#### **`systeroid`** — A more powerful alternative to sysctl(8). [`sysctl(8)`](https://man7.org/linux/man-pages/man8/sysctl.8.html) is a utility on Unix-like operating systems that is used to read and modify the attributes of the kernel such as its version number, maximum limits, and security settings[\*](https://en.wikipedia.org/wiki/Sysctl). **systeroid** is "_sysctl on steroids_". It can do everything that sysctl does and even more. It provides a safer, more performant, and user-friendly CLI/TUI for managing the kernel parameters at runtime.



**systeroid** is implemented using [procfs](https://en.wikipedia.org/wiki/Procfs) which is the virtual file system that is typically mapped to a mount point named `/proc` at boot time. This means checking the value of some kernel parameter requires opening a file in this virtual filesystem, reading its contents, parsing them, and closing the file. In [Linux](https://en.wikipedia.org/wiki/Linux), these dynamically configurable kernel options are available under `/proc/sys` which contains directories representing the sections of the kernel and readable/writable virtual files. For example, to enable/disable IP forwarding, `1` or `0` could be written in `/proc/sys/net/ipv4/ip_forward` or `systeroid ip_forward=1` command can be used to change the value of the parameter. Although **systeroid** does not need the parameter section to be specified explicitly, it is important to know the sections and their areas of impact. Here are the available kernel sections according to the [Linux kernel documentation](https://www.kernel.org/doc/html/latest/admin-guide/sysctl/index.html): | Section | Path | Description | | ---------- | ------------------- | ------------------------------------------------------------- | | **abi** | `/proc/sys/abi/` | execution domains & personalities | | **fs** | `/proc/sys/fs/` | filesystem settings | | **kernel** | `/proc/sys/kernel/` | global kernel information / miscellaneous settings | | **net** | `/proc/sys/net/` | networking settings | | **sunrpc** | `/proc/sys/sunrpc/` | SUN Remote Procedure Call settings | | **user** | `/proc/sys/user/` | user namespace limits | | **vm** | `/proc/sys/vm/` | memory management tuning buffer and cache management settings | | **dev** | `/proc/sys/dev/` | device specific information | | **debug** | `/proc/sys/debug/` | - | --- - [Requirements](#requirements) - [Installation](#installation) - [Cargo](#cargo) - [Arch Linux](#arch-linux) - [Alpine Linux](#alpine-linux) - [Binary releases](#binary-releases) - [Building from source](#building-from-source) - [Docker](#docker) - [Images](#images) - [Usage](#usage) - [Building](#building) - [Usage](#usage-1) - [Options](#options) - [Examples](#examples) - [Listing parameters](#listing-parameters) - [Filtering by section](#filtering-by-section) - [Displaying values](#displaying-values) - [Setting values](#setting-values) - [Loading values from a file](#loading-values-from-a-file) - [Loading values from the system directories](#loading-values-from-the-system-directories) - [Searching parameters](#searching-parameters) - [Showing information about parameters](#showing-information-about-parameters) - [Verbose logging](#verbose-logging) - [TUI](#tui) - [Usage](#usage-2) - [Key Bindings](#key-bindings) - [Examples](#examples-1) - [Launching](#launching) - [Showing help](#showing-help) - [Scrolling](#scrolling) - [Toggling the kernel section](#toggling-the-kernel-section) - [Searching](#searching) - [Setting values](#setting-values-1) - [Saving values](#saving-values) - [Running commands](#running-commands) - [Copying to clipboard](#copying-to-clipboard) - [Changing the colors](#changing-the-colors) - [Viewing the parameter documentation](#viewing-the-parameter-documentation) - [Setting the refresh rate](#setting-the-refresh-rate) - [Logging](#logging) - [Configuration](#configuration) - [Resources](#resources) - [References](#references) - [Logo](#logo) - [Social Links](#social-links) - [In The Media](#in-the-media) - [Funding](#funding) - [Contributing](#contributing) - [License](#license) - [Copyright](#copyright) ## Requirements - [`Rust`](https://www.rust-lang.org/) (`>=1.64.0`) (see [building from source](#building-from-source)) - [`libxcb`](https://gitlab.freedesktop.org/xorg/lib/libxcb) (for [clipboard support](#copying-to-clipboard)) - [`linux-documentation`](https://www.kernel.org/doc/) (for [viewing the documentation](#viewing-the-parameter-documentation)) To install the runtime dependencies: - on Arch Linux: `pacman -S libxcb libxkbcommon linux-docs` - on Debian/Ubuntu: `apt-get install libx11-dev libxcb-shape0-dev libxcb-xfixes0-dev libxkbcommon-dev linux-doc` - on Fedora: `dnf install libX11-devel kernel-doc` ## Installation

Packaging status

