knowledge/technology/applications/cli/system/Core Utils.md

obj	website	repo	wiki	rev
application	https://www.gnu.org/software/coreutils/	https://git.savannah.gnu.org/git/coreutils.git	https://en.wikipedia.org/wiki/GNU_Core_Utilities	2024-08-26

GNU Core Utils

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.

base64

base64 encode/decode data and print to standard output

Usage: base64 [OPTION]... [FILE]

Flags

Flag	Description
-d, --decode	Decode Input
-i, --ignore-garbage	when decoding, ignore non-alphabet characters

basename

strip directory and suffix from filenames
Usage: basename NAME

cat

concatenate files and print on the standard output
Usage: cat [OPTION]... [FILE]...

Flags

Flag	Description
-b, --number-nonblank	number nonempty output lines, overrides -n
-n, --number	number all output lines

cd

change current working directory
Usage: cd [dir]
Go to home directory of current user: cd
Go up to the parent of the current directory: cd ..
Go to the previously chosen directory: cd -

chmod

change file mode (permissions) bits
Usage: chmod [OPTION]... OCTAL-MODE FILE...

Options

Option	Description
-c, --changes	like verbose but report only when a change is made
-f, --silent, --quiet	suppress most error messages
-v, --verbose	output a diagnostic for every file processed
--reference=RFILE	use RFILE's mode instead of specifying MODE values. RFILE is always dereferenced if a symbolic link.
-R, --recursive	change files and directories recursively

chown

change file owner and group
Usage: chown [OPTION]... [OWNER][:[GROUP]] FILE...

Options

Option	Description
-c, --changes	like verbose but report only when a change is made
-f, --silent, --quiet	suppress most error messages
-v, --verbose	output a diagnostic for every file processed
--reference=RFILE	use RFILE's owner and group rather than specifying OWNER:GROUP values. RFILE is always dereferenced.
-R, --recursive	operate on files and directories recursively

chroot

run command or interactive shell with special root directory
Usage: chroot [OPTION] NEWROOT [COMMAND [ARG]...]

cksum

compute and verify file checksums
Usage: cksum [OPTION]... [FILE]...

Options

Option	Description
-a, --algorithm=TYPE	select the digest type to use

Digests

• crc
• md5
• sha1
• sha224
• sha256
• sha384
• sha512
• blake2b

cp

copy files and directories
Usage: cp [OPTION]... SOURCE DEST

Options

Option	Description
-l, --link	hard link files instead of copying
-R, -r, --recursive	copy directories recursively
-s, --symbolic-link	make symbolic links instead of copying
-S, --suffix=SUFFIX	override the usual backup suffix
-t, --target-directory=DIRECTORY	copy all SOURCE arguments into DIRECTORY
--update[=UPDATE]	control which existing files are updated; UPDATE={all,none,older(default)}.
-u	equivalent to --update[=older]
-v, --verbose	explain what is being done
-x, --one-file-system	stay on this file system
-b	Create a backup file if destination already exists

cut

remove sections from each line of files
Usage: cut OPTION... [FILE]...

Options

Option	Description
-d, --delimiter=DELIM	use DELIM instead of TAB for field delimiter
-f, --fields=LIST	select only these fields; also print any line that contains no delimiter character, unless the -s option is specified
-s, --only-delimited	do not print lines not containing delimiters
--output-delimiter=STRING	use STRING as the output delimiter the default is to use the input delimiter

date

print or set the system date and time
Usage: date [OPTION]... [+FORMAT]

Options

Option	Description
-d, --date=STRING	display time described by STRING
-r, --reference=FILE	display the last modification time of FILE
-s, --set=STRING	set time described by STRING
-u, --utc, --universal	print or set Coordinated Universal Time (UTC)
--iso	print ISO date (YYYY-MM-DD)

dd

convert and copy a file
Usage: dd [OPERAND]...

Operands

Operand	Description
bs=BYTES	read and write up to BYTES bytes at a time (default: 512)
count=N	copy only N input blocks
if=FILE	read from FILE instead of stdin
of=FILE	write to FILE instead of stdout
status=LEVEL	The LEVEL of information to print to stderr; 'none' suppresses everything but error messages, 'noxfer' suppresses the final transfer statistics, 'progress' shows periodic transfer statistics

df

report file system space usage
Usage: df [OPTION]... [FILE]...

Options

Option	Description
-a, --all	include pseudo, duplicate, inaccessible file systems
-h, --human-readable	print sizes in powers of 1024 (e.g., 1023M)
-H, --si	print sizes in powers of 1000 (e.g., 1.1G)
-i, --inodes	list inode information instead of block usage

dirname

strip last component from file name
Usage: dirname [OPTION] NAME...

du

estimate file space usage
Usage: du [OPTION]... [FILE]...

