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BusyBox - The Swiss Army Knife of Embedded Linux


busybox <applet> [arguments...] # or

<applet> [arguments...] # if symlinked


BusyBox combines tiny versions of many common UNIX utilities into a single small
executable. It provides minimalist replacements for most of the utilities you usually find
in GNU coreutils, util-linux, etc. The utilities in BusyBox generally have fewer options
than their full-featured GNU cousins; however, the options that are included provide the
expected functionality and behave very much like their GNU counterparts.

BusyBox has been written with size-optimization and limited resources in mind. It is also
extremely modular so you can easily include or exclude commands (or features) at compile
time. This makes it easy to customize your embedded systems. To create a working system,
just add /dev, /etc, and a Linux kernel. BusyBox provides a fairly complete POSIX
environment for any small or embedded system.

BusyBox is extremely configurable. This allows you to include only the components you
need, thereby reducing binary size. Run 'make config' or 'make menuconfig' to select the
functionality that you wish to enable. Then run 'make' to compile BusyBox using your

After the compile has finished, you should use 'make install' to install BusyBox. This
will install the 'bin/busybox' binary, in the target directory specified by CONFIG_PREFIX.
CONFIG_PREFIX can be set when configuring BusyBox, or you can specify an alternative
location at install time (i.e., with a command line like 'make CONFIG_PREFIX=/tmp/foo
install'). If you enabled any applet installation scheme (either as symlinks or
hardlinks), these will also be installed in the location pointed to by CONFIG_PREFIX.


BusyBox is a multi-call binary. A multi-call binary is an executable program that
performs the same job as more than one utility program. That means there is just a single
BusyBox binary, but that single binary acts like a large number of utilities. This allows
BusyBox to be smaller since all the built-in utility programs (we call them applets) can
share code for many common operations.

You can also invoke BusyBox by issuing a command as an argument on the command line. For
example, entering

/bin/busybox ls

will also cause BusyBox to behave as 'ls'.

Of course, adding '/bin/busybox' into every command would be painful. So most people will
invoke BusyBox using links to the BusyBox binary.

For example, entering

ln -s /bin/busybox ls

will cause BusyBox to behave as 'ls' (if the 'ls' command has been compiled into BusyBox).
Generally speaking, you should never need to make all these links yourself, as the BusyBox
build system will do this for you when you run the 'make install' command.

If you invoke BusyBox with no arguments, it will provide you with a list of the applets
that have been compiled into your BusyBox binary.


Most BusyBox applets support the --help argument to provide a terse runtime description of
their behavior. If the CONFIG_FEATURE_VERBOSE_USAGE option has been enabled, more
detailed usage information will also be available.


Currently available applets include:

[, [[, acpid, adjtimex, ar, arp, arping, ash, awk, basename,
blockdev, brctl, bunzip2, bzcat, bzip2, cal, cat, chgrp, chmod,
chown, chpasswd, chroot, chvt, clear, cmp, cp, cpio, crond, crontab,
cttyhack, cut, date, dc, dd, deallocvt, depmod, devmem, df, diff,
dirname, dmesg, dnsdomainname, dos2unix, dpkg, dpkg-deb, du,
dumpkmap, dumpleases, echo, ed, egrep, env, expand, expr, false,
fdisk, fgrep, find, fold, free, freeramdisk, fstrim, ftpget, ftpput,
getopt, getty, grep, groups, gunzip, gzip, halt, head, hexdump,
hostid, hostname, httpd, hwclock, id, ifconfig, ifdown, ifup, init,
insmod, ionice, ip, ipcalc, kill, killall, klogd, last, less, ln,
loadfont, loadkmap, logger, login, logname, logread, losetup, ls,
lsmod, lzcat, lzma, lzop, lzopcat, md5sum, mdev, microcom, mkdir,
mkfifo, mknod, mkswap, mktemp, modinfo, modprobe, more, mount, mt,
mv, nameif, nc, netstat, nslookup, od, openvt, passwd, patch, pidof,
ping, ping6, pivot_root, poweroff, printf, ps, pwd, rdate, readlink,
realpath, reboot, renice, reset, rev, rm, rmdir, rmmod, route, rpm,
rpm2cpio, run-parts, sed, seq, setkeycodes, setsid, sh, sha1sum,
sha256sum, sha512sum, sleep, sort, start-stop-daemon, stat,
static-sh, strings, stty, su, sulogin, swapoff, swapon, switch_root,
sync, sysctl, syslogd, tac, tail, tar, taskset, tee, telnet,
telnetd, test, tftp, time, timeout, top, touch, tr, traceroute,
traceroute6, true, tty, tunctl, udhcpc, udhcpd, umount, uname,
uncompress, unexpand, uniq, unix2dos, unlzma, unlzop, unxz, unzip,
uptime, usleep, uudecode, uuencode, vconfig, vi, watch, watchdog,
wc, wget, which, who, whoami, xargs, xz, xzcat, yes, zcat


acpid [-df] [-c CONFDIR] [-l LOGFILE] [-a ACTIONFILE] [-M MAPFILE] [-e

Listen to ACPI events and spawn specific helpers on event arrival

-d Log to stderr, not log file (implies -f)
-f Run in foreground
-c DIR Config directory [/etc/acpi]
-e FILE /proc event file [/proc/acpi/event]
-l FILE Log file [/var/log/acpid.log]
-p FILE Pid file [/var/run/acpid.pid]
-a FILE Action file [/etc/acpid.conf]
-M FILE Map file [/etc/acpi.map]

Accept and ignore compatibility options -g -m -s -S -v

adjtimex [-q] [-o OFF] [-f FREQ] [-p TCONST] [-t TICK]

Read and optionally set system timebase parameters. See adjtimex(2)

-q Quiet
-o OFF Time offset, microseconds
-f FREQ Frequency adjust, integer kernel units (65536 is 1ppm)
(positive values make clock run faster)
-t TICK Microseconds per tick, usually 10000

ar ar [-o] [-v] [-p] [-t] [-x] ARCHIVE FILES

Extract or list FILES from an ar archive

-o Preserve original dates
-p Extract to stdout
-t List
-x Extract
-v Verbose

arp arp [-vn] [-H HWTYPE] [-i IF] -a [HOSTNAME] [-v] [-i IF] -d HOSTNAME
[pub] [-v] [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [temp] [-v] [-H HWTYPE] [-i IF] -s
[netmask MASK] pub

Manipulate ARP cache

-a Display (all) hosts
-d Delete ARP entry
-s Set new entry
-v Verbose
-n Don't resolve names
-i IF Network interface
-A,-p AF Protocol family
-H HWTYPE Hardware address type

arping [-fqbDUA] [-c CNT] [-w TIMEOUT] [-I IFACE] [-s SRC_IP] DST_IP

Send ARP requests/replies

-f Quit on first ARP reply
-q Quiet
-b Keep broadcasting, don't go unicast
-D Duplicated address detection mode
-U Unsolicited ARP mode, update your neighbors
-A ARP answer mode, update your neighbors
-c N Stop after sending N ARP requests
-w TIMEOUT Time to wait for ARP reply, seconds
-I IFACE Interface to use (default eth0)
-s SRC_IP Sender IP address
DST_IP Target IP address

ash ash [-/+OPTIONS] [-/+o OPT]... [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]

Unix shell interpreter


-v VAR=VAL Set variable
-F SEP Use SEP as field separator
-f FILE Read program from FILE

basename FILE [SUFFIX]

Strip directory path and .SUFFIX from FILE


--setro Set ro
--setrw Set rw
--getro Get ro
--getss Get sector size
--getbsz Get block size
--setbsz BYTES Set block size
--getsz Get device size in 512-byte sectors
--getsize64 Get device size in bytes
--flushbufs Flush buffers
--rereadpt Reread partition table


Manage ethernet bridges


addbr BRIDGE Create BRIDGE
delbr BRIDGE Delete BRIDGE

bunzip2 [-cf] [FILE]...

Decompress FILEs (or stdin)

-c Write to stdout
-f Force

bzcat [FILE]...

Decompress to stdout

bzip2 [OPTIONS] [FILE]...