[](https://repology.org/project/systeroid/versions)

### Cargo **systeroid** is available on [crates.io](https://crates.io/crates/systeroid): ```sh cargo install systeroid cargo install systeroid-tui ``` ### Arch Linux **systeroid** can be installed from the [community repository](https://archlinux.org/packages/community/x86_64/systeroid/) using [pacman](https://wiki.archlinux.org/title/Pacman): ```sh pacman -S systeroid ``` ### Alpine Linux **systeroid** is available for [Alpine Edge](https://pkgs.alpinelinux.org/packages?name=systeroid&branch=edge). It can be installed via [apk](https://wiki.alpinelinux.org/wiki/Alpine_Package_Keeper) after enabling the [community repository](https://wiki.alpinelinux.org/wiki/Repositories). ```sh apk add systeroid ``` ### Binary releases See available [releases](https://github.com/orhun/systeroid/releases) that are automated by [Continuous Deployment](.github/workflows/cd.yml) workflow. ### Building from source ```sh # clone the repository git clone https://github.com/orhun/systeroid && cd systeroid/ # binaries will be located at: # - target/release/systeroid # - target/release/systeroid-tui CARGO_TARGET_DIR=target cargo build --release ``` Also see [requirements](#requirements). ### Docker #### Images Docker builds are [automated](./.github/workflows/docker.yml) and images are available in the following registries: - [Docker Hub](https://hub.docker.com/r/orhunp/systeroid) - [GitHub Container Registry](https://github.com/orhun/systeroid/pkgs/container/systeroid) #### Usage The following command can be used to interactively view the documentation of selected parameters: ```sh docker run --rm -it "orhunp/systeroid:${TAG:-latest}" --tui ``` Docker containers share the host system's kernel and its settings thus access to `/proc` and `/sys` are restricted for security. That is why it is not possible (and not recommended) to tweak the kernel parameters within a container. [\*](https://stackoverflow.com/questions/54845095/cannot-run-sysctl-command-in-dockerfile) #### Building Custom Docker images can be built from the [Dockerfile](./Dockerfile): ```sh docker build -t systeroid . ``` ## Usage ``` systeroid [options] [variable[=value] ...] --load[=] ``` ### Options ``` -a, --all display all variables (-A,-X) -T, --tree display the variables in a tree-like format -J, --json display the variables in JSON format --deprecated include deprecated variables while listing -e, --ignore ignore unknown variable errors -N, --names print only variable names -n, --values print only variable values -b, --binary print only variable values without new line -p, --load read values from file (-f) -S, --system read values from all system directories -r, --pattern use a regex for matching variable names -q, --quiet do not print variable after the value is set -w, --write only enable writing a value to variable -E, --explain provide a detailed explanation for variable -D, --docs set the path of the kernel documentation -P, --no-pager do not pipe output into a pager -v, --verbose enable verbose logging --tui show terminal user interface -c, --config set the path of the configuration file -h, --help display this help and exit (-d) -V, --version output version information and exit ``` Most of the arguments/flags are inherited from `sysctl` so they have the same functionality. ### Examples #### Listing parameters ```sh # list all parameters systeroid -A # list parameters in a tree-like format systeroid -T # list parameters in JSON format systeroid -J ``` To disable colors, set the [`NO_COLOR`](https://no-color.org/) environment variable. #### Filtering by section ```sh # only list parameters in the "kernel" section systeroid kernel # only list parameters in the "vm" and "user" sections systeroid vm user ``` #### Displaying values ```sh # print the name and value of a parameter (in "name=value" format) systeroid kernel.hostname # print only the value of a parameter systeroid -n kernel.hostname # print the name and values of the multiple parameters systeroid