Package util-linux

A collection of basic system utilities

http://en.wikipedia.org/wiki/Util-linux

The util-linux package contains a large variety of low-level system
utilities that are necessary for a Linux system to function. Among
others, Util-linux contains the fdisk configuration tool and the login
program.

General Commands (Section 1)
cal
cal displays a simple calendar. If no arguments are specified, the current month is displayed. The month may be specified as a number (1-12), as a month name or...
chrt
chrt sets or retrieves the real-time scheduling attributes of an existing pid, or runs command with the given attributes.
col
col filters out reverse (and half-reverse) line feeds so the output is in the correct order, with only forward and half-forward line feeds. It also replaces any...
colcrt
colcrt provides virtual half-line and reverse line feed sequences for terminals without such capability, and on which overstriking is destructive. Half-line...
colrm
colrm removes selected columns from a file. Input is taken from standard input. Output is sent to standard output. If called with one parameter the columns of...
column
The column utility formats its input into multiple columns. By default, rows are filled before columns. Input is taken from file, or otherwise from standard...
dmesg
dmesg is used to examine or control the kernel ring buffer. The default action is to display all messages from the kernel ring buffer.
eject
eject allows removable media (typically a CD-ROM, floppy disk, tape, JAZ, ZIP or USB disk) to be ejected under software control. The command can also control...
fallocate
fallocate is used to manipulate the allocated disk space for a file, either to deallocate or preallocate it. For filesystems which support the fallocate system...
flock
This utility manages flock(2) locks from within shell scripts or from the command line. The first and second of the above forms wrap the lock around the...
getopt
getopt is used to break up (parse) options in command lines for easy parsing by shell procedures, and to check for legal options. It uses the GNU getopt(3)...
hexdump
The hexdump utility is a filter which displays the specified files, or standard input if no files are specified, in a user-specified format.
ionice
This program sets or gets the I/O scheduling class and priority for a program. If no arguments or just -p is given, ionice will query the current I/O scheduling...
ipcmk
ipcmk allows you to create shared memory segments, message queues, and semaphore arrays.
ipcrm
ipcrm removes System V inter-process communication (IPC) objects and associated data structures from the system. In order to delete such objects, you must be...
ipcs
ipcs shows information on the inter-process communication facilities for which the calling process has read access. By default it shows information about all...
kill
The command kill sends the specified signal to the specified processes or process groups. If no signal is specified, the TERM signal is sent. This TERM signal...
last
last searches back through the /var/log/wtmp file (or the file designated by the -f option) and displays a list of all users logged in (and out) since that file...
logger
logger makes entries in the system log. When the optional message argument is present, it is written to the log. If it is not present, and the -f option is not...
login
login is used when signing onto a system. If no argument is given, login prompts for the username. The user is then prompted for a password, where appropriate...
look
The look utility displays any lines in file which contain string. As look performs a binary search, the lines in file must be sorted (where sort(1) was given...
lscpu
lscpu gathers CPU architecture information from sysfs, /proc/cpuinfo and any applicable architecture-specific libraries (e.g. librtas on Powerpc). The command...
lsipc
lsipc shows information on the inter-process communication facilities for which the calling process has read access.
lslogins
Examine the wtmp and btmp logs, /etc/shadow (if necessary) and /etc/passwd and output the desired data. The default action is to list info about all the users...
mcookie
mcookie generates a 128-bit random hexadecimal number for use with the X authority system.
mesg
The mesg utility is invoked by a user to control write access others have to the terminal device associated with standard error output. If write access is...
more
more is a filter for paging through text one screenful at a time. This version is especially primitive. Users should realize that less(1) provides more(1)...
mountpoint
mountpoint checks whether the given directory or file is mentioned in the /proc/self/mountinfo file.
namei
namei interprets its arguments as pathnames to any type of Unix file (symlinks, files, directories, and so forth). namei then follows each pathname until an...
nsenter
Enters the namespaces of one or more other processes and then executes the specified program.
prlimit
Given a process id and one or more resources, prlimit tries to retrieve and/or modify the limits. When command is given, prlimit will run this command with the...
rename
rename will rename the specified files by replacing the first occurrence of expression in their name by replacement.
renice
renice alters the scheduling priority of one or more running processes. The first argument is the priority value to be used. The other arguments are interpreted...
rev
The rev utility copies the specified files to standard output, reversing the order of characters in every line. If no files are specified, standard input is...