Compress FILEs (or stdin) with bzip2 algorithm

-1..9 Compression level
-d Decompress
-c Write to stdout
-f Force

cal cal [-jy] [[MONTH] YEAR]

Display a calendar

-j Use julian dates
-y Display the entire year

cat cat [FILE]...

Concatenate FILEs and print them to stdout

chgrp [-RhLHPcvf]... GROUP FILE...

Change the group membership of each FILE to GROUP

-R Recurse
-h Affect symlinks instead of symlink targets
-L Traverse all symlinks to directories
-H Traverse symlinks on command line only
-P Don't traverse symlinks (default)
-c List changed files
-v Verbose
-f Hide errors

chmod [-Rcvf] MODE[,MODE]... FILE...

Each MODE is one or more of the letters ugoa, one of the symbols +-= and one or more
of the letters rwxst

-R Recurse
-c List changed files
-v List all files
-f Hide errors

chown [-RhLHPcvf]... OWNER[<.|:>[GROUP]] FILE...

Change the owner and/or group of each FILE to OWNER and/or GROUP

-R Recurse
-h Affect symlinks instead of symlink targets
-L Traverse all symlinks to directories
-H Traverse symlinks on command line only
-P Don't traverse symlinks (default)
-c List changed files
-v List all files
-f Hide errors

chpasswd [--md5|--encrypted]

Read user:password from stdin and update /etc/passwd

-e,--encrypted Supplied passwords are in encrypted form
-m,--md5 Use MD5 encryption instead of DES


Run PROG with root directory set to NEWROOT

chvt N

Change the foreground virtual terminal to /dev/ttyN


Clear screen

cmp cmp [-l] [-s] FILE1 [FILE2 [SKIP1 [SKIP2]]]

Compare FILE1 with FILE2 (or stdin)

-l Write the byte numbers (decimal) and values (octal)
for all differing bytes
-s Quiet


Copy SOURCE(s) to DEST

-a Same as -dpR
-R,-r Recurse
-d,-P Preserve symlinks (default if -R)
-L Follow all symlinks
-H Follow symlinks on command line
-p Preserve file attributes if possible
-f Overwrite
-i Prompt before overwrite
-l,-s Create (sym)links

cpio [-dmvu] [-F FILE] [-H newc] [-tio] [EXTR_FILE]...

Extract or list files from a cpio archive, or create an archive using file list on

Main operation mode:

-t List
-i Extract EXTR_FILEs (or all)
-o Create (requires -H newc)
-d Make leading directories
-m Preserve mtime
-v Verbose
-u Overwrite
-F FILE Input (-t,-i,-p) or output (-o) file
-H newc Archive format

crond -fbS -l N -L LOGFILE -c DIR

-f Foreground
-b Background (default)
-S Log to syslog (default)
-l Set log level. 0 is the most verbose, default 8
-L Log to file
-c Working dir

crontab [-c DIR] [-u USER] [-ler]|[FILE]

-c Crontab directory
-u User
-l List crontab
-e Edit crontab
-r Delete crontab
FILE Replace crontab by FILE ('-': stdin)

cttyhack [PROG ARGS]

Give PROG a controlling tty if possible. Example for /etc/inittab (for busybox init):
::respawn:/bin/cttyhack /bin/sh Giving controlling tty to shell running with PID
1: $ exec cttyhack sh Starting interactive shell from boot shell script:

setsid cttyhack sh

cut cut [OPTIONS] [FILE]...

Print selected fields from each input FILE to stdout

-b LIST Output only bytes from LIST
-c LIST Output only characters from LIST
-d CHAR Use CHAR instead of tab as the field delimiter
-s Output only the lines containing delimiter
-f N Print only these fields
-n Ignored

date [OPTIONS] [+FMT] [TIME]

Display time (using +FMT), or set time

[-s,--set] TIME Set time to TIME
-u,--utc Work in UTC (don't convert to local time)
-R,--rfc-2822 Output RFC-2822 compliant date string
-I[SPEC] Output ISO-8601 compliant date string
SPEC='date' (default) for date only,
'hours', 'minutes', or 'seconds' for date and
time to the indicated precision
-r,--reference FILE Display last modification time of FILE
-d,--date TIME Display TIME, not 'now'
-D FMT Use FMT for -d TIME conversion

Recognized TIME formats:

YYYY-MM-DD hh:mm[:ss]
'date TIME' form accepts MMDDhhmm[[YY]YY][.ss] instead


Tiny RPN calculator. Operations: +, add, -, sub, *, mul, /, div, %, mod, and, or, not,
xor, p - print top of the stack (without popping), f - print entire stack, o - pop the
value and set output radix (must be 10, 16, 8 or 2). Examples: 'dc 2 2 add p' -> 4,
'dc 8 8 mul 2 2 + / p' -> 16

dd dd [if=FILE] [of=FILE] [ibs=N] [obs=N] [bs=N] [count=N] [skip=N] [seek=N]

Copy a file with converting and formatting

if=FILE Read from FILE instead of stdin
of=FILE Write to FILE instead of stdout
bs=N Read and write N bytes at a time
ibs=N Read N bytes at a time
obs=N Write N bytes at a time
count=N Copy only N input blocks
skip=N Skip N input blocks
seek=N Skip N output blocks
conv=notrunc Don't truncate output file
conv=noerror Continue after read errors
conv=sync Pad blocks with zeros
conv=fsync Physically write data out before finishing
conv=swab Swap every pair of bytes

N may be suffixed by c (1), w (2), b (512), kD (1000), k (1024), MD, M, GD, G

deallocvt [N]

Deallocate unused virtual terminal /dev/ttyN

depmod [-n] [-b BASE] [VERSION] [MODFILES]...

Generate modules.dep, alias, and symbols files

-b BASE Use BASE/lib/modules/VERSION
-n Dry run: print files to stdout


Read/write from physical address

ADDRESS Address to act upon
WIDTH Width (8/16/...)
VALUE Data to be written

df df [-Pkmhai] [-B SIZE] [FILESYSTEM]...

Print filesystem usage statistics

-P POSIX output format
-k 1024-byte blocks (default)
-m 1M-byte blocks
-h Human readable (e.g. 1K 243M 2G)
-a Show all filesystems
-i Inodes
-B SIZE Blocksize

diff [-abBdiNqrTstw] [-L LABEL] [-S FILE] [-U LINES] FILE1 FILE2

Compare files line by line and output the differences between them. This
implementation supports unified diffs only.

-a Treat all files as text
-b Ignore changes in the amount of whitespace
-B Ignore changes whose lines are all blank
-d Try hard to find a smaller set of changes
-i Ignore case differences
-L Use LABEL instead of the filename in the unified header
-N Treat absent files as empty
-q Output only whether files differ
-r Recurse
-S Start with FILE when comparing directories
-T Make tabs line up by prefixing a tab when necessary
-s Report when two files are the same
-t Expand tabs to spaces in output
-U Output LINES lines of context
-w Ignore all whitespace

dirname FILENAME

Strip non-directory suffix from FILENAME

dmesg [-c] [-n LEVEL] [-s SIZE]

Print or control the kernel ring buffer

-c Clear ring buffer after printing
-n LEVEL Set console logging level
-s SIZE Buffer size

dos2unix [-ud] [FILE]

Convert FILE in-place from DOS to Unix format. When no file is given, use

-u dos2unix
-d unix2dos

dpkg [-ilCPru] [-F OPT] PACKAGE

Install, remove and manage Debian packages

-i,--install Install the package
-l,--list List of installed packages
--configure Configure an unpackaged package
-P,--purge Purge all files of a package
-r,--remove Remove all but the configuration files for a package
--unpack Unpack a package, but don't configure it
--force-depends Ignore dependency problems
--force-confnew Overwrite existing config files when installing
--force-confold Keep old config files when installing

dpkg-deb [-cefxX] FILE [argument]

Perform actions on Debian packages (.debs)

-c List contents of filesystem tree
-e Extract control files to [argument] directory
-f Display control field name starting with [argument]
-x Extract packages filesystem tree to directory
-X Verbose extract

du du [-aHLdclsxhmk] [FILE]...