kernel.hostname user.max_user_namespaces ``` #### Setting values ```sh # set the value of a parameter systeroid kernel.domainname="example.com" # set the values of multiple parameters and ignore errors systeroid -e kernel.dmesg_restrict=0 vm.panic_on_oom=1 unknown_param="test" # set the values of multiple parameters and enforce the "name=value" format systeroid -w fs.dir-notify-enable=1 net.mptcp.enabled=1 vm.oom_kill_allocating_task ``` #### Loading values from a file Parameter values can be set from an [INI file](https://en.wikipedia.org/wiki/INI_file). `sysctl.conf`: ```ini # Use kernel.sysrq = 1 to allow all keys. # See https://www.kernel.org/doc/html/latest/admin-guide/sysrq.html for a list # of values and keys. kernel.sysrq = 16 # Append the PID to the core filename kernel.core_uses_pid = 1 ; Enable hard and soft link protection ; (If a line begins with a single '-', any attempts to set the value that fail will be ignored.) -fs.protected_hardlinks = 1 fs.protected_symlinks = 1 ``` To load it: ```sh systeroid --load sysctl.conf ``` If no file is given, values are loaded from `/etc/sysctl.conf` as default: ```sh systeroid --load ``` Specifying "-" as file name means reading data from standard input: ```sh systeroid --load - ``` #### Loading values from the system directories The list of default system directories are the following: - `/etc/sysctl.d` - `/run/sysctl.d` - `/usr/local/lib/sysctl.d` - `/usr/lib/sysctl.d` - `/lib/sysctl.d` - `/etc/sysctl.conf` Use `--system` flag to load the files with ".conf" extension in these directories: ```sh systeroid --system ``` #### Searching parameters ```sh # search parameters using regex patterns systeroid -r 'net.ipv4.conf.(eth|wlan)0.arp' systeroid -r '^net.ipv6' ``` Example output of combining search with listing: ```sh $ systeroid --names --pattern 'kernel.*_max$' --tree kernel ├── ngroups_max ├── pid_max └── sched_util_clamp_max ``` #### Showing information about parameters **systeroid** can dump the parameter information from the kernel documentation. This is useful if you don't know what a parameter is used for. ```sh # show information about a parameter systeroid --explain oom_dump_tasks ``` Kernel documentation should be present in one of the following paths for parsing upon first launch: - `/usr/share/doc/linux` - `/usr/share/doc/linux-doc` - `/usr/share/doc/linux-docs` - `/usr/share/doc/kernel-doc-*/Documentation` Then the parsed data is cached in `$HOME/.cache/systeroid-core` and used from there as long as the documentation is not updated. The caching mechanism can be disabled via setting the `NO_CACHE` environment variable. This is a design choice due to the fact that different versions of kernels might be installed on different systems so the documentation might be too new or old if **systeroid** was to be shipped with a fixed set of parameter descriptions bundled in. With the parsing approach, documentation is always kept up-to-date. However, this means you need to: - either install the kernel documentation package (based on your distribution) - on Arch Linux: `pacman -S linux-docs` - on Debian/Ubuntu: `apt-get install linux-doc` - on Fedora: `dnf install kernel-doc` - or explicitly specify the path of the [kernel documentation](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/admin-guide). ```sh # specify the kernel documentation path explicitly # (not needed if you have the kernel documentation installed as a package) systeroid -E user.max_user_namespaces --docs /usr/share/doc/linux ``` To change the default pager (`less(1)`), you can use the `PAGER` environment variable. Also, you can simply use `--no-pager` flag to disable it. ```sh systeroid -E kernel.ctrl-alt-del --no-pager ``` It is also possible to retrieve information about multiple parameters: ```sh systeroid -E --pattern '.*ipv4.