Options

Option	Description
-h, --human-readable	print sizes in human readable format
-s, --summarize	display only a total for each argument

echo

display a line of text
Usage: echo [OPTION]... [STRING]...

Options

Option	Description
-n	do not output the trailing newline
-e	enable interpretation of backslash escapes
-E	disable interpretation of backslash escapes (default)

Backslash Interpretations

Sequence	Meaning
\	backslash
\a	alert (BEL)
\b	backspace
\c	produce no further output
\e	escape
\f	form feed
\n	new line
\r	carriage return
\t	horizontal tab
\v	vertical tab
\0NNN	byte with octal value NNN (1 to 3 digits)
\xHH	byte with hexadecimal value HH (1 to 2)

env

run a program in a modified environment
Print Environment Variables with only env
Usage: env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]

Options

Option	Description
-i, --ignore-environment	start with an empty environment
-u, --unset=NAME	remove variable from the environment
-C, --chdir=DIR	change working directory to DIR
--block-signal[=SIG]	block delivery of SIG signal(s) to COMMAND
--ignore-signal[=SIG]	set handling of SIG signal(s) to do nothing
-v, --debug	print verbose information for each processing step

false

do nothing, unsuccessfully
Usage: false

head

output the first part of files
Usage: head [OPTION]... [FILE]...

Options

Option	Description
-c, --bytes=[-]NUM	print the first NUM bytes of each file; with the leading '-', print all but the last NUM bytes of each file
-n, --lines=[-]NUM	print the first NUM lines instead of the first 10; with the leading '-', print all but the last NUM lines of each file
-q, --quiet, --silent	never print headers giving file names

id

print real and effective user and group IDs
Usage: id [OPTION]... [USER]...

Option

Option	Description
-g, --group	print only the effective group ID
-G, --groups	print all group IDs
-n, --name	print a name instead of a number, for -ugG
-u, --user	print only the effective user ID

install

copy files and set attributes
Usage: install [OPTION]... SOURCE... DIRECTORY

Options

Option	Description
-b	make a backup of each existing destination file
-S, --suffix=SUFFIX	override the usual backup suffix
-C, --compare	compare content of source and destination files, and if no change to content, ownership, and permissions, do not modify the destination at all
-d, --directory	treat all arguments as directory names; create all components of the specified directories
-g, --group=GROUP	set group ownership, instead of process' current group
-m, --mode=MODE	set permission mode (as in chmod), instead of rwxr-xr-x
-o, --owner=OWNER	set ownership (super-user only)
-p, --preserve-timestamps	apply access/modification times of SOURCE files to corresponding destination files
-s, --strip	strip symbol tables
-t, --target-directory=DIRECTORY	copy all SOURCE arguments into DIRECTORY
-v, --verbose	print the name of each created file or directory

kill

terminate a process
Usage: kill [-signal|-s signal|-p] [-q value] [-a] [--timeout milliseconds signal] [--] pid|name...

Options

Option	Description
-s, --signal signal	The signal to send. It may be given as a name or a number.
-p, --pid	Only print the process ID (PID) of the named processes, do not send any signals.
--verbose	Print PID(s) that will be signaled with kill along with the signal.

ln

make links between files
Usage: ln [OPTION]... TARGET LINK_NAME

Options

Option	Description
-s, --symbolic	make symbolic links instead of hard links
-t, --target-directory=DIRECTORY	specify the DIRECTORY in which to create the links
-v, --verbose	print name of each linked file

ls

list directory contents
Usage: ls [OPTION]... [FILE]...

Options

Option	Description
-a, --all	do not ignore entries starting with .
-h, --human-readable	with -l print sizes like 1K 234M 2G etc
-I, --ignore=PATTERN	do not list implied entries matching shell PATTERN
-l	use a long listing format
-r, --reverse	reverse order while sorting
-R, --recursive	list subdirectories recursively

mkdir

make directories
Usage: mkdir [OPTION]... DIRECTORY...

Options

Option	Description
-m, --mode=MODE	set file mode (as in chmod), not a=rwx - umask
-p, --parents	no error if existing, make parent directories as needed, with their file modes unaffected by any -m option.
-v, --verbose	print a message for each created directory

mkfifo

make FIFOs (named pipes)
Usage: mkfifo [OPTION]... NAME...

mv

move (rename) files
Usage: mv [OPTION]... SOURCE... DIRECTORY

Options

Option	Description
-b	make a backup of each existing destination file
-S, --suffix=SUFFIX	override the usual backup suffix
-t, --target-directory=DIRECTORY	copy all SOURCE arguments into DIRECTORY
-v, --verbose	print the name of each created file or directory

nl

number lines of files
Usage: nl [FILE]...

nproc

print the number of processing units available
Usage: nproc

pwd

print name of current/working directory
Usage: pwd

passwd

Change a users password
Usage: passwd [user]

readlink

print resolved symbolic links or canonical file names
Usage: readlink [OPTION]... FILE...