Summarize disk space used for each FILE and/or directory

-a Show file sizes too
-L Follow all symlinks
-H Follow symlinks on command line
-d N Limit output to directories (and files with -a) of depth < N
-c Show grand total
-l Count sizes many times if hard linked
-s Display only a total for each argument
-x Skip directories on different filesystems
-h Sizes in human readable format (e.g., 1K 243M 2G)
-m Sizes in megabytes
-k Sizes in kilobytes (default)

dumpkmap > keymap

Print a binary keyboard translation table to stdout

dumpleases [-r|-a] [-f LEASEFILE]

Display DHCP leases granted by udhcpd

-f,--file=FILE Lease file
-r,--remaining Show remaining time
-a,--absolute Show expiration time

echo [-neE] [ARG]...

Print the specified ARGs to stdout

-n Suppress trailing newline
-e Interpret backslash escapes (i.e., \t=tab)
-E Don't interpret backslash escapes (default)

ed ed

env env [-iu] [-] [name=value]... [PROG ARGS]

Print the current environment or run PROG after setting up the specified environment

-, -i Start with an empty environment
-u Remove variable from the environment

expand [-i] [-t N] [FILE]...

Convert tabs to spaces, writing to stdout

-i,--initial Don't convert tabs after non blanks
-t,--tabs=N Tabstops every N chars


Print the value of EXPRESSION to stdout


ARG1 | ARG2 ARG1 if it is neither null nor 0, otherwise ARG2
ARG1 & ARG2 ARG1 if neither argument is null or 0, otherwise 0
ARG1 < ARG2 1 if ARG1 is less than ARG2, else 0. Similarly:
ARG1 <= ARG2
ARG1 != ARG2
ARG1 >= ARG2
ARG1 + ARG2 Sum of ARG1 and ARG2. Similarly:
STRING : REGEXP Anchored pattern match of REGEXP in STRING
substr STRING POS LENGTH Substring of STRING, POS counted from 1
index STRING CHARS Index in STRING where any CHARS is found, or 0
length STRING Length of STRING
quote TOKEN Interpret TOKEN as a string, even if
it is a keyword like 'match' or an
operator like '/'

Beware that many operators need to be escaped or quoted for shells. Comparisons are
arithmetic if both ARGs are numbers, else lexicographical. Pattern matches return the
string matched between \( and \) or null; if \( and \) are not used, they return the
number of characters matched or 0.


Return an exit code of FALSE \fIs0(1)

fdisk [-ul] [-C CYLINDERS] [-H HEADS] [-S SECTORS] [-b SSZ] DISK

Change partition table

-u Start and End are in sectors (instead of cylinders)
-l Show partition table for each DISK, then exit
-b 2048 (for certain MO disks) use 2048-byte sectors
-C CYLINDERS Set number of cylinders/heads/sectors

find [-HL] [PATH]... [OPTIONS] [ACTIONS]

Search for files and perform actions on them. First failed action stops processing of
current file. Defaults: PATH is current directory, action is '-print'

-L,-follow Follow symlinks
-H ...on command line only
-xdev Don't descend directories on other filesystems
-maxdepth N Descend at most N levels. -maxdepth 0 applies
actions to command line arguments only
-mindepth N Don't act on first N levels
-depth Act on directory *after* traversing it


( ACTIONS ) Group actions for -o / -a
! ACT Invert ACT's success/failure
ACT1 [-a] ACT2 If ACT1 fails, stop, else do ACT2
ACT1 -o ACT2 If ACT1 succeeds, stop, else do ACT2
Note: -a has higher priority than -o
-name PATTERN Match file name (w/o directory name) to PATTERN
-iname PATTERN Case insensitive -name
-path PATTERN Match path to PATTERN
-ipath PATTERN Case insensitive -path
-regex PATTERN Match path to regex PATTERN
-type X File type is X (one of: f,d,l,b,c,...)
-perm MASK At least one mask bit (+MASK), all bits (-MASK),
or exactly MASK bits are set in file's mode
-mtime DAYS mtime is greater than (+N), less than (-N),
or exactly N days in the past
-mmin MINS mtime is greater than (+N), less than (-N),
or exactly N minutes in the past
-newer FILE mtime is more recent than FILE's
-inum N File has inode number N
-user NAME/ID File is owned by given user
-group NAME/ID File is owned by given group
-size N[bck] File size is N (c:bytes,k:kbytes,b:512 bytes(def.))
+/-N: file size is bigger/smaller than N
-links N Number of links is greater than (+N), less than (-N),
or exactly N
-prune If current file is directory, don't descend into it
If none of the following actions is specified, -print is assumed
-print Print file name
-print0 Print file name, NUL terminated
-exec CMD ARG ; Run CMD with all instances of {} replaced by
file name. Fails if CMD exits with nonzero

fold [-bs] [-w WIDTH] [FILE]...

Wrap input lines in each FILE (or stdin), writing to stdout

-b Count bytes rather than columns
-s Break at spaces
-w Use WIDTH columns instead of 80

free [-b/k/m/g]

Display the amount of free and used system memory

freeramdisk DEVICE

Free all memory used by the specified ramdisk


-o,--offset=OFFSET Offset in bytes to discard from
-l,--length=LEN Bytes to discard
-m,--minimum=MIN Minimum extent length
-v,--verbose Print number of discarded bytes


Download a file via FTP

-c,--continue Continue previous transfer
-v,--verbose Verbose
-u,--username USER Username
-p,--password PASS Password
-P,--port NUM Port


Upload a file to a FTP server

-v,--verbose Verbose
-u,--username USER Username
-p,--password PASS Password
-P,--port NUM Port


-a,--alternative Allow long options starting with single -
-l,--longoptions=LOPT[,...] Long options to recognize
-n,--name=PROGNAME The name under which errors are reported
-o,--options=OPTSTRING Short options to recognize
-q,--quiet No error messages on unrecognized options
-Q,--quiet-output No normal output
-s,--shell=SHELL Set shell quoting conventions
-T,--test Version test (exits with 4)
-u,--unquoted Don't quote output


O=`getopt -l bb: -- ab:c:: "$@"` || exit 1 eval set -- "$O" while true; do case
"$1" in -a) echo A; shift;; -b|--bb) echo "B:'$2'"; shift 2;;
-c) case "$2" in "") echo C; shift 2;; *) echo "C:'$2'";
shift 2;; esac;; --) shift; break;; *) echo Error; exit 1;;
esac done


Open TTY, prompt for login name, then invoke /bin/login

-h Enable hardware RTS/CTS flow control
-L Set CLOCAL (ignore Carrier Detect state)
-m Get baud rate from modem's CONNECT status message
-n Don't prompt for login name
-w Wait for CR or LF before sending /etc/issue
-i Don't display /etc/issue
-f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue
-l LOGIN Invoke LOGIN instead of /bin/login
-t SEC Terminate after SEC if no login name is read
-I INITSTR Send INITSTR before anything else
-H HOST Log HOST into the utmp file as the hostname

BAUD_RATE of 0 leaves it unchanged

grep [-HhnlLoqvsriwFEz] [-m N] [-A/B/C N] PATTERN/-e PATTERN.../-f FILE [FILE]...

Search for PATTERN in FILEs (or stdin)

-H Add 'filename:' prefix
-h Do not add 'filename:' prefix
-n Add 'line_no:' prefix
-l Show only names of files that match
-L Show only names of files that don't match
-c Show only count of matching lines
-o Show only the matching part of line
-q Quiet. Return 0 if PATTERN is found, 1 otherwise
-v Select non-matching lines
-s Suppress open and read errors
-r Recurse
-i Ignore case
-w Match whole words only
-x Match whole lines only
-F PATTERN is a literal (not regexp)
-E PATTERN is an extended regexp
-z Input is NUL terminated
-m N Match up to N times per file
-A N Print N lines of trailing context
-B N Print N lines of leading context
-C N Same as '-A N -B N'
-e PTRN Pattern to match
-f FILE Read pattern from file

groups [USER]

Print the group memberships of USER or for the current process

gunzip [-cft] [FILE]...

Decompress FILEs (or stdin)

-c Write to stdout
-f Force
-t Test file integrity

gzip [-cfd] [FILE]...