*' --no-pager ``` #### Verbose logging `--verbose` flag can be used to enable verbose logging: ```sh systeroid --verbose ``` Also, `RUST_LOG` environment variable can be set accordingly to filter based on different log levels. ```sh RUST_LOG=trace systeroid ``` ## TUI ### Usage ``` systeroid-tui [options] ``` ``` -t, --tick-rate set the tick rate of the terminal [default: 250] -D, --docs set the path of the kernel documentation --save-path set the path for saving the changed parameters -s, --section

set the section to filter -q, --query set the query to search --bg-color set the background color [default: black] --fg-color set the foreground color [default: white] -n, --no-docs do not show the kernel documentation --deprecated include deprecated variables while listing -c, --config set the path of the configuration file -h, --help display this help and exit -V, --version output version information and exit ``` ### Key Bindings | Key | Action | | ---------------------------------------------------------- | ---------------------------- | | ?, f1 | show help | | up/down, k/j, pgup/pgdown | scroll list | | t/b | scroll to top/bottom | | left/right, h/l | scroll documentation | | tab, ` | next/previous section | | : | command | | / | search | | enter | select / set parameter value | | s | save parameter value | | c | copy to clipboard | | ctrl-l, f2 | show logs | | r, f5 | refresh | | esc | cancel / exit | | q, ctrl-c/ctrl-d | exit | ### Examples #### Launching Simply run `systeroid-tui` to launch the terminal user interface. Alternatively, you can use `systeroid --tui` command (which runs `systeroid-tui` under the hood if it is found in [`PATH`]()). #### Showing help Help menu and key bindings can be shown via pressing ?:  #### Scrolling Use up/down keys to scroll the parameter list. Alternatively, use t/b to scroll to the top/bottom.  Use left/right to scroll the parameter documentation.  #### Toggling the kernel section Press tab or ` to toggle the kernel section for filtering entries in the parameter list. Order of the sections is `all`-`abi`-`fs`-`kernel`-`net`-`sunrpc`-`user`-`vm`.  `--section` argument can be used to start **systeroid-tui** with the specified section for filtering. ```sh systeroid-tui --section kernel ```  #### Searching Press / and type in your query to search for parameters.  Alternatively, you can start **systeroid-tui** with a pre-defined search query by using `--query` argument. ```sh systeroid-tui --query "fs.quota" ```  #### Setting values Press enter to select a parameter and set its value via command prompt.  You can press r to refresh the values in the parameter list. #### Saving values Press s to set a parameter value via command prompt and save its value to a file specified via `--save-path`.  Default save path is `/etc/sysctl.conf` and the values can be loaded via `systeroid --load`. ```sh $ systeroid-tui --save-path /etc/sysctl.d/custom.conf $ systeroid --system ``` #### Running commands Press : to open the command prompt for running a command. Available commands are: | Command | Description | | ------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- | | `:help` | show help | | `:search` | enable search | | `:select` | select the current parameter in the list | | `:set ` | set parameter value | | `:save ` | save parameter value to file | | `:scroll [area] [direction] ` | scroll the list or text
- areas: `list`, `docs`, `section`
- directions: `up`, `down`, `top`, `bottom`, `right`, `left` | | `:copy` | copy to clipboard | | `:logs` | show logs | | `:refresh` | refresh values | | `:quit`, `:q` | quit | #### Copying to clipboard Press c to show the options menu for copying the name, value, or documentation of the selected parameter.  \* **systeroid-tui** should be built with `clipboard` feature for enabling the clipboard support. #### Changing the colors Use `--bg-color` and `--fg-color` arguments to customize the colors of the terminal user interface. ```sh # use a color name for setting the foreground color systeroid-tui --fg-color blue # use hexadecimal values for setting foreground/background colors systeroid-tui --bg-color ffff99 --fg-color 003366 ```  #### Viewing the parameter documentation To view the documentation as parameters are being selected on the list, kernel documentation should be parsed as explained in the "[Showing information about parameters](#showing-information-about-parameters)" section. A specific path for kernel documentation can be given via `--docs` argument or `KERNEL_DOCS` environment variable if it is not found in one of the locations that are checked as default. To disable this feature altogether, use `--no-docs` flag. #### Setting the refresh rate It is possible to specify a value in milliseconds via `--tick-rate` argument for tweaking the refresh rate of the terminal which might be necessary in some cases where better performance is desired. ```sh systeroid-tui --tick-rate 500 ``` #### Logging To view the log