Options

Option	Description
-f, --canonicalize	canonicalize by following every symlink in every component of the given name recursively; all but the last component must exist
-e, --canonicalize-existing	canonicalize by following every symlink in every component of the given name recursively, all components must exist
-m, --canonicalize-missing	canonicalize by following every symlink in every component of the given name recursively, without requirements on components existence
-n, --no-newline	do not output the trailing delimiter

realpath

print the resolved path
Usage: realpath [OPTION]... FILE...

Options

Option	Description
-e, --canonicalize-existing	all components of the path must exist
-m, --canonicalize-missing	no path components need exist or be a directory
-L, --logical	resolve '..' components before symlinks
--relative-to=DIR	print the resolved path relative to DIR
--relative-base=DIR	print absolute paths unless paths below DIR
-s, --strip, --no-symlinks	don't expand symlinks

rm

remove files or directories
Usage: rm [OPTION]... [FILE]...

Options

Option	Description
-f, --force	ignore nonexistent files and arguments, never prompt
-i	prompt before every removal
--one-file-system	when removing a hierarchy recursively, skip any directory that is on a file system different from that of the corresponding command line argument
-r, -R, --recursive	remove directories and their contents recursively
-d, --dir	remove empty directories
-v, --verbose	explain what is being done

rmdir

remove empty directories
Usage: rmdir [OPTION]... DIRECTORY...

Options

Option	Description
-p, --parents	remove DIRECTORY and its ancestors; e.g., 'rmdir -p a/b' is similar to 'rmdir a/b a'
-v, --verbose	output a diagnostic for every directory processed

seq

print a sequence of numbers
Usage:

• seq [OPTION]... LAST
• seq [OPTION]... FIRST LAST
• seq [OPTION]... FIRST INCREMENT LAST

Options

Option	Description
-f, --format=FORMAT	use printf style floating-point FORMAT
-s, --separator=STRING	use STRING to separate numbers (default: \n)
-w, --equal-width	equalize width by padding with leading zeroes

shred

overwrite a file to hide its contents, and optionally delete it
Usage: shred [OPTION]... FILE...

Options

Option	Description
-f, --force	change permissions to allow writing if necessary
-n, --iterations=N	overwrite N times instead of the default (3)
--random-source=FILE	get random bytes from FILE

shuf

generate random permutations
Usage: shuf [OPTION]... [FILE]

Options

Option	Description
-i, --input-range=LO-HI	treat each number LO through HI as an input line
-n, --head-count=COUNT	output at most COUNT lines
-o, --output=FILE	write result to FILE instead of standard output
--random-source=FILE	get random bytes from FILE
-r, --repeat	output lines can be repeated

sleep

delay for a specified amount of time
Usage: sleep NUMBER[SUFFIX]...

sort

sort lines of text files
Usage: sort [OPTION]... [FILE]...

Options

Option	Description
-b, --ignore-leading-blanks	ignore leading blanks
-d, --dictionary-order	consider only blanks and alphanumeric characters
-f, --ignore-case	fold lower case to upper case characters
-g, --general-numeric-sort	compare according to general numerical value
-i, --ignore-nonprinting	consider only printable characters
-M, --month-sort	compare (unknown) < 'JAN' < ... < 'DEC'
-h, --human-numeric-sort	compare human readable numbers (e.g., 2K 1G)
-n, --numeric-sort	compare according to string numerical value
-r, --reverse	reverse the result of comparisons

split

split a file into pieces
Usage: split [OPTION]... [FILE [PREFIX]]

Options

Option	Description
-a, --suffix-length=N	generate suffixes of length N (default 2)
--additional-suffix=SUFFIX	append an additional SUFFIX to file names
-b, --bytes=SIZE	put SIZE bytes per output file
-C, --line-bytes=SIZE	put at most SIZE bytes of records per output file
-d	use numeric suffixes starting at 0, not alphabetic
--numeric-suffixes[=FROM]	same as -d, but allow setting the start value
-x	use hex suffixes starting at 0, not alphabetic
--hex-suffixes[=FROM]	same as -x, but allow setting the start value
-l, --lines=NUMBER	put NUMBER lines/records per output file
-n, --number=CHUNKS	generate CHUNKS output files; see explanation below
--verbose	print a diagnostic just before each output file is opened

stat

display file or file system status
Usage: stat [OPTION]... FILE...