Compress FILEs (or stdin)

-d Decompress
-c Write to stdout
-f Force

halt [-d DELAY] [-n] [-f] [-w]

Halt the system

-d SEC Delay interval
-n Do not sync
-f Force (don't go through init)
-w Only write a wtmp record

head [OPTIONS] [FILE]...

Print first 10 lines of each FILE (or stdin) to stdout. With more than one FILE,
precede each with a filename header.

-n N[kbm] Print first N lines
-n -N[kbm] Print all except N last lines
-c [-]N[kbm] Print first N bytes
-q Never print headers
-v Always print headers

N may be suffixed by k (x1024), b (x512), or m (x1024^2).

hexdump [-bcCdefnosvx] [FILE]...

Display FILEs (or stdin) in a user specified format

-b One-byte octal display
-c One-byte character display
-C Canonical hex+ASCII, 16 bytes per line
-d Two-byte decimal display
-n LENGTH Interpret only LENGTH bytes of input
-o Two-byte octal display
-s OFFSET Skip OFFSET bytes
-v Display all input data
-x Two-byte hexadecimal display


Print out a unique 32-bit identifier for the machine


Get or set hostname or DNS domain name

-s Short
-i Addresses for the hostname
-d DNS domain name
-f Fully qualified domain name
-F FILE Use FILE's content as hostname

httpd [-ifv[v]] [-c CONFFILE] [-p [IP:]PORT] [-u USER[:GRP]] [-r REALM] [-h HOME] or
httpd -d/-e/-m STRING

Listen for incoming HTTP requests

-i Inetd mode
-f Don't daemonize
-v[v] Verbose
-p [IP:]PORT Bind to IP:PORT (default *:80)
-u USER[:GRP] Set uid/gid after binding to port
-r REALM Authentication Realm for Basic Authentication
-h HOME Home directory (default .)
-c FILE Configuration file (default {/etc,HOME}/httpd.conf)

hwclock [-r|--show] [-s|--hctosys] [-w|--systohc] [-t|--systz] [-l|--localtime]
[-u|--utc] [-f|--rtc FILE]

Query and set hardware clock (RTC)

-r Show hardware clock time
-s Set system time from hardware clock
-w Set hardware clock from system time
-t Set in-kernel timezone, correct system time
if hardware clock is in local time
-u Assume hardware clock is kept in UTC
-l Assume hardware clock is kept in local time
-f FILE Use specified device (e.g. /dev/rtc2)

id id [OPTIONS] [USER]

Print information about USER or the current user

-u User ID
-g Group ID
-G Supplementary group IDs
-n Print names instead of numbers
-r Print real ID instead of effective ID

ifconfig [-a] interface [address]

Configure a network interface

[[-]broadcast [ADDRESS]] [[-]pointopoint [ADDRESS]]
[netmask ADDRESS] [dstaddr ADDRESS]
[outfill NN] [keepalive NN]
[hw ether|infiniband ADDRESS] [metric NN] [mtu NN]
[[-]trailers] [[-]arp] [[-]allmulti]
[multicast] [[-]promisc] [txqueuelen NN] [[-]dynamic]
[mem_start NN] [io_addr NN] [irq NN]
[up|down] ...

ifdown [-anmvf] [-i FILE] IFACE...

-a De/configure all interfaces automatically
-i FILE Use FILE for interface definitions
-n Print out what would happen, but don't do it
(note: doesn't disable mappings)
-m Don't run any mappings
-v Print out what would happen before doing it
-f Force de/configuration

ifup [-anmvf] [-i FILE] IFACE...

-a De/configure all interfaces automatically
-i FILE Use FILE for interface definitions
-n Print out what would happen, but don't do it
(note: doesn't disable mappings)
-m Don't run any mappings
-v Print out what would happen before doing it
-f Force de/configuration


Init is the first process started during boot. It never exits. It (re)spawns children
according to /etc/inittab.


Load the specified kernel modules into the kernel

ionice [-c 1-3] [-n 0-7] [-p PID] [PROG]

Change I/O priority and class

-c Class. 1:realtime 2:best-effort 3:idle
-n Priority

ip ip [OPTIONS] {address | route | link | tunnel | rule} {COMMAND}

ip [OPTIONS] OBJECT {COMMAND} where OBJECT := {address | route | link | tunnel | rule}
OPTIONS := { -f[amily] { inet | inet6 | link } | -o[neline] }


Calculate IP network settings from a IP address

-b,--broadcast Display calculated broadcast address
-n,--network Display calculated network address
-m,--netmask Display default netmask for IP
-p,--prefix Display the prefix for IP/NETMASK
-h,--hostname Display first resolved host name
-s,--silent Don't ever display error messages

kill [-l] [-SIG] PID...

Send a signal (default: TERM) to given PIDs

-l List all signal names and numbers

killall [-l] [-q] [-SIG] PROCESS_NAME...

Send a signal (default: TERM) to given processes

-l List all signal names and numbers
-q Don't complain if no processes were killed

klogd [-c N] [-n]

Kernel logger

-c N Print to console messages more urgent than prio N (1-8)
-n Run in foreground


Show listing of the last users that logged into the system

less [-EMmNh~I?] [FILE]...

View FILE (or stdin) one screenful at a time

-E Quit once the end of a file is reached
-M,-m Display status line with line numbers
and percentage through the file
-N Prefix line number to each line
-I Ignore case in all searches
-~ Suppress ~s displayed past EOF


Create a link LINK or DIR/TARGET to the specified TARGET(s)

-s Make symlinks instead of hardlinks
-f Remove existing destinations
-n Don't dereference symlinks - treat like normal file
-b Make a backup of the target (if exists) before link operation
-S suf Use suffix instead of ~ when making backup files
-T 2nd arg must be a DIR
-v Verbose

loadfont < font

Load a console font from stdin

loadkmap < keymap

Load a binary keyboard translation table from stdin


Write MESSAGE (or stdin) to syslog

-s Log to stderr as well as the system log
-t TAG Log using the specified tag (defaults to user name)
-p PRIO Priority (numeric or facility.level pair)

login [-p] [-h HOST] [[-f] USER]

Begin a new session on the system

-f Don't authenticate (user already authenticated)
-h Name of the remote host
-p Preserve environment


Print the name of the current user

logread [-f]

Show messages in syslogd's circular buffer

-f Output data as log grows

losetup [-r] [-o OFS] {-f|LOOPDEV} FILE - associate loop devices losetup -d
LOOPDEV - disassociate losetup -a - show status losetup -f - show next free
loop device

-o OFS Start OFS bytes into FILE
-r Read-only
-f Show/use next free loop device

ls ls [-1AaCxdLHRFplinsehrSXvctu] [-w WIDTH] [FILE]...

List directory contents

-1 One column output
-a Include entries which start with .
-A Like -a, but exclude . and ..
-C List by columns
-x List by lines
-d List directory entries instead of contents
-L Follow symlinks
-H Follow symlinks on command line
-R Recurse
-p Append / to dir entries
-F Append indicator (one of */=@|) to entries
-l Long listing format
-i List inode numbers
-n List numeric UIDs and GIDs instead of names
-s List allocated blocks
-e List full date and time
-h List sizes in human readable format (1K 243M 2G)
-r Sort in reverse order
-S Sort by size
-X Sort by extension
-v Sort by version
-c With -l: sort by ctime
-t With -l: sort by mtime
-u With -l: sort by atime
-w N Assume the terminal is N columns wide
--color[={always,never,auto}] Control coloring


List the currently loaded kernel modules

lzcat [FILE]...

Decompress to stdout

lzma -d [-cf] [FILE]...

Decompress FILE (or stdin)

-d Decompress
-c Write to stdout
-f Force

lzop [-cfvd123456789CF] [FILE]...

-1..9 Compression level
-d Decompress
-c Write to stdout
-f Force
-v Verbose
-F Don't store or verify checksum
-C Also write checksum of compressed block

lzopcat [-vCF] [FILE]...

-v Verbose
-F Don't store or verify checksum

md5sum [-c[sw]] [FILE]...

Print or check MD5 checksums

-c Check sums against list in FILEs
-s Don't output anything, status code shows success
-w Warn about improperly formatted checksum lines

mdev [-s]

mdev -s is to be run during boot to scan /sys and populate /dev.