messages, press ctrl-l. It will bring up a pane in the TUI for analyzing the logs:  This pane consists of two parts. Left is the target selector and on the right side the logging messages view scrolling up. The target selector controls: - Capturing of log messages by the logger. - Selection of levels for display in the logging message view. The two columns have the following meaning: - Code `EWIDT`: `E` stands for Error, `W` for Warn, and similarly Info, Debug and Trace. - Inverted characters (EWIDT) are enabled log levels in the view. - Normal characters show enabled capturing of a log level per target. - If any of EWIDT are not shown, then the respective log level is not captured. This logger pane has the following key bindings and they are only activated while the logs are being shown: | Key | Action | | ------------------- | -------------------------------------------------------------- | | h | toggles target selector widget hidden/visible | | f | toggle focus on the selected target only | | up | select previous target in target selector widget | | down | select next target in target selector widget | | left | reduce SHOWN (!) log messages by one level | | right | increase SHOWN (!) log messages by one level | | - | reduce CAPTURED (!) log messages by one level | | + | increase CAPTURED (!) log messages by one level | | pageup | enter Page Mode and scroll approx. half page up in log history | | pagedown | only in page mode: scroll 10 events down in log history | | escape | exit page mode and go back to scrolling mode | | space | toggles hiding of targets, which have logfilter set to off | For saving the logs to a file, you can use the `--log-file` argument: ```sh systeroid-tui --log-file systeroid.log ``` `RUST_LOG` environment variable can be used to set the log level accordingly. ```sh RUST_LOG=debug systeroid-tui ``` ## Configuration **systeroid** can be configured with a configuration file that uses the [INI format](https://en.wikipedia.org/wiki/INI_file). It can be specified via `--config` or `SYSTEROID_CONFIG` environment variable. It can also be placed in one of the following global locations: - `$HOME/.config/systeroid/systeroid.conf` - `$HOME/.systeroid/systeroid.conf` ```sh # set the config path via argument systeroid --config config/systeroid.conf # set the config path via env SYSTEROID_CONFIG=config/systeroid.conf systeroid # use a global path mkdir -p "$HOME/.config/systeroid" cp config/systeroid.conf "$HOME/.config/systeroid" systeroid ``` See the example [systeroid.conf](./config/systeroid.conf) for the configuration options. ## Resources ### References - [sysctl - source code](https://gitlab.com/procps-ng/procps/-/blob/newlib/sysctl.c) - [sysctl - Wikipedia](https://en.wikipedia.org/wiki/Sysctl) - [sysctl - ArchWiki](https://wiki.archlinux.org/title/Sysctl) ### Logo **systeroid** logo was originally painted by [Ryan Tippery](https://ryantippery.com) as a part of the [Compositions](https://ryantippery.com/art/compositions) art collection and it is put together by me using the [Filled Spots](https://www.fontspace.com/filled-spots-font-f30755) font. Shout out to Ryan for letting me use his painting for the logo! **<3** Kudos! ### Social Links - [](https://twitter.com/systeroid) - [](https://orhun.dev) - [](https://github.com/orhun) - [](https://twitter.com/orhunp_) ### In The Media - [Systeroid: Best Way To Set Linux Kernel Parameters (YouTube / Brodie Robertson)](https://www.youtube.com/watch?v=v3q707TRIIs) ### Funding If you find **systeroid** and/or other projects on my [GitHub profile](https://github.com/orhun/) useful, consider supporting me on [GitHub Sponsors](https://github.com/sponsors/orhun) or [becoming a patron](https://www.patreon.com/join/orhunp)! [](https://patreon.com/join/orhunp) [](https://patreon.com/join/orhunp) ## Contributing See our [Contribution Guide](./CONTRIBUTING.md) and please follow the [Code of Conduct](./CODE_OF_CONDUCT.md) in all your interactions with the project. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache 2.0 License, shall be dual licensed as above, without any additional terms or conditions. ## License Licensed under either of [Apache License Version 2.0](http://www.apache.org/licenses/LICENSE-2.0) or [The MIT License](http://opensource.org/licenses/MIT) at your option. ## Copyright Copyright © 2022-2023, [Orhun Parmaksız](mailto:orhunparmaksiz@gmail.com)