GNU Core Utilities

The GNU Core Utilities or coreutils is a package of GNU software containing implementations for many of the basic tools, such as cat, ls, and rm, which are used on Unix-like operating systems.
— Wikipedia

Here I store basic coreutils and similar tools that I use on a daily basis. A lot of these commands also usually exist in this Unix commands list.

Source code of coreutils can be found at gnu.org website: coreutils.git

• write flashcards

File utilities

• chcon - Changes file security context (SELinux)
• chgrp - Changes file group ownership
• chown - Changes file ownership
• chmod - Changes the permissions of a file or directory
• cp - Copies a file or directory
• dd - Copies and converts a file
• df - Shows disk free space on file systems
• dir - Is exactly like “ls -C -b”. (Files are by default listed in columns and sorted vertically.)
• dircolors - Set up color for ls
• install - Copies files and set attributes
• ln - Creates a link to a file
• ls - Lists the files in a directory
• mkdir - Creates a directory
• mkfifo - Makes named pipes (FIFOs)
• mknod - Makes block or character special files
• mktemp - Creates a temporary file or directory
• mv - Moves files or rename files
• realpath - Returns the resolved absolute or relative path for a file
• rm - Removes (deletes) files, directories, device nodes and symbolic links
• rmdir - Removes empty directories
• shred - Overwrites a file to hide its contents, and optionally deletes it
• sync - Flushes file system buffers
• touch - Changes file timestamps; creates file
• truncate - Shrink or extend the size of a file to the specified size
• vdir - Is exactly like “ls -l -b”. (Files are by default listed in long format.)

Text utilities

• b2sum - Computes and checks BLAKE2b message digest
• base32 - Encodes or decodes Base32, and prints result to standard output
• base64 - Encodes or decodes Base64, and prints result to standard output
• cat - Concatenates and prints files on the standard output
• cksum - Checksums (IEEE Ethernet CRC-32) and count the bytes in a file.
• Supersedes other sum utilities with -a option from version 9.0.
• comm - Compares two sorted files line by line
• csplit - Splits a file into sections determined by context lines
• cut - Removes sections from each line of files
• expand - Converts tabs to spaces
• fmt - Simple optimal text formatter
• fold - Wraps each input line to fit in specified width
• head - Outputs the first part of files
• join - Joins lines of two files on a common field
• md5sum - Computes and checks MD5 message digest
• nl - Numbers lines of files
• numfmt - Reformat numbers
• od - Dumps files in octal and other formats
• paste - Merges lines of files
• ptx - Produces a permuted index of file contents
• pr - Converts text files for printing
• sha1sum, sha224sum, sha256sum, sha384sum, sha512sum - Computes and
• checks SHA-1/SHA-2 message digests
• shuf - generate random permutations
• sort - sort lines of text files
• split - Splits a file into pieces
• sum - Checksums and counts the blocks in a file
• tac - Concatenates and prints files in reverse order line by line
• tail - Outputs the last part of files
• tr - Translates or deletes characters
• tsort - Performs a topological sort
• unexpand - Converts spaces to tabs
• uniq - Removes duplicate lines from a sorted file
• wc - Prints the number of bytes, words, and lines in files

Shell utilities

• arch - Prints machine hardware name (same as uname -m)
• basename - Removes the path prefix from a given pathname
• chroot - Changes the root directory
• date - Prints or sets the system date and time
  • Prints the date and time in UTC: date -u
• dirname - Strips non-directory suffix from file name
• du - Shows disk usage on file systems
• echo - Displays a specified line of text
• env - Displays and modifies environment variables
• expr - Evaluates expressions
• factor - Factors numbers
• false - Does nothing, but exits unsuccessfully
• groups - Prints the groups of which the user is a member
• hostid - Prints the numeric identifier for the current host
• id - Prints real or effective UID and GID
• link - Creates a link to a file
• logname - Print the user’s login name
• nice - Modifies scheduling priority
• nohup - Allows a command to continue running after logging out
• nproc - Queries the number of (active) processors
• pathchk - Checks whether file names are valid or portable
• pinky - A lightweight version of finger
• printenv - Prints environment variables
• printf - Formats and prints data
• pwd - Prints the current working directory
• readlink - Displays value of a symbolic link, very useful to copy file path
  • The realpath command without options, operates like readlink in canonicalize mode.
  • Get the actual file to which symlink points: readlink path/to/file/
  • Get absolute path of file: readlink -f/--canonicalize path/to/file/
• runcon - Run command with specified security context
• seq - Prints a sequence of numbers
• sleep - Delays for a specified amount of time
• stat - Returns data about an inode
• stdbuf - Controls buffering for commands that use stdio
• stty - Changes and prints terminal line settings
• tee - Sends output to multiple files
• test - Evaluates an expression
• timeout - Run a command with a time limit
• true - Does nothing, but exits successfully
• tty - Prints terminal name
• uname - Prints system information
• unlink - Removes the specified file using the unlink function
• uptime - Tells how long the system has been running
• users - Prints the user names of users currently logged into the current host
• who - Prints a list of all users currently logged in
• whoami - Prints the effective userid
• yes - Prints a string repeatedly

Other Utilities

• [ - A synonym for test; this program permits expressions like [ expression ].

GNU binutils

The GNU Binary Utilities, or binutils, are a set of programming tools for creating and managing binary programs, object files, libraries, profile data, and assembly source code.
— Wikipedia

Website.

• as - assembler popularly known as GAS (GNU Assembler)
• ld - linker
• gprof - profiler
• addr2line - convert address to file and line
• ar - create, modify, and extract from archives
• c++filt - demangling filter for C++ symbols
• dlltool - creation of Windows dynamic-link libraries
• gold - alternative linker for ELF files
• nlmconv - object file conversion to a NetWare Loadable Module
• nm - list symbols exported by object file
• objcopy - copy object files, possibly making changes
• objdump - dump information about object files
• ranlib - generate indices for archives (for compatibility; same as ar -s)
• readelf - display content of ELF files
• size - list total and section sizes
• strings - list printable strings
• strip - remove symbols from an object file
• windmc - generates Windows message resources
• windres - compiler for Windows resource files

Other

• GNU Sed
• GNU Readline
• GPG
• GNU Debugger

lsof (LiSt Open Files)

lsof is a command for LiSting Open Files. You can use lsof for example to:

• Find uses of a specific open file: lsof /path/to/file
• Find an unlinked open file: lsof +L1
• Find processes blocking umount: lsof /mnt
• Find tcp/udp sockets: lsof -i
• Find files open to a process with known PID: lsof -p 1234
• Find files open to a named command: lsof -c bash
• Find files open by a specific user: lsof -u somebody

External links

• GNU Coreutils Cheat Sheet
• GCC