Bare mdev is a kernel hotplug helper. To activate it: echo /sbin/mdev

It uses /etc/mdev.conf with lines [-][ENV=regex;]...DEVNAME UID:GID PERM
[>|=PATH]|[!] [@|$|*PROG] where DEVNAME is device name regex, @major,minor[-minor2],
or environment variable regex. A common use of the latter is to load modules for
hotplugged devices:

$MODALIAS=.* 0:0 660 @modprobe "$MODALIAS"

If /dev/mdev.seq file exists, mdev will wait for its value to match $SEQNUM variable.
This prevents plug/unplug races. To activate this feature, create empty /dev/mdev.seq
at boot.

If /dev/mdev.log file exists, debug log will be appended to it.

microcom [-d DELAY] [-t TIMEOUT] [-s SPEED] [-X] TTY

Copy bytes for stdin to TTY and from TTY to stdout

-d Wait up to DELAY ms for TTY output before sending every
next byte to it
-t Exit if both stdin and TTY are silent for TIMEOUT ms
-s Set serial line to SPEED
-X Disable special meaning of NUL and Ctrl-X from stdin



-m MODE Mode
-p No error if exists; make parent directories as needed

mkfifo [-m MODE] NAME

Create named pipe

-m MODE Mode (default a=rw)


Create a special file (block, character, or pipe)

-m MODE Creation mode (default a=rw)
b Block device
c or u Character device
p Named pipe (MAJOR and MINOR are ignored)


Prepare BLOCKDEV to be used as swap partition

-L LBL Label

mktemp [-dt] [-p DIR] [TEMPLATE]

Create a temporary file with name based on TEMPLATE and print its name. TEMPLATE must
end with XXXXXX (e.g. [/dir/]nameXXXXXX). Without TEMPLATE, -t tmp.XXXXXX is assumed.

-d Make directory, not file
-q Fail silently on errors
-t Prepend base directory name to TEMPLATE
-p DIR Use DIR as a base directory (implies -t)
-u Do not create anything; print a name

Base directory is: -p DIR, else $TMPDIR, else /tmp

modinfo [-adlp0] [-F keyword] MODULE

-a Shortcut for '-F author'
-d Shortcut for '-F description'
-l Shortcut for '-F license'
-p Shortcut for '-F parm'
-F keyword Keyword to look for
-0 Separate output with NULs

modprobe [-alrqvsDb] MODULE [symbol=value]...

-a Load multiple MODULEs
-l List (MODULE is a pattern)
-r Remove MODULE (stacks) or do autoclean
-q Quiet
-v Verbose
-s Log to syslog
-D Show dependencies
-b Apply blacklist to module names too

more [FILE]...

View FILE (or stdin) one screenful at a time


Mount a filesystem. Filesystem autodetection requires /proc.

-a Mount all filesystems in fstab
-f Dry run
-i Don't run mount helper
-r Read-only mount
-w Read-write mount (default)
-t FSTYPE[,...] Filesystem type(s)
-O OPT Mount only filesystems with option OPT (-a only)
-o OPT:
loop Ignored (loop devices are autodetected)
[a]sync Writes are [a]synchronous
[no]atime Disable/enable updates to inode access times
[no]diratime Disable/enable atime updates to directories
[no]relatime Disable/enable atime updates relative to modification time
[no]dev (Dis)allow use of special device files
[no]exec (Dis)allow use of executable files
[no]suid (Dis)allow set-user-id-root programs
[r]shared Convert [recursively] to a shared subtree
[r]slave Convert [recursively] to a slave subtree
[r]private Convert [recursively] to a private subtree
[un]bindable Make mount point [un]able to be bind mounted
[r]bind Bind a file or directory [recursively] to another location
move Relocate an existing mount point
remount Remount a mounted filesystem, changing flags
ro/rw Same as -r/-w

There are filesystem-specific -o flags.

mt mt [-f device] opcode value

Control magnetic tape drive operation

Available Opcodes:

bsf bsfm bsr bss datacompression drvbuffer eof eom erase fsf fsfm fsr fss load lock
mkpart nop offline ras1 ras2 ras3 reset retension rewind rewoffline seek setblk
setdensity setpart tell unload unlock weof wset

mv mv [-fin] SOURCE DEST or: mv [-fin] SOURCE... DIRECTORY

Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY

-f Don't prompt before overwriting
-i Interactive, prompt before overwrite
-n Don't overwrite an existing file

nameif [-s] [-c FILE] [IFNAME HWADDR]...

Rename network interface while it in the down state. The device with address HWADDR
is renamed to IFACE.

-c FILE Configuration file (default: /etc/mactab)
-s Log to syslog

nc nc [-iN] [-wN] [-l] [-p PORT] [-f FILE|IPADDR PORT] [-e PROG]

Open a pipe to IP:PORT or FILE

-l Listen mode, for inbound connects
(use -ll with -e for persistent server)
-p PORT Local port
-w SEC Connect timeout
-i SEC Delay interval for lines sent
-f FILE Use file (ala /dev/ttyS0) instead of network
-e PROG Run PROG after connect

netstat [-ral] [-tuwx] [-en]

Display networking information

-r Routing table
-a All sockets
-l Listening sockets
Else: connected sockets
-t TCP sockets
-u UDP sockets
-w Raw sockets
-x Unix sockets
Else: all socket types
-e Other/more information
-n Don't resolve names

nslookup [HOST] [SERVER]

Query the nameserver for the IP address of the given HOST optionally using a specified
DNS server

od od [-abcdfhilovxs] [-t TYPE] [-A RADIX] [-N SIZE] [-j SKIP] [-S MINSTR] [-w WIDTH]

Print FILEs (or stdin) unambiguously, as octal bytes by default

openvt [-c N] [-sw] [PROG ARGS]

Start PROG on a new virtual terminal

-c N Use specified VT
-s Switch to the VT
-w Wait for PROG to exit

passwd [OPTIONS] [USER]

Change USER's password (default: current user)

-a ALG Encryption method
-d Set password to ''
-l Lock (disable) account
-u Unlock (enable) account


-p,--strip N Strip N leading components from file names
-i,--input DIFF Read DIFF instead of stdin
-R,--reverse Reverse patch
-N,--forward Ignore already applied patches
-E,--remove-empty-files Remove output files if they become empty

pidof [NAME]...

List PIDs of all processes with names that match NAMEs


Send ICMP ECHO_REQUEST packets to network hosts

-4,-6 Force IP or IPv6 name resolution
-c CNT Send only CNT pings
-s SIZE Send SIZE data bytes in packets (default:56)
-t TTL Set TTL
-I IFACE/IP Use interface or IP address as source
-W SEC Seconds to wait for the first response (default:10)
(after all -c CNT packets are sent)
-w SEC Seconds until ping exits (default:infinite)
(can exit earlier with -c CNT)
-q Quiet, only displays output at start
and when finished


Send ICMP ECHO_REQUEST packets to network hosts

-c CNT Send only CNT pings
-s SIZE Send SIZE data bytes in packets (default:56)
-I IFACE/IP Use interface or IP address as source
-q Quiet, only displays output at start
and when finished

pivot_root NEW_ROOT PUT_OLD

Move the current root file system to PUT_OLD and make NEW_ROOT the new root file

poweroff [-d DELAY] [-n] [-f]

Halt and shut off power

-d SEC Delay interval
-n Do not sync
-f Force (don't go through init)

printf FORMAT [ARG]...

Format and print ARG(s) according to FORMAT (a-la C printf)

ps ps [-o COL1,COL2=HEADER] [-T]

Show list of processes

-o COL1,COL2=HEADER Select columns for display
-T Show threads

pwd pwd

Print the full filename of the current working directory

rdate [-sp] HOST

Get and possibly set the system date/time from a remote HOST

-s Set the system date/time (default)
-p Print the date/time

readlink [-fnv] FILE

Display the value of a symlink

-f Canonicalize by following all symlinks
-n Don't add newline
-v Verbose

realpath FILE...