runuser
runuser allows to run commands with a substitute user and group ID. If the option -u is not given, it falls back to su-compatible semantics and a shell is...
script
script makes a typescript of everything displayed on your terminal. It is useful for students who need a hardcopy record of an interactive session as proof of...
scriptreplay
This program replays a typescript, using timing information to ensure that output happens in the same rhythm as it originally appeared when the script was...
setpriv
Sets or queries various Linux privilege settings that are inherited across execve(2). The difference between the commands setpriv and su (or runuser) is that...
setsid
setsid runs a program in a new session.
setterm
setterm writes to standard output a character string that will invoke the specified terminal capabilities. Where possible terminfo is consulted to find the...
su
su allows to run commands with a substitute user and group ID. When called without arguments, su defaults to running an interactive shell as root. For backward...
tailf
tailf is deprecated. It may have unfixed bugs and will be removed from util-linux in March 2017. Nowadays it's safe to use tail -f (from coreutils), in contrast...
taskset
taskset is used to set or retrieve the CPU affinity of a running process given its pid, or to launch a new command with a given CPU affinity. CPU affinity is a...
ul
ul reads the named files (or standard input if none are given) and translates occurrences of underscores to the sequence which indicates underlining for the...
unshare
Unshares the indicated namespaces from the parent process and then executes the specified program. The namespaces can optionally be made persistent by bind...
utmpdump
utmpdump is a simple program to dump UTMP and WTMP files in raw format, so they can be examined. utmpdump reads from stdin unless a filename is passed.
uuidgen
The uuidgen program creates (and prints) a new universally unique identifier (UUID) using the libuuid(3) library. The new UUID can reasonably be considered...
wall
wall displays a message, or the contents of a file, or otherwise its standard input, on the terminals of all currently logged in users. The command will wrap...
whereis
whereis locates the binary, source and manual files for the specified command names. The supplied names are first stripped of leading pathname components and...
write
write allows you to communicate with other users, by copying lines from your terminal to theirs.
File Formats (Section 5)
fstab
The file fstab contains descriptive information about the filesystems the system can mount. fstab is only read by programs, and not written; it is the duty of...
terminal-colors.d
Files in this directory determine the default behavior for utilities when coloring output. The name is a utility name. The name is optional and when none is...
System Administration (Section 8)
addpart
addpart tells the Linux kernel about the existence of the specified partition. The command is a simple wrapper around the "add partition" ioctl. This command...
agetty
agetty opens a tty port, prompts for a login name and invokes the /bin/login command. It is normally invoked by init(8).
blkdiscard
blkdiscard is used to discard device sectors. This is useful for solid-state drivers (SSDs) and thinly-provisioned storage. Unlike fstrim(8), this command is...
blkid
The blkid program is the command-line interface to working with the libblkid(3) library. It can determine the type of content (e.g. filesystem or swap) that a...
blockdev
The utility blockdev allows one to call block device ioctls from the command line.
cfdisk
cfdisk is a curses-based program for partitioning any block device. The default device is /dev/sda. Note that cfdisk provides basic partitioning functionality...
chcpu
chcpu can modify the state of CPUs. It can enable or disable CPUs, scan for new CPUs, change the CPU dispatching mode of the underlying hypervisor, and request...
ctrlaltdel
Based on examination of the linux/kernel/reboot.c code, it is clear that there are two supported functions that the Ctrl-Alt-Del sequence can perform.
delpart
delpart asks the Linux kernel to forget about the specified partition (a number) on the specified device. The command is a simple wrapper around the "del...
fdformat
fdformat does a low-level format on a floppy disk.
fdisk
fdisk is a dialog-driven program for creation and manipulation of partition tables. It understands GPT, MBR, Sun, SGI and BSD partition tables. Block devices...
findfs
findfs will search the block devices in the system looking for a filesystem or partition with specified tag.
findmnt
findmnt will list all mounted filesystems or search for a filesystem. The findmnt command is able to search in /etc/fstab, /etc/mtab or /proc/self/mountinfo. If...
fsck
fsck is used to check and optionally repair one or more Linux filesystems. filesys can be a device name (e.g. /dev/hdc1, /dev/sdb2), a mount point (e.g. /...
fsck.cramfs
fsck.cramfs is used to check the cramfs file system.
