58) * database options: Options. (line 6) * database reorganization: Reorganization. (line 6) * database synchronization: Sync. (line 6) * database, closing: Close. (line 6) * database, opening or creating: Open. (line 6) * DBM functions: dbm. (line 6) * dbm.h: Compatibility. (line 10) * dbmclose: dbm. (line 22) * dbminit: dbm. (line 10) * dbm_clearerr: ndbm. (line 97) * dbm_close: ndbm. (line 25) * dbm_delete: ndbm. (line 56) * dbm_dirfno: ndbm. (line 100) * dbm_error: ndbm. (line 92) * dbm_fetch: ndbm. (line 29) * dbm_firstkey: ndbm. (line 61) * DBM_INSERT: ndbm. (line 49) * dbm_nextkey: ndbm. (line 71) * dbm_open: ndbm. (line 8) * dbm_pagfno: ndbm. (line 108) * dbm_rdonly: ndbm. (line 112) * DBM_REPLACE: ndbm. (line 46) * dbm_store: ndbm. (line 38) * default database, gdbmtool: gdbmtool. (line 9) * delete: dbm. (line 41) * delete <1>: commands. (line 24) * deleting records: Delete. (line 6) * deletion in iteration loops: Sequential. (line 60) * delim1: variables. (line 39) * delim2: variables. (line 45) * dir: commands. (line 27) * dir file: Compatibility. (line 21) * error code, most recent: Errors. (line 21) * error codes: Error codes. (line 6) * error strings: Errors. (line 6) * exit code: Exit codes. (line 6) * export: Flat files. (line 6) * export <1>: commands. (line 30) * failed_buckets of gdbm_recovery: Recovery. (line 92) * failed_keys of gdbm_recovery: Recovery. (line 89) * fetch: dbm. (line 25) * fetch <1>: commands. (line 43) * fetching records: Fetch. (line 6) * filemode: variables. (line 99) * first: commands. (line 46) * firstkey: dbm. (line 47) * Flat file format: Flat files. (line 6) * gdbmexport: gdbmexport. (line 6) * gdbmtool: gdbmtool. (line 6) * GDBM_BACKUP_FAILED: Error codes. (line 165) * GDBM_BAD_FILE_OFFSET: Error codes. (line 114) * GDBM_BAD_MAGIC_NUMBER: Error codes. (line 49) * GDBM_BAD_OPEN_FLAGS: Error codes. (line 118) * GDBM_BLOCK_SIZE_ERROR: Error codes. (line 15) * GDBM_BSEXACT: Open. (line 52) * GDBM_BSEXACT <1>: Error codes. (line 15) * GDBM_BYTE_SWAPPED: Error codes. (line 110) * GDBM_CACHESIZE: Options. (line 27) * GDBM_CANNOT_REPLACE: Error codes. (line 90) * GDBM_CANT_BE_READER: Error codes. (line 57) * GDBM_CANT_BE_WRITER: Error codes. (line 62) * GDBM_CENTFREE: Options. (line 74) * gdbm_check_syserr: Errors. (line 41) * gdbm_clear_error: Errors. (line 56) * GDBM_CLOEXEC: Open. (line 57) * gdbm_close: Close. (line 9) * GDBM_COALESCEBLKS: Options. (line 88) * gdbm_copy_meta: Open. (line 89) * gdbm_count: Count. (line 6) * gdbm_db_strerror: Errors. (line 48) * gdbm_delete: Delete. (line 8) * gdbm_delete and sequential access: Sequential. (line 60) * GDBM_DIR_OVERFLOW: Error codes. (line 168) * gdbm_dump: gdbm_dump. (line 6) * gdbm_dump <1>: Flat files. (line 46) * gdbm_dump_to_file: Flat files. (line 147) * GDBM_EMPTY_DATABASE: Error codes. (line 53) * gdbm_errlist[]: Variables. (line 16) * gdbm_errno: Variables. (line 8) * gdbm_errno <1>: Errors. (line 6) * GDBM_ERR_FILE_MODE: Flat files. (line 135) * GDBM_ERR_FILE_MODE <1>: Error codes. (line 153) * GDBM_ERR_FILE_OWNER: Flat files. (line 132) * GDBM_ERR_FILE_OWNER <1>: Error codes. (line 146) * gdbm_exists: Fetch. (line 39) * gdbm_export: Flat files. (line 170) * gdbm_export_to_file: Flat files. (line 179) * GDBM_FASTMODE: Options. (line 48) * gdbm_fdesc: Locking. (line 13) * gdbm_fd_open: Open. (line 79) * gdbm_fetch: Fetch. (line 6) * GDBM_FILE_EOF: Error codes. (line 129) * GDBM_FILE_OPEN_ERROR: Error codes. (line 20) * GDBM_FILE_READ_ERROR: Error codes. (line 42) * GDBM_FILE_SEEK_ERROR: Error codes. (line 35) * GDBM_FILE_STAT_ERROR: Error codes. (line 122) * GDBM_FILE_WRITE_ERROR: Error codes. (line 28) * gdbm_firstkey: Sequential. (line 13) * GDBM_GETBLOCKSIZE: Options. (line 143) * GDBM_GETCACHESIZE: Options. (line 37) * GDBM_GETCOALESCEBLKS: Options. (line 100) * GDBM_GETDBNAME: Options. (line 123) * GDBM_GETFLAGS: Options. (line 41) * GDBM_GETMAXMAPSIZE: Options. (line 110) * GDBM_GETMMAP: Options. (line 119) * GDBM_GETSYNCMODE: Options. (line 70) * GDBM_ILLEGAL_DATA: Error codes. (line 96) * gdbm_import: Flat files. (line 183) * gdbm_import_from_file: Flat files. (line 196) * GDBM_INSERT: Store. (line 20) * GDBM_ITEM_NOT_FOUND: Error codes. (line 81) * gdbm_last_errno: Errors. (line 21) * gdbm_last_syserr: Errors. (line 25) * gdbm_load: gdbm_load. (line 6) * gdbm_load <1>: Flat files. (line 75) * gdbm_load_from_file: Flat files. (line 163) * GDBM_MALLOC_ERROR: Error codes. (line 12) * gdbm_needs_recovery: Errors. (line 68) * GDBM_NEED_RECOVERY: Error codes. (line 160) * GDBM_NEWDB: Open. (line 32) * gdbm_nextkey: Sequential. (line 25) * GDBM_NOLOCK: Open. (line 44) * GDBM_NOLOCK <1>: Locking. (line 6) * GDBM_NOMMAP: Open. (line 44) * GDBM_NO_DBNAME: Error codes. (line 140) * GDBM_NO_ERROR: Error codes. (line 9) * gdbm_open: Open. (line 6) * GDBM_OPT_ALREADY_SET: Error codes. (line 100) * GDBM_OPT_ILLEGAL: Error codes. (line 105) * GDBM_RCVR_BACKUP: Recovery. (line 96) * GDBM_RCVR_ERRFUN: Recovery. (line 54) * GDBM_RCVR_FORCE: Recovery. (line 102) * GDBM_RCVR_MAX_FAILED_BUCKETS: Recovery. (line 68) * GDBM_RCVR_MAX_FAILED_KEYS: Recovery. (line 62) * GDBM_RCVR_MAX_FAILURES: Recovery. (line 75) * GDBM_READER: Open. (line 32) * GDBM_READER_CANT_DELETE: Error codes. (line 66) * GDBM_READER_CANT_REORGANIZE: Error codes. (line 76) * GDBM_READER_CANT_STORE: Error codes. (line 71) * gdbm_recover: Recovery. (line 16) * gdbm_reorganize: Reorganization. (line 8) * GDBM_REORGANIZE_FAILED: Error codes. (line 86) * GDBM_REPLACE: Store. (line 20) * GDBM_SETCACHESIZE: Options. (line 27) * GDBM_SETCENTFREE: Options. (line 74) * GDBM_SETCOALESCEBLKS: Options. (line 88) * GDBM_SETMAXMAPSIZE: Options. (line 104) * GDBM_SETMMAP: Options. (line 114) * gdbm_setopt: Options. (line 9) * GDBM_SETSYNCMODE: Options. (line 57) * gdbm_store: Store. (line 6) * gdbm_strerror: Errors. (line 12) * GDBM_SYNC: Open. (line 44) * GDBM_SYNC <1>: Sync. (line 6) * gdbm_sync: Sync. (line 14) * GDBM_SYNCMODE: Options. (line 57) * gdbm_syserr[]: Variables. (line 23) * gdbm_version: Variables. (line 34) * gdbm_version_cmp: Variables. (line 63) * GDBM_VERSION_MAJOR: Variables. (line 49) * GDBM_VERSION_MINOR: Variables. (line 52) * gdbm_version_number[3]: Variables. (line 37) * GDBM_VERSION_PATCH: Variables. (line 55) * GDBM_WRCREAT: Open. (line 32) * GDBM_WRITER: Open. (line 32) * global error state: Errors. (line 6) * GNU Readline: shell. (line 64) * hash: commands. (line 51) * header: commands. (line 54) * help: commands. (line 57) * history: commands. (line 69) * history <1>: commands. (line 70) * history <2>: commands. (line 71) * import: Flat files. (line 6) * import <1>: commands. (line 63) * init file, gdbmtool: startup files. (line 6) * interactive mode, gdbmtool: shell. (line 6) * iterating over records: Sequential. (line 6) * iteration and gdbm_delete: Sequential. (line 60) * iteration loop: Sequential. (line 40) * iteration loop, using NDBM: ndbm. (line 79) * junk.gdbm: gdbmtool. (line 9) * libgdbm_compat: Compatibility. (line 10) * list: commands. (line 84) * lock: variables. (line 103) * locking: Locking. (line 6) * looking up records: Fetch. (line 6) * max_failed_buckets of gdbm_recovery: Recovery. (line 67) * max_failed_keys of gdbm_recovery: Recovery. (line 61) * max_failures of gdbm_recovery: Recovery. (line 74) * mmap: variables. (line 109) * most recent error code: Errors. (line 21) * NDBM functions: ndbm. (line 6) * ndbm.h: Compatibility. (line 10) * next: commands. (line 87) * nextkey: dbm. (line 57) * number of records: Count. (line 6) * open: variables. (line 73) * open <1>: commands. (line 101) * opening the database: Open. (line 6) * options, database: Options. (line 6) * pag file: Compatibility. (line 21) * pager: variables. (line 51) * ps1: variables. (line 14) * ps2: variables. (line 32) * quiet: variables. (line 59) * quit: commands. (line 125) * read-only mode, gdbmtool: gdbmtool. (line 16) * readline: shell. (line 64) * record, deleting: Delete. (line 6) * record, fetching: Fetch. (line 6) * records, iterating over: Sequential. (line 6) * records, storing: Store. (line 6) * records, testing existence: Fetch. (line 37) * recovered_buckets of gdbm_recovery: Recovery. (line 86) * recovered_keys of gdbm_recovery: Recovery. (line 83) * reorganization, database: Reorganization. (line 6) * reorganize: commands. (line 128) * sequential access: Sequential. (line 6) * sequential access, using NDBM: ndbm. (line 79) * set: variables. (line 121) * source: commands. (line 131) * startup file, gdbmtool: startup files. (line 6) * status: commands. (line 134) * store: dbm. (line 34) * store <1>: commands. (line 147) * storing records: Store. (line 6) * sync: variables. (line 115) * synchronization, database: Sync. (line 6) * unset: variables. (line 158) * variables, gdbmtool: variables. (line 6) * version: commands. (line 151) * version number: Variables. (line 34)  Tag Table: Node: Top900 Node: Copying3100 Node: Intro4883 Node: List6304 Node: Open7599 Node: Close12118 Node: Count12573 Node: Store12979 Node: Fetch14960 Node: Delete16635 Node: Sequential17402 Node: Reorganization20720 Node: Sync21730 Node: Flat files22820 Ref: gdbm_load function26344 Node: Errors31792 Ref: gdbm_check_syserr33262 Node: Recovery34901 Node: Options39515 Node: Locking45336 Node: Variables45930 Node: Error codes48583 Node: Compatibility54847 Node: ndbm56410 Node: dbm61251 Node: gdbmtool63911 Node: invocation64880 Ref: -q option65492 Node: shell65982 Ref: backslash-interpretation67192 Node: variables68941 Ref: quiet71168 Ref: open parameters71364 Ref: openvar71686 Ref: filemode72549 Node: commands75121 Ref: gdbmtool export75776 Ref: gdbmtool import77032 Node: definitions80322 Node: startup files84514 Node: gdbm_dump85316 Node: gdbm_load86557 Node: gdbmexport88434 Node: Exit codes89048 Node: Bugs89596 Node: Resources90948 Node: GNU Free Documentation License91667 Node: Index116823  End Tag Table