Return the absolute pathnames of given FILE

reboot [-d DELAY] [-n] [-f]

Reboot the system

-d SEC Delay interval
-n Do not sync
-f Force (don't go through init)

renice {{-n INCREMENT} | PRIORITY} [[-p | -g | -u] ID...]

Change scheduling priority for a running process

-n Adjust current nice value (smaller is faster)
-p Process id(s) (default)
-g Process group id(s)
-u Process user name(s) and/or id(s)


Reset the screen

rev rev [FILE]...

Reverse lines of FILE

rm rm [-irf] FILE...

Remove (unlink) FILEs

-i Always prompt before removing
-f Never prompt
-R,-r Recurse


Remove DIRECTORY if it is empty

-p|--parents Include parents

rmmod [-wfa] [MODULE]...

Unload kernel modules

-w Wait until the module is no longer used
-f Force unload
-a Remove all unused modules (recursively)

route [{add|del|delete}]

Edit kernel routing tables

-n Don't resolve names
-e Display other/more information
-A inet{6} Select address family

rpm rpm -i PACKAGE.rpm; rpm -qp[ildc] PACKAGE.rpm

Manipulate RPM packages


-i Install package
-qp Query package
-qpi Show information
-qpl List contents
-qpd List documents
-qpc List config files

rpm2cpio package.rpm

Output a cpio archive of the rpm file

run-parts [-a ARG]... [-u UMASK] [--reverse] [--test] [--exit-on-error] DIRECTORY

Run a bunch of scripts in DIRECTORY

-a ARG Pass ARG as argument to scripts
-u UMASK Set UMASK before running scripts
--reverse Reverse execution order
--test Dry run
--exit-on-error Exit if a script exits with non-zero

sed sed [-inrE] [-f FILE]... [-e CMD]... [FILE]... or: sed [-inrE] CMD [FILE]...

-e CMD Add CMD to sed commands to be executed
-f FILE Add FILE contents to sed commands to be executed
-i[SFX] Edit files in-place (otherwise sends to stdout)
Optionally back files up, appending SFX
-n Suppress automatic printing of pattern space
-r,-E Use extended regex syntax

If no -e or -f, the first non-option argument is the sed command string. Remaining
arguments are input files (stdin if none).

seq seq [-w] [-s SEP] [FIRST [INC]] LAST

Print numbers from FIRST to LAST, in steps of INC. FIRST, INC default to 1.

-w Pad to last with leading zeros
-s SEP String separator

setkeycodes SCANCODE KEYCODE...

Set entries into the kernel's scancode-to-keycode map, allowing unusual keyboards to
generate usable keycodes.

SCANCODE may be either xx or e0xx (hexadecimal), and KEYCODE is given in decimal.

setsid PROG ARGS

Run PROG in a new session. PROG will have no controlling terminal and will not be
affected by keyboard signals (Ctrl-C etc). See setsid(2) for details.

sh sh [-/+OPTIONS] [-/+o OPT]... [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]

Unix shell interpreter

sha1sum [-c[sw]] [FILE]...

Print or check SHA1 checksums

-c Check sums against list in FILEs
-s Don't output anything, status code shows success
-w Warn about improperly formatted checksum lines

sha256sum [-c[sw]] [FILE]...

Print or check SHA256 checksums

-c Check sums against list in FILEs
-s Don't output anything, status code shows success
-w Warn about improperly formatted checksum lines

sha512sum [-c[sw]] [FILE]...

Print or check SHA512 checksums

-c Check sums against list in FILEs
-s Don't output anything, status code shows success
-w Warn about improperly formatted checksum lines

sleep [N]...

Pause for a time equal to the total of the args given, where each arg can have an
optional suffix of (s)econds, (m)inutes, (h)ours, or (d)ays

sort [-nrugMcszbdfimSTokt] [-o FILE] [-k start[.offset][opts][,end[.offset][opts]] [-t

Sort lines of text

-b Ignore leading blanks
-c Check whether input is sorted
-d Dictionary order (blank or alphanumeric only)
-f Ignore case
-g General numerical sort
-i Ignore unprintable characters
-k Sort key
-M Sort month
-n Sort numbers
-o Output to file
-k Sort by key
-t CHAR Key separator
-r Reverse sort order
-s Stable (don't sort ties alphabetically)
-u Suppress duplicate lines
-z Lines are terminated by NUL, not newline
-mST Ignored for GNU compatibility

start-stop-daemon [OPTIONS] [-S|-K] ... [-- ARGS...]

Search for matching processes, and then -K: stop all matching processes. -S: start a
process unless a matching process is found.

Process matching:

-u,--user USERNAME|UID Match only this user's processes
-n,--name NAME Match processes with NAME
in comm field in /proc/PID/stat
-x,--exec EXECUTABLE Match processes with this command
in /proc/PID/{exe,cmdline}
-p,--pidfile FILE Match a process with PID from the file
All specified conditions must match
-S only:
-x,--exec EXECUTABLE Program to run
-a,--startas NAME Zeroth argument
-b,--background Background
-N,--nicelevel N Change nice level
-c,--chuid USER[:[GRP]] Change to user/group
-m,--make-pidfile Write PID to the pidfile specified by -p
-K only:
-s,--signal SIG Signal to send
-t,--test Match only, exit with 0 if a process is found

-o,--oknodo Exit with status 0 if nothing is done
-v,--verbose Verbose
-q,--quiet Quiet

stat [OPTIONS] FILE...

Display file (default) or filesystem status

-c fmt Use the specified format
-f Display filesystem status
-L Follow links
-t Display info in terse form

Valid format sequences for files:

%a Access rights in octal
%A Access rights in human readable form
%b Number of blocks allocated (see %B)
%B The size in bytes of each block reported by %b
%d Device number in decimal
%D Device number in hex
%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
%n File name
%N File name, with -> TARGET if symlink
%o I/O block size
%s Total size, in bytes
%t Major device type in hex
%T Minor device type in hex
%u User ID of owner
%U User name of owner
%x Time of last access
%X Time of last access as seconds since Epoch
%y Time of last modification
%Y Time of last modification as seconds since Epoch
%z Time of last change
%Z Time of last change as seconds since Epoch

Valid format sequences for file systems:

%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 transfer)
%S Fundamental block size (for block counts)
%t Type in hex
%T Type in human readable form

strings [-afo] [-n LEN] [FILE]...

Display printable strings in a binary file

-a Scan whole file (default)
-f Precede strings with filenames
-n LEN At least LEN characters form a string (default 4)
-o Precede strings with decimal offsets

stty [-a|g] [-F DEVICE] [SETTING]...

Without arguments, prints baud rate, line discipline, and deviations from stty sane

-F DEVICE Open device instead of stdin
-a Print all current settings in human-readable form
-g Print in stty-readable form
[SETTING] See manpage

su su [OPTIONS] [-] [USER]

Run shell under USER (by default, root)

-,-l Clear environment, run shell as login shell
-p,-m Do not set new $HOME, $SHELL, $USER, $LOGNAME
-c CMD Command to pass to 'sh -c'
-s SH Shell to use instead of user's default

sulogin [-t N] [TTY]

Single user login

-t N Timeout

swapoff [-a] [DEVICE]

Stop swapping on DEVICE

-a Stop swapping on all swap devices

swapon [-a] [DEVICE]

Start swapping on DEVICE

-a Start swapping on all swap devices

switch_root [-c /dev/console] NEW_ROOT NEW_INIT [ARGS]

Free initramfs and switch to another root fs:

chroot to NEW_ROOT, delete all in /, move NEW_ROOT to /, execute NEW_INIT. PID must be
1. NEW_ROOT must be a mountpoint.

-c DEV Reopen stdio to DEV after switch


Write all buffered blocks to disk

sysctl [OPTIONS] [KEY[=VALUE]]...

Show/set kernel parameters

-e Don't warn about unknown keys
-n Don't show key names
-a Show all values
-w Set values
-p FILE Set values from FILE (default /etc/sysctl.conf)
-q Set values silently

syslogd [OPTIONS]

System logging utility (this version of syslogd ignores /etc/syslog.conf)

-n Run in foreground
-O FILE Log to FILE (default:/var/log/messages)
-l N Log only messages more urgent than prio N (1-8)
-S Smaller output
-R HOST[:PORT] Log to HOST:PORT (default PORT:514)
-L Log locally and via network (default is network only if -R)
-C[size_kb] Log to shared mem buffer (use logread to read it)

tac tac [FILE]...

