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BUSYBOX(1) busybox BUSYBOX(1)


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 configuration.

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, arch, arp, arping, ascii, ash, awk,
        base64, basename, bc, blkdiscard, blkid, blockdev, brctl, bunzip2,
        bzcat, bzip2, cal, cat, chgrp, chmod, chown, chroot, chvt, clear,
        cmp, cp, cpio, crc32, cttyhack, cut, date, dc, dd, deallocvt,
        depmod, devmem, df, diff, dirname, dmesg, dnsdomainname, dos2unix,
        du, dumpkmap, dumpleases, echo, egrep, env, expand, expr, factor,
        fallocate, false, fatattr, fdisk, fgrep, find, findfs, fold, free,
        freeramdisk, fsfreeze, fstrim, ftpget, ftpput, getopt, getty, grep,
        groups, gunzip, gzip, halt, head, hexdump, hostid, hostname, httpd,
        hwclock, i2cdetect, i2cdump, i2cget, i2cset, i2ctransfer, id,
        ifconfig, ifdown, ifup, init, insmod, ionice, ip, ipcalc, ipneigh,
        kill, killall, klogd, last, less, link, linux32, linux64, linuxrc,
        ln, loadfont, loadkmap, logger, login, logname, logread, losetup,
        ls, lsmod, lsscsi, lzcat, lzma, lzop, md5sum, mdev, microcom, mim,
        mkdir, mkdosfs, mke2fs, mkