Difference between revisions of "Core utilities"

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[[Category:Utilities (English)]]
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[[Category:Command-line]]
This article deals with so-called "core" utilities on a GNU/Linux system, such as '''less''', '''ls''', and '''grep'''. The scope of this article includes -- ''but is not limited to'' -- those utilities included with the GNU {{Package Official|coreutils}} package. What follows are various tips and tricks and other helpful information related to these utilities. If sections grow too detailed, please split into separate articles.
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[[Category:Lists of software]]
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[[fa:Core utilities]]
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[[ja:Core Utilities]]
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[[ko:Core utilities]]
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[[ru:Core utilities]]
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{{Related articles start}}
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{{Related|Command-line shell}}
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{{Related|Users and groups}}
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{{Related|systemd}}
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{{Related|pacman}}
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{{Related|General recommendations}}
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{{Related articles end}}
  
'''This page is currently under construction.'''
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''Core utilities'' are the basic, fundamental tools of a [[GNU]]/[[Linux]] system. This article provides an incomplete overview of them, links their documentation and describes useful alternatives. The scope of this article includes, but is not limited to, the [https://www.gnu.org/software/coreutils/coreutils.html GNU coreutils]. Most core utilities are traditional [[Wikipedia:Unix|Unix]] tools (see [[Heirloom]]) and many were standardized by [[Wikipedia:POSIX|POSIX]] but have been developed further to provide more features.
  
See also:
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Most command-line interfaces are documented in [[man page]]s, utilities by the [[GNU Project]] are documented primarily in [[Info manual]]s, some [[shell]]s provide a {{ic|help}} command for shell builtin commands. Additionally most utilities print their usage when run with the {{ic|--help}} flag.
  
* [[Commandline Tools]]
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== Essentials ==
* [[Useful Commands]]
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* [[General Recommendations]]
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The following table lists some important utilities which Arch Linux users should be familiar with. See also {{man|1|intro}}.
 +
 
 +
{| class=wikitable
 +
! Package !! Utility !! Description !! Documentation !! Alternatives
 +
|-
 +
| shell built-ins || cd || change directory || {{man|1p|cd}}
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|-
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|rowspan=12| GNU {{Pkg|coreutils}}
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| ls || list directory || {{man|1|ls}}, [https://www.gnu.org/software/coreutils/manual/html_node/ls-invocation.html info] || {{Pkg|exa}}, {{Pkg|lsd}}, {{Pkg|tree}}
 +
|-
 +
| cat || concatenate files to stdout || {{man|1|cat}}, [https://www.gnu.org/software/coreutils/manual/html_node/cat-invocation.html info] || {{man|1|tac}}, {{Pkg|bat}}
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|-
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| mkdir || make directory || {{man|1|mkdir}}, [https://www.gnu.org/software/coreutils/manual/html_node/mkdir-invocation.html info]
 +
|-
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| rmdir || remove empty directory || {{man|1|rmdir}}, [https://www.gnu.org/software/coreutils/manual/html_node/rmdir-invocation.html info]
 +
|-
 +
| rm || remove files or directories || {{man|1|rm}}, [https://www.gnu.org/software/coreutils/manual/html_node/rm-invocation.html info] || [[shred]]
 +
|-
 +
| cp || copy files or directories || {{man|1|cp}}, [https://www.gnu.org/software/coreutils/manual/html_node/cp-invocation.html info]
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|-
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| mv || move files or directories || {{man|1|mv}}, [https://www.gnu.org/software/coreutils/manual/html_node/mv-invocation.html info]
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|-
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| ln || make hard or symbolic links || {{man|1|ln}}, [https://www.gnu.org/software/coreutils/manual/html_node/ln-invocation.html info]
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|-
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| [[chown]] || change file owner and group || {{man|1|chown}}, [https://www.gnu.org/software/coreutils/manual/html_node/chown-invocation.html info] || {{man|1|chgrp}}
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|-
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| [[chmod]] || change file permissions || {{man|1|chmod}}, [https://www.gnu.org/software/coreutils/manual/html_node/chmod-invocation.html info]
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|-
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| [[dd]] || convert and copy a file || {{man|1|dd}}, [https://www.gnu.org/software/coreutils/manual/html_node/dd-invocation.html info]
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|-
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| df || report file system disk space usage || {{man|1|df}}, [https://www.gnu.org/software/coreutils/manual/html_node/df-invocation.html info]
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|-
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| GNU {{Pkg|tar}} || [[tar]] || tar archiver || {{man|1|tar}}, [https://www.gnu.org/software/tar/manual/html_chapter/index.html info] || [[archiver]]s
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|-
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| GNU {{Pkg|less}} || less || terminal pager || {{man|1|less}} || [[terminal pager]]s
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|-
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| GNU {{Pkg|findutils}} || find || search files or directories || {{man|1|find}}, [https://www.gnu.org/software/findutils/manual/html_node/find_html/index.html info], [[GregsWiki:UsingFind|GregsWiki]] || [[#find alternatives]]
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|-
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| GNU {{Pkg|diffutils}} || diff || compare files line by line || {{man|1|diff}}, [https://www.gnu.org/software/diffutils/manual/html_node/Invoking-diff.html info] || [[#diff alternatives]]
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|-
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| GNU {{Pkg|grep}} || grep || print lines matching a pattern || {{man|1|grep}}, [https://www.gnu.org/software/grep/manual/html_node/index.html info] || [[#grep alternatives]]
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|-
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| GNU {{Pkg|sed}} || sed || stream editor || {{man|1|sed}}, [https://www.gnu.org/software/sed/manual/html_node/index.html info], [http://sed.sourceforge.net/sed1line.txt one-liners]
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|-
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| GNU {{Pkg|gawk}} || awk || pattern scanning and processing language || {{man|1|gawk}}, [https://www.gnu.org/software/gawk/manual/html_node/index.html info] || {{Pkg|nawk}}, {{AUR|mawk}}
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|-
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|rowspan=6| {{Pkg|util-linux}}
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| [[Wikipedia:dmesg|dmesg]] || print or control the kernel ring buffer || {{man|1|dmesg}} || [[systemd journal]]
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|-
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| [[lsblk]] || list block devices || {{man|8|lsblk}}
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|-
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| [[mount]] || mount a filesystem || {{man|8|mount}}
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|-
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| [[umount]] || unmount a filesystem || {{man|8|umount}}
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|-
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| [[su]] || substitute user || {{man|1|su}} || [[sudo]]
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|-
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| kill || terminate a process || {{man|1|kill}} || {{man|1|pkill}}, {{man|1|killall}}
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|-
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|rowspan=3| {{Pkg|procps-ng}}
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| pgrep || look up processes by name or attributes || {{man|1|pgrep}} || {{man|1|pidof}}
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|-
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| ps || show information about processes || {{man|1|ps}} ||rowspan=2| {{man|1|top}}, {{Pkg|htop}}
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|-
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| free || display amount of free and used memory || {{man|1|free}}
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|}
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=== Preventing data loss ===
 +
 
 +
{{ic|rm}}, {{ic|mv}}, {{ic|cp}} and shell redirections happily delete or overwrite files without asking. {{ic|rm}}, {{ic|mv}}, and {{ic|cp}} all support the {{ic|-i}} flag to prompt the user before every removal / overwrite. Some users like to enable the {{ic|-i}} flag by default using [[alias]]es. Relying upon these shell options can be dangerous, because you get used to them, resulting in potential data loss when you use another system or user that does not have them. The best way to prevent data loss is to create [[backup]]s.
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 +
== Nonessentials ==
 +
 
 +
This table lists core utilities that often come in handy.
 +
 
 +
{| class=wikitable
 +
! Package !! Utility !! Description !! Documentation !! Alternatives
 +
|-
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|rowspan=3| shell built-ins
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| alias || define or display aliases || {{man|1p|alias}}
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|-
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| type || print the type of a command || {{man|1p|type}} || {{man|1|which}}
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|-
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| time || time a command || {{man|1p|time}}
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|-
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|rowspan=11| GNU {{Pkg|coreutils}}
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| tee || read stdin and write to stdout and files || {{man|1|tee}}, [https://www.gnu.org/software/coreutils/manual/html_node/tee-invocation.html info]
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|-
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| mktemp || make a temporary file or directory || {{man|1|mktemp}}, [https://www.gnu.org/software/coreutils/manual/html_node/mktemp-invocation.html info]
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|-
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| cut || print selected parts of lines || {{man|1|cut}}, [https://www.gnu.org/software/coreutils/manual/html_node/cut-invocation.html info]
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|-
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| tr || translate or delete characters || {{man|1|tr}}, [https://www.gnu.org/software/coreutils/manual/html_node/tr-invocation.html info]
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|-
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| od || dump files in octal and other formats || {{man|1|od}}, [https://www.gnu.org/software/coreutils/manual/html_node/od-invocation.html info] || {{man|1|hexdump}}, [[vim]]'s {{man|1|xxd}}
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|-
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| sort || sort lines || {{man|1|sort}}, [https://www.gnu.org/software/coreutils/manual/html_node/sort-invocation.html info]
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|-
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| uniq || report or omit repeated lines || {{man|1|uniq}}, [https://www.gnu.org/software/coreutils/manual/html_node/uniq-invocation.html info]
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|-
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| comm || compare two sorted files line by line || {{man|1|comm}}, [https://www.gnu.org/software/coreutils/manual/html_node/comm-invocation.html info]
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|-
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| head || output the first part of files || {{man|1|head}}, [https://www.gnu.org/software/coreutils/manual/html_node/head-invocation.html info]
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|-
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| tail || output the last part of files, or follow files || {{man|1|tail}}, [https://www.gnu.org/software/coreutils/manual/html_node/tail-invocation.html info]
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|-
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| wc || print newline, word and byte count || {{man|1|wc}}, [https://www.gnu.org/software/coreutils/manual/html_node/wc-invocation.html info]
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|-
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| GNU {{Pkg|binutils}} || strings || print printable characters in binary files || {{man|1|strings}}, [https://sourceware.org/binutils/docs/binutils/strings.html info]
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|-
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| GNU {{Pkg|glibc}} || iconv || convert character encodings || {{man|1|iconv}} || {{Pkg|recode}}
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|-
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| {{Pkg|file}} || file || guess file type || {{man|1|file}}
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|}
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 +
The {{Pkg|moreutils}} package provides useful tools like {{man|1|sponge}} that are missing from the GNU coreutils.
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== Alternatives ==
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 +
Alternative core utilities are provided by [[BusyBox]], the [[Heirloom|Heirloom Toolchest]], {{Pkg|9base}}, {{AUR|sbase-git}} and {{AUR|ubase-git}}.
 +
 
 +
=== cp alternatives ===
 +
 
 +
Using [[rsync#As cp/mv alternative]] allows you to resume a failed transfer, to show the transfer status, to skip already existing files and to make sure of the destination files integrity using checksums.
 +
 
 +
=== ls alternatives ===
 +
 
 +
* {{App|lsd|Modern ls with a lot of pretty colors and awesome icons. Written in Rust.|https://github.com/Peltoche/lsd|{{Pkg|lsd}}}}
 +
* {{App|exa|Another ls replacement with color support, tree view, git integration and other features. Also written in Rust.|https://github.com/ogham/exa|{{Pkg|exa}}}}
 +
 
 +
=== find alternatives ===
 +
 
 +
* {{App|fd|Simple, fast and user-friendly alternative to find. Ignores hidden and {{ic|.gitignore}}'d files by default.|https://github.com/sharkdp/fd|{{Pkg|fd}}}}
 +
* {{App|fuzzy-find|Fuzzy completion for finding files.|https://github.com/silentbicycle/ff|{{AUR|ff-git}}}}
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* {{App|[[mlocate]]|Merging locate/updatedb implementation.|https://pagure.io/mlocate|{{Pkg|mlocate}}}}
 +
 
 +
For graphical file searchers, see [[List of applications/Utilities#File searching]].
 +
 
 +
=== diff alternatives ===
 +
 
 +
While {{Pkg|diffutils}} does not provide a word-wise diff, several other programs do:
 +
 
 +
* [[git]] diff can do a word diff with {{ic|--color-words}}, using {{ic|--no-index}} it can also be used for files outside of Git working trees.
 +
* {{App|dwdiff|A word diff front-end for the diff program; supports colors.|https://os.ghalkes.nl/dwdiff.html|{{Pkg|dwdiff}}}}
 +
* {{App|GNU wdiff|A wordwise implementation of GNU diff; does not support colors.|https://www.gnu.org/software/wdiff/|{{Pkg|wdiff}}}}
 +
* {{App|cwdiff|A GNU wdiff wrapper that colorizes the output.|https://github.com/junghans/cwdiff|{{AUR|cwdiff}}, {{AUR|cwdiff-git}}}}
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* {{App|icdiff|A colorized diff tool written in Python. "Improved color diff" is meant to supplement normal diff use.|https://github.com/jeffkaufman/icdiff|{{AUR|icdiff}},{{AUR|icdiff-git}}}}
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 +
See also [[List of applications/Utilities#Comparison, diff, merge]].
 +
 
 +
=== grep alternatives ===
 +
 
 +
* {{App|mgrep|A multiline grep.|https://sourceforge.net/projects/multiline-grep/|{{AUR|mgrep}}}}
 +
 
 +
==== Code searchers ====
 +
 
 +
The following three tools aim to replace grep for code search. They do recursive search by default, skip binary files and respect {{ic|.gitignore}}.
 +
 
 +
* {{App|ack|A Perl-based grep replacement, aimed at programmers with large trees of heterogeneous source code.|https://beyondgrep.com/|{{Pkg|ack}}}}
 +
* {{App|ripgrep (rg)|A search tool that combines the usability of ag with the raw speed of grep.|https://github.com/BurntSushi/ripgrep|{{Pkg|ripgrep}}}}
 +
* {{App|The Silver Searcher (ag)|Code searching tool similar to Ack, but faster.|https://github.com/ggreer/the_silver_searcher|{{Pkg|the_silver_searcher}}}}
 +
 
 +
==== Interactive filters ====
 +
 
 +
* {{App|[[fzf]]|General-purpose command-line fuzzy finder, powered by find by default.|https://github.com/junegunn/fzf|{{Pkg|fzf}}, {{AUR|fzf-git}}}}
 +
* {{App|fzy|A fast, simple fuzzy text selector with an advanced scoring algorithm.|https://github.com/jhawthorn/fzy|{{Pkg|fzy}}, {{AUR|fzy-git}}}}
 +
* {{App|peco|Simplistic interactive filtering tool.|https://github.com/peco/peco|{{AUR|peco}}, {{AUR|peco-git}}}}
 +
* {{App|percol|Adds flavor of interactive filtering to the traditional pipe concept of the UNIX shell.|https://github.com/mooz/percol|{{Pkg|percol}}, {{AUR|percol-git}}}}
 +
 
 +
== See also ==
 +
 
 +
* [https://www.gnu.org/software/coreutils/manual/coreutils.html GNU Coreutils documentation]
 +
* [http://pubs.opengroup.org/onlinepubs/9699919799/idx/utilities.html POSIX utilities]

Latest revision as of 08:54, 24 January 2020

Core utilities are the basic, fundamental tools of a GNU/Linux system. This article provides an incomplete overview of them, links their documentation and describes useful alternatives. The scope of this article includes, but is not limited to, the GNU coreutils. Most core utilities are traditional Unix tools (see Heirloom) and many were standardized by POSIX but have been developed further to provide more features.

Most command-line interfaces are documented in man pages, utilities by the GNU Project are documented primarily in Info manuals, some shells provide a help command for shell builtin commands. Additionally most utilities print their usage when run with the --help flag.

Essentials

The following table lists some important utilities which Arch Linux users should be familiar with. See also intro(1).

Package Utility Description Documentation Alternatives
shell built-ins cd change directory cd(1p)
GNU coreutils ls list directory ls(1), info exa, lsd, tree
cat concatenate files to stdout cat(1), info tac(1), bat
mkdir make directory mkdir(1), info
rmdir remove empty directory rmdir(1), info
rm remove files or directories rm(1), info shred
cp copy files or directories cp(1), info
mv move files or directories mv(1), info
ln make hard or symbolic links ln(1), info
chown change file owner and group chown(1), info chgrp(1)
chmod change file permissions chmod(1), info
dd convert and copy a file dd(1), info
df report file system disk space usage df(1), info
GNU tar tar tar archiver tar(1), info archivers
GNU less less terminal pager less(1) terminal pagers
GNU findutils find search files or directories find(1), info, GregsWiki #find alternatives
GNU diffutils diff compare files line by line diff(1), info #diff alternatives
GNU grep grep print lines matching a pattern grep(1), info #grep alternatives
GNU sed sed stream editor sed(1), info, one-liners
GNU gawk awk pattern scanning and processing language gawk(1), info nawk, mawkAUR
util-linux dmesg print or control the kernel ring buffer dmesg(1) systemd journal
lsblk list block devices lsblk(8)
mount mount a filesystem mount(8)
umount unmount a filesystem umount(8)
su substitute user su(1) sudo
kill terminate a process kill(1) pkill(1), killall(1)
procps-ng pgrep look up processes by name or attributes pgrep(1) pidof(1)
ps show information about processes ps(1) top(1), htop
free display amount of free and used memory free(1)

Preventing data loss

rm, mv, cp and shell redirections happily delete or overwrite files without asking. rm, mv, and cp all support the -i flag to prompt the user before every removal / overwrite. Some users like to enable the -i flag by default using aliases. Relying upon these shell options can be dangerous, because you get used to them, resulting in potential data loss when you use another system or user that does not have them. The best way to prevent data loss is to create backups.

Nonessentials

This table lists core utilities that often come in handy.

Package Utility Description Documentation Alternatives
shell built-ins alias define or display aliases alias(1p)
type print the type of a command type(1p) which(1)
time time a command time(1p)
GNU coreutils tee read stdin and write to stdout and files tee(1), info
mktemp make a temporary file or directory mktemp(1), info
cut print selected parts of lines cut(1), info
tr translate or delete characters tr(1), info
od dump files in octal and other formats od(1), info hexdump(1), vim's xxd(1)
sort sort lines sort(1), info
uniq report or omit repeated lines uniq(1), info
comm compare two sorted files line by line comm(1), info
head output the first part of files head(1), info
tail output the last part of files, or follow files tail(1), info
wc print newline, word and byte count wc(1), info
GNU binutils strings print printable characters in binary files strings(1), info
GNU glibc iconv convert character encodings iconv(1) recode
file file guess file type file(1)

The moreutils package provides useful tools like sponge(1) that are missing from the GNU coreutils.

Alternatives

Alternative core utilities are provided by BusyBox, the Heirloom Toolchest, 9base, sbase-gitAUR and ubase-gitAUR.

cp alternatives

Using rsync#As cp/mv alternative allows you to resume a failed transfer, to show the transfer status, to skip already existing files and to make sure of the destination files integrity using checksums.

ls alternatives

  • lsd — Modern ls with a lot of pretty colors and awesome icons. Written in Rust.
https://github.com/Peltoche/lsd || lsd
  • exa — Another ls replacement with color support, tree view, git integration and other features. Also written in Rust.
https://github.com/ogham/exa || exa

find alternatives

  • fd — Simple, fast and user-friendly alternative to find. Ignores hidden and .gitignore'd files by default.
https://github.com/sharkdp/fd || fd
  • fuzzy-find — Fuzzy completion for finding files.
https://github.com/silentbicycle/ff || ff-gitAUR
  • mlocate — Merging locate/updatedb implementation.
https://pagure.io/mlocate || mlocate

For graphical file searchers, see List of applications/Utilities#File searching.

diff alternatives

While diffutils does not provide a word-wise diff, several other programs do:

  • git diff can do a word diff with --color-words, using --no-index it can also be used for files outside of Git working trees.
  • dwdiff — A word diff front-end for the diff program; supports colors.
https://os.ghalkes.nl/dwdiff.html || dwdiff
  • GNU wdiff — A wordwise implementation of GNU diff; does not support colors.
https://www.gnu.org/software/wdiff/ || wdiff
  • cwdiff — A GNU wdiff wrapper that colorizes the output.
https://github.com/junghans/cwdiff || cwdiffAUR, cwdiff-gitAUR
  • icdiff — A colorized diff tool written in Python. "Improved color diff" is meant to supplement normal diff use.
https://github.com/jeffkaufman/icdiff || icdiffAUR,icdiff-gitAUR

See also List of applications/Utilities#Comparison, diff, merge.

grep alternatives

  • mgrep — A multiline grep.
https://sourceforge.net/projects/multiline-grep/ || mgrepAUR

Code searchers

The following three tools aim to replace grep for code search. They do recursive search by default, skip binary files and respect .gitignore.

  • ack — A Perl-based grep replacement, aimed at programmers with large trees of heterogeneous source code.
https://beyondgrep.com/ || ack
  • ripgrep (rg) — A search tool that combines the usability of ag with the raw speed of grep.
https://github.com/BurntSushi/ripgrep || ripgrep
  • The Silver Searcher (ag) — Code searching tool similar to Ack, but faster.
https://github.com/ggreer/the_silver_searcher || the_silver_searcher

Interactive filters

  • fzf — General-purpose command-line fuzzy finder, powered by find by default.
https://github.com/junegunn/fzf || fzf, fzf-gitAUR
  • fzy — A fast, simple fuzzy text selector with an advanced scoring algorithm.
https://github.com/jhawthorn/fzy || fzy, fzy-gitAUR
  • peco — Simplistic interactive filtering tool.
https://github.com/peco/peco || pecoAUR, peco-gitAUR
  • percol — Adds flavor of interactive filtering to the traditional pipe concept of the UNIX shell.
https://github.com/mooz/percol || percol, percol-gitAUR

See also