Concatenate FILEs and print them in reverse

tail [OPTIONS] [FILE]...

Print last 10 lines of each FILE (or stdin) to stdout. With more than one FILE,
precede each with a filename header.

-f Print data as file grows
-s SECONDS Wait SECONDS between reads with -f
-n N[kbm] Print last N lines
-n +N[kbm] Start on Nth line and print the rest
-c [+]N[kbm] Print last N bytes
-q Never print headers
-v Always print headers

N may be suffixed by k (x1024), b (x512), or m (x1024^2).

tar tar -[cxtZzJjahmvO] [-f TARFILE] [-C DIR] [FILE]...

Create, extract, or list files from a tar file


c Create
x Extract
t List
f Name of TARFILE ('-' for stdin/out)
C Change to DIR before operation
v Verbose
Z (De)compress using compress
z (De)compress using gzip
J (De)compress using xz
j (De)compress using bzip2
a (De)compress using lzma
O Extract to stdout
h Follow symlinks
m Don't restore mtime

taskset [-p] [MASK] [PID | PROG ARGS]

Set or get CPU affinity

-p Operate on an existing PID

tee tee [-ai] [FILE]...

Copy stdin to each FILE, and also to stdout

-a Append to the given FILEs, don't overwrite
-i Ignore interrupt signals (SIGINT)

telnet [-a] [-l USER] HOST [PORT]

Connect to telnet server

-a Automatic login with $USER variable
-l USER Automatic login as USER

telnetd [OPTIONS]

Handle incoming telnet connections

-l LOGIN Exec LOGIN on connect
-f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue
-K Close connection as soon as login exits
(normally wait until all programs close slave pty)
-p PORT Port to listen on
-b ADDR[:PORT] Address to bind to
-F Run in foreground
-i Inetd mode


Check file types, compare values etc. Return a 0/1 exit code depending on logical


Transfer a file from/to tftp server

-l FILE Local FILE
-r FILE Remote FILE
-g Get file
-p Put file
-b SIZE Transfer blocks of SIZE octets

time [-v] PROG ARGS

Run PROG, display resource usage when it exits

-v Verbose

timeout [-t SECS] [-s SIG] PROG ARGS

Runs PROG. Sends SIG to it if it is not gone in SECS seconds. Defaults: SECS: 10,

top top [-b] [-nCOUNT] [-dSECONDS]

Provide a view of process activity in real time. Read the status of all processes
from /proc each SECONDS and display a screenful of them. Keys:

N/M/P/T: sort by pid/mem/cpu/time
R: reverse sort
H: toggle threads
Q,^C: exit


-b Batch mode
-n N Exit after N iterations
-d N Delay between updates

touch [-c] [-d DATE] [-t DATE] [-r FILE] FILE...

Update the last-modified date on the given FILE[s]

-c Don't create files
-h Don't follow links
-d DT Date/time to use
-t DT Date/time to use
-r FILE Use FILE's date/time

tr tr [-cds] STRING1 [STRING2]

Translate, squeeze, or delete characters from stdin, writing to stdout

-c Take complement of STRING1
-d Delete input characters coded STRING1
-s Squeeze multiple output characters of STRING2 into one character

traceroute [-46FIldnrv] [-f 1ST_TTL] [-m MAXTTL] [-p PORT] [-q PROBES] [-s

Trace the route to HOST

-4,-6 Force IP or IPv6 name resolution
-F Set the don't fragment bit
-I Use ICMP ECHO instead of UDP datagrams
-l Display the TTL value of the returned packet
-d Set SO_DEBUG options to socket
-n Print numeric addresses
-r Bypass routing tables, send directly to HOST
-v Verbose
-m Max time-to-live (max number of hops)
-p Base UDP port number used in probes
(default 33434)
-q Number of probes per TTL (default 3)
-s IP address to use as the source address
-t Type-of-service in probe packets (default 0)
-w Time in seconds to wait for a response (default 3)
-g Loose source route gateway (8 max)

traceroute6 [-dnrv] [-m MAXTTL] [-p PORT] [-q PROBES] [-s SRC_IP] [-t TOS] [-w

Trace the route to HOST

-d Set SO_DEBUG options to socket
-n Print numeric addresses
-r Bypass routing tables, send directly to HOST
-v Verbose
-m Max time-to-live (max number of hops)
-p Base UDP port number used in probes
(default is 33434)
-q Number of probes per TTL (default 3)
-s IP address to use as the source address
-t Type-of-service in probe packets (default 0)
-w Time in seconds to wait for a response (default 3)


Return an exit code of TRUE \fIs0(0)

tty tty

Print file name of stdin's terminal

-s Print nothing, only return exit status

tunctl [-f device] ([-t name] | -d name)

Create or delete tun interfaces

-f name tun device (/dev/net/tun)
-t name Create iface 'name'
-d name Delete iface 'name'

udhcpc [-fbqaRB] [-t N] [-T SEC] [-A SEC/-n] [-i IFACE] [-s PROG] [-p PIDFILE]
[-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]...

-i,--interface IFACE Interface to use (default eth0)
-s,--script PROG Run PROG at DHCP events (default /etc/udhcpc/default.script)
-p,--pidfile FILE Create pidfile
-B,--broadcast Request broadcast replies
-t,--retries N Send up to N discover packets (default 3)
-T,--timeout SEC Pause between packets (default 3)
-A,--tryagain SEC Wait if lease is not obtained (default 20)
-n,--now Exit if lease is not obtained
-q,--quit Exit after obtaining lease
-R,--release Release IP on exit
-f,--foreground Run in foreground
-b,--background Background if lease is not obtained
-S,--syslog Log to syslog too
-a,--arping Use arping to validate offered address
-r,--request IP Request this IP address
-o,--no-default-options Don't request any options (unless -O is given)
-O,--request-option OPT Request option OPT from server (cumulative)
-x OPT:VAL Include option OPT in sent packets (cumulative)
Examples of string, numeric, and hex byte opts:
-x hostname:bbox - option 12
-x lease:3600 - option 51 (lease time)
-x 0x3d:0100BEEFC0FFEE - option 61 (client id)
-F,--fqdn NAME Ask server to update DNS mapping for NAME
-V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')
-C,--clientid-none Don't send MAC as client identifier

USR1 Renew lease
USR2 Release lease

udhcpd [-fS] [-I ADDR] [CONFFILE]

DHCP server

-f Run in foreground
-S Log to syslog too
-I ADDR Local address


Unmount file systems

-a Unmount all file systems
-r Try to remount devices as read-only if mount is busy
-l Lazy umount (detach filesystem)
-f Force umount (i.e., unreachable NFS server)
-D Don't free loop device even if it has been used

uname [-amnrspv]

Print system information

-a Print all
-m The machine (hardware) type
-n Hostname
-r OS release
-s OS name (default)
-p Processor type
-v OS version

uncompress [-cf] [FILE]...

Decompress .Z file[s]

-c Write to stdout
-f Overwrite

unexpand [-fa][-t N] [FILE]...

Convert spaces to tabs, writing to stdout

-a,--all Convert all blanks
-f,--first-only Convert only leading blanks
-t,--tabs=N Tabstops every N chars

uniq [-cdu][-f,s,w N] [INPUT [OUTPUT]]

Discard duplicate lines

-c Prefix lines by the number of occurrences
-d Only print duplicate lines
-u Only print unique lines
-f N Skip first N fields
-s N Skip first N chars (after any skipped fields)
-w N Compare N characters in line

unix2dos [-ud] [FILE]

Convert FILE in-place from Unix to DOS format. When no file is given, use

-u dos2unix
-d unix2dos

unlzma [-cf] [FILE]...

Decompress FILE (or stdin)

-c Write to stdout
-f Force

unlzop [-cfvCF] [FILE]...

-c Write to stdout
-f Force
-v Verbose
-F Don't store or verify checksum

unxz [-cf] [FILE]...