Options

Option	Description
-L, --dereference	follow links
-f, --file-system	display file system status instead of file status
-c --format=FORMAT	use the specified FORMAT instead of the default; output a newline after each use of FORMAT

Format Modifiers

Format	Description
%a	permission bits in octal (note '#' and '0' printf flags)
%A	permission bits and file type in human readable form
%b	number of blocks allocated (see %B)
%B	the size in bytes of each block reported by %b
%C	SELinux security context string
%d	device number in decimal (st_dev)
%D	device number in hex (st_dev)
%Hd	major device number in decimal
%Ld	minor device number in decimal
%f	raw mode in hex
%F	file type
%g	group ID of owner
%G	group name of owner
%h	number of hard links
%i	inode number
%m	mount point
%n	file name
%N	quoted file name with dereference if symbolic link
%o	optimal I/O transfer size hint
%s	total size, in bytes
%r	device type in decimal (st_rdev)
%R	device type in hex (st_rdev)
%Hr	major device type in decimal, for character/block device special files
%Lr	minor device type in decimal, for character/block device special files
%t	major device type in hex, for character/block device special files
%T	minor device type in hex, for character/block device special files
%u	user ID of owner
%U	user name of owner
%w	time of file birth, human-readable; - if unknown
%W	time of file birth, seconds since Epoch; 0 if unknown
%x	time of last access, human-readable
%X	time of last access, seconds since Epoch
%y	time of last data modification, human-readable
%Y	time of last data modification, seconds since Epoch
%z	time of last status change, human-readable
%Z	time of last status change, seconds since Epoch
%a	free blocks available to non-superuser
%b	total data blocks in file system
%c	total file nodes in file system
%d	free file nodes in file system
%f	free blocks in file system
%i	file system ID in hex
%l	maximum length of filenames
%n	file name
%s	block size (for faster transfers)
%S	fundamental block size (for block counts)
%t	file system type in hex
%T	file system type in human readable form

tac

concatenate and print files in reverse
Usage: tac [FILE]...

tail

output the last part of files
Usage: tail [OPTION]... [FILE]...

Options

Option	Description
-c, --bytes=[+]NUM	output the last NUM bytes; or use -c +NUM to output starting with byte NUM of each file
-f	output appended data as the file grows;
-n, --lines=[+]NUM	output the last NUM lines, instead of the last 10; or use -n +NUM to skip NUM-1 lines at the start
--pid=PID	with -f, terminate after process ID, PID dies

tee

read from standard input and write to standard output and files
Usage: tee [OPTION]... [FILE]...

Options

Option	Description
-a, --append	append to the given FILEs, do not overwrite

touch

change file timestamps
Usage: touch [OPTION]... FILE...

Options

Option	Description
-a	change only the access time
-c, --no-create	do not create any files
-d, --date=STRING	parse STRING and use it instead of current time
-r, --reference=FILE	use this file's times instead of current time

tr

translate or delete characters
Usage: tr [OPTION]... STRING1 [STRING2]

Options

Option	Description
-d, --delete	delete characters in STRING1, do not translate

true

do nothing, successfully
Usage: true

truncate

shrink or extend the size of a file to the specified size
Usage: truncate OPTION... FILE...

Options

Option	Description
-c, --no-create	do not create any files
-r, --reference=RFILE	base size on RFILE
-s, --size=SIZE	set or adjust the file size by SIZE bytes

uname

print system information
Usage: uname [OPTION]...

Options

Option	Description
-a, --all	print all information
-s, --kernel-name	print the kernel name
-n, --nodename	print the network node hostname
-r, --kernel-release	print the kernel release
-v, --kernel-version	print the kernel version
-m, --machine	print the machine hardware name

uniq

report or omit repeated lines
Usage: uniq [OPTION]... [INPUT [OUTPUT]]

Options

Option	Description
-c, --count	prefix lines by the number of occurrences
-d, --repeated	only print duplicate lines, one for each group
-i, --ignore-case	ignore differences in case when comparing
-s, --skip-chars=N	avoid comparing the first N characters
-u, --unique	only print unique lines

uptime

Tell how long the system has been running
Usage: uptime [options]

Options

Option	Description
-p, --pretty	show uptime in pretty format
-s, --since	system up since, in yyyy-mm-dd HH:MM:SS format

wc

print newline, word, and byte counts for each file
Usage: wc [OPTION]... [FILE]...

Options

Option	Description
-c, --bytes	print the byte counts
-m, --chars	print the character counts
-l, --lines	print the newline counts
-w, --words	print the word counts

whoami

print effective user name
Usage: whoami