lineno

Display specific lines or ranges of lines of a file

Motivation

Suppose you need lines 10 to 15 of file 'file.txt' as part of a greater pipeline. You can use head and tail together in with head -n 15 file.txt | tail -n 6.

While that's relatively easy, lineno makes it even easier:

$ lineno -f file.txt 10..15
foo
bar
baz
qux
quux
didgeridoo

What if we want lines 10 through 15 and line 26?. My unix-foo isn't good enough to do that in a single pipeline off the top of my head. But of course its trivial with lineno:

$ lineno -f file.txt 10..15 26
foo
bar
baz
qux
quux
didgeridoo
supercalifragilisticexpialidocious

(My contrived-example-foo has always outpaced my unix-foo)

Detailed Usage

Filters

lineno takes an arbitrary number of filters and returns lines matching those filters.

Filters any combo of

• Standalone line numbers, e.g. 10

$ lineno -f ./tests/foo.txt 2
bar

• Ranges, e.g.1:10

$ lineno -f ./tests/foo.txt 1:3
foo
bar
baz

• Both the upper and lower bounds on ranges are inclusive

• Ranges may either be specified with a ':' or '..' (1..10 and 1:10 are equivalent) (like the head util)

• Omitting the upperbound returns all lines from the lowerbound to the end of the file (24..) (like the tail util)

$ lineno -f ./tests/rocket.txt 8..
3
2
1
blast off!

• Likewise, omitting the lowerbound returns all lines from the start of the file to the upperbound

$ lineno -f ./tests/rocket.txt ..4
10
9
8
7

• Multiple filters may be specified by commas or whitespace

  • There is no need for lists of filters to be in numerical order

$ lineno -f file.txt 3 2 1 10:12
long
text
innoculous
foo
bar
baz

• Or unique

$ lineno -f file.txt 23 23 23 25
spam
spam
spam
eggs

Running lineno without any filters cats the file (outputs the file unmodified)

$ lineno -f ./tests/small.txt
line 1
line 2
line 3

which, btw, is the same as an empty range (idk why one would want to do that instead of using cat, but it's possible)

$ lineno -f ./tests/small.txt ..
line 1
line 2
line 3

If no file is specified, lineno will read from stdin

$ cat ./tests/small.txt | lineno 3
line 3

Oh hey, that last example is a useless use of cat. Lets make it even more useless for fun

$ lineno -f ./tests/small.txt .. | lineno 3
line 3

Options

• -f, --file <file> You've already seen the '-f' option to provide an input file:

$ lineno -f ./tests/small.txt
line 1
line 2
line 3

• -n,--number The '-n' option displays line numbers along with the line's content:

$ lineno -f ./tests/small.txt -n
1: line 1
2: line 2
3: line 3