Decompress FILE (or stdin)

-c Write to stdout
-f Force

unzip [-lnopq] FILE[.zip] [FILE]... [-x FILE...] [-d DIR]

Extract FILEs from ZIP archive

-l List contents (with -q for short form)
-n Never overwrite files (default: ask)
-o Overwrite
-p Print to stdout
-q Quiet
-x FILE Exclude FILEs
-d DIR Extract into DIR


Display the time since the last boot

usleep N

Pause for N microseconds

uudecode [-o OUTFILE] [INFILE]

Uudecode a file Finds OUTFILE in uuencoded source unless -o is given

uuencode [-m] [FILE] STORED_FILENAME

Uuencode FILE (or stdin) to stdout

-m Use base64 encoding per RFC1521


Create and remove virtual ethernet devices

set_flag IFACE 0|1 VLAN_QOS
set_name_type NAME_TYPE

vi vi [OPTIONS] [FILE]...


-c CMD Initial command to run ($EXINIT also available)
-R Read-only
-H List available features

watch [-n SEC] [-t] PROG ARGS

Run PROG periodically

-n Loop period in seconds (default 2)
-t Don't print header

watchdog [-t N[ms]] [-T N[ms]] [-F] DEV

Periodically write to watchdog device DEV

-T N Reboot after N seconds if not reset (default 60)
-t N Reset every N seconds (default 30)
-F Run in foreground

Use 500ms to specify period in milliseconds

wc wc [-cmlwL] [FILE]...

Count lines, words, and bytes for each FILE (or stdin)

-c Count bytes
-m Count characters
-l Count newlines
-w Count words
-L Print longest line length

wget [-c|--continue] [-s|--spider] [-q|--quiet] [-O|--output-document FILE]
[--header 'header: value'] [-Y|--proxy on/off] [-P DIR] [-U|--user-agent

Retrieve files via HTTP or FTP

-s Spider mode - only check file existence
-c Continue retrieval of aborted transfer
-q Quiet
-P DIR Save to DIR (default .)
-O FILE Save to FILE ('-' for stdout)
-U STR Use STR for User-Agent header
-Y Use proxy ('on' or 'off')

which [COMMAND]...

Locate a COMMAND

who who [-a]

Show who is logged on

-a Show all
-H Print column headers


Print the user name associated with the current effective user id


Run PROG on every item given by stdin

-p Ask user whether to run each command
-r Don't run command if input is empty
-0 Input is separated by NUL characters
-t Print the command on stderr before execution
-e[STR] STR stops input processing
-n N Pass no more than N args to PROG
-s N Pass command line of no more than N bytes
-x Exit if size is exceeded

xz xz -d [-cf] [FILE]...

Decompress FILE (or stdin)

-d Decompress
-c Write to stdout
-f Force

xzcat [FILE]...

Decompress to stdout

yes yes [STRING]

Repeatedly output a line with STRING, or 'y'

zcat [FILE]...

Decompress to stdout


GNU Libc (glibc) uses the Name Service Switch (NSS) to configure the behavior of the C
library for the local environment, and to configure how it reads system data, such as
passwords and group information. This is implemented using an /etc/nsswitch.conf
configuration file, and using one or more of the /lib/libnss_* libraries. BusyBox tries
to avoid using any libc calls that make use of NSS. Some applets however, such as login
and su, will use libc functions that require NSS.

If you enable CONFIG_USE_BB_PWD_GRP, BusyBox will use internal functions to directly
access the /etc/passwd, /etc/group, and /etc/shadow files without using NSS. This may
allow you to run your system without the need for installing any of the NSS configuration
files and libraries.

When used with glibc, the BusyBox 'networking' applets will similarly require that you
install at least some of the glibc NSS stuff (in particular, /etc/nsswitch.conf,
/lib/libnss_dns*, /lib/libnss_files*, and /lib/libresolv*).

Shameless Plug: As an alternative, one could use a C library such as uClibc. In addition
to making your system significantly smaller, uClibc does not require the use of any NSS
support files or libraries.


Denis Vlasenko <[email protected]>


The following people have contributed code to BusyBox whether they know it or not. If you
have written code included in BusyBox, you should probably be listed here so you can
obtain your bit of eternal glory. If you should be listed here, or the description of
what you have done needs more detail, or is incorrect, please send in an update.

Emanuele Aina <[email protected]>

Erik Andersen <[email protected]>

Tons of new stuff, major rewrite of most of the
core apps, tons of new apps as noted in header files.
Lots of tedious effort writing these boring docs that
nobody is going to actually read.

Laurence Anderson <[email protected]>

rpm2cpio, unzip, get_header_cpio, read_gz interface, rpm

Jeff Angielski <[email protected]>

ftpput, ftpget

Edward Betts <[email protected]>

expr, hostid, logname, whoami

John Beppu <[email protected]>

du, nslookup, sort

Brian Candler <[email protected]>


Randolph Chung <[email protected]>

fbset, ping, hostname

Dave Cinege <[email protected]>

more(v2), makedevs, dutmp, modularization, auto links file,
various fixes, Linux Router Project maintenance

Jordan Crouse <[email protected]>


Magnus Damm <[email protected]>

tftp client insmod powerpc support

Larry Doolittle <[email protected]>

pristine source directory compilation, lots of patches and fixes.

Glenn Engel <[email protected]>


Gennady Feldman <[email protected]>

Sysklogd (single threaded syslogd, IPC Circular buffer support,
logread), various fixes.

Karl M. Hegbloom <[email protected]>

cp_mv.c, the test suite, various fixes to utility.c, &c.

Daniel Jacobowitz <[email protected]>


Matt Kraai <[email protected]>

documentation, bugfixes, test suite

Stephan Linz <[email protected]>

ipcalc, Red Hat equivalence

John Lombardo <[email protected]>


Glenn McGrath <[email protected]>

Common unarchiving code and unarchiving applets, ifupdown, ftpgetput,
nameif, sed, patch, fold, install, uudecode.
Various bugfixes, review and apply numerous patches.

Manuel Novoa III <[email protected]>

cat, head, mkfifo, mknod, rmdir, sleep, tee, tty, uniq, usleep, wc, yes,
mesg, vconfig, make_directory, parse_mode, dirname, mode_string,
get_last_path_component, simplify_path, and a number trivial libbb routines

also bug fixes, partial rewrites, and size optimizations in
ash, basename, cal, cmp, cp, df, du, echo, env, ln, logname, md5sum, mkdir,
mv, realpath, rm, sort, tail, touch, uname, watch, arith, human_readable,
interface, dutmp, ifconfig, route

Vladimir Oleynik <[email protected]>

cmdedit; xargs(current), httpd(current);
ports: ash, crond, fdisk, inetd, stty, traceroute, top;
locale, various fixes
and irreconcilable critic of everything not perfect.

Bruce Perens <[email protected]>

Original author of BusyBox in 1995, 1996. Some of his code can
still be found hiding here and there...

Tim Riker <[email protected]>

bug fixes, member of fan club

Kent Robotti <[email protected]>

reset, tons and tons of bug reports and patches.

Chip Rosenthal <[email protected]>, <[email protected]>

wget - Contributed by permission of Covad Communications

Pavel Roskin <[email protected]>

Lots of bugs fixes and patches.

Gyepi Sam <[email protected]>

Remote logging feature for syslogd

Linus Torvalds <[email protected]>

mkswap, fsck.minix, mkfs.minix

Mark Whitley <[email protected]>

grep, sed, cut, xargs(previous),
style-guide, new-applet-HOWTO, bug fixes, etc.

Charles P. Wright <[email protected]>

gzip, mini-netcat(nc)

Enrique Zanardi <[email protected]>

tarcat (since removed), loadkmap, various fixes, Debian maintenance

Tito Ragusa <[email protected]>

devfsd and size optimizations in strings, openvt and deallocvt.

Paul Fox <[email protected]>

vi editing mode for ash, various other patches/fixes

Roberto A. Foglietta <[email protected]>

port: dnsd

Bernhard Reutner-Fischer <[email protected]>


Mike Frysinger <[email protected]>

initial e2fsprogs, printenv, setarch, sum, misc

Jie Zhang <[email protected]>

fixed two bugs in msh and hush (exitcode of killed processes)

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