GNU Core Utils
12 min read
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