fsck.minix
fsck.minix performs a consistency check for the Linux MINIX filesystem. The program assumes the filesystem is quiescent. fsck.minix should not be used on a...
fsfreeze
fsfreeze suspends or resumes access to a filesystem. fsfreeze halts any new access to the filesystem and creates a stable image on disk. fsfreeze is intended to...
fstrim
fstrim is used on a mounted filesystem to discard (or "trim") blocks which are not in use by the filesystem. This is useful for solid-state drives (SSDs) and...
hwclock
hwclock is a tool for accessing the Hardware Clock. It can: display the Hardware Clock time; set the Hardware Clock to a specified time; set the Hardware Clock...
isosize
This command outputs the length of an iso9660 filesystem that is contained in the specified file. This file may be a normal file or a block device (e.g...
ldattach
The ldattach daemon opens the specified device file (which should refer to a serial device) and attaches the line discipline ldisc to it for processing of the...
losetup
losetup is used to associate loop devices with regular files or block devices, to detach loop devices, and to query the status of a loop device. If only the...
lsblk
lsblk lists information about all available or the specified block devices. The lsblk command reads the sysfs filesystem and udev db to gather information. The...
lslocks
lslocks lists information about all the currently held file locks in a Linux system.
lsns
lsns lists information about all the currently accessible namespaces or about the given namespace. The namespace identifier is an inode number. The default...
mkfs
This mkfs frontend is deprecated in favour of filesystem specific mkfs.<type> utils. mkfs is used to build a Linux filesystem on a device, usually a hard disk...
mkfs.cramfs
Files on cramfs file systems are zlib-compressed one page at a time to allow random read access. The metadata is not compressed, but is expressed in a terse...
mkfs.minix
mkfs.minix creates a Linux MINIX filesystem on a device (usually a disk partition).
mkswap
mkswap sets up a Linux swap area on a device or in a file. The device argument will usually be a disk partition (something like /dev/sdb7) but can also be a...
mount
All files accessible in a Unix system are arranged in one big tree, the file hierarchy, rooted at /. These files can be spread out over several devices. The...
nologin
nologin displays a message that an account is not available and exits non-zero. It is intended as a replacement shell field to deny login access to an account...
partx
Given a device or disk-image, partx tries to parse the partition table and list its contents. It can also tell the kernel to add or remove partitions from its...
pivot_root
pivot_root moves the root file system of the current process to the directory put_old and makes new_root the new root file system. Since pivot_root(8) simply...
raw
raw is used to bind a Linux raw character device to a block device. Any block device may be used: at the time of binding, the device driver does not even have...
readprofile
The readprofile command uses the /proc/profile information to print ascii data on standard output. The output is organized in three columns: the first is the...
resizepart
resizepart tells the Linux kernel about the new size of the specified partition. The command is a simple wrapper around the "resize partition" ioctl. This...
rtcwake
This program is used to enter a system sleep state and to automatically wake from it at a specified time. This uses cross-platform Linux interfaces to enter a...
setarch
setarch currently only affects the output of uname -m. For example, on an AMD64 system, running setarch i386 program will cause program to see i686 instead of...
sfdisk
sfdisk is a script-oriented tool for partitioning any block device. Since version 2.26 sfdisk supports MBR (DOS), GPT, SUN and SGI disk labels, but no longer...
sulogin
sulogin is invoked by init when the system goes into single-user mode. The user is prompted:Give root password for system maintenance (or type Control-D for...
swaplabel
swaplabel will display or change the label or UUID of a swap partition located on device (or regular file). If the optional arguments -L and -U are not given...
swapon
swapon is used to specify devices on which paging and swapping are to take place. The device or file used is given by the specialfile parameter. It may be of...
switch_root
switch_root moves already mounted /proc, /dev, /sys and /run to newroot and makes newroot the new root filesystem and starts init process. WARNING: switch_root...
umount
The umount command detaches the mentioned file system(s) from the file hierarchy. A file system is specified by giving the directory where it has been mounted...
wdctl
Show hardware watchdog status. The default device is /dev/watchdog. If more than one device is specified then the output is separated by one blank line. Note...
wipefs
wipefs can erase filesystem, raid or partition-table signatures (magic strings) from the specified device to make the signatures invisible for libblkid. wipefs...
zramctl
zramctl is used to quickly set up zram device parameters, to reset zram devices, and to query the status of used zram devices. If no option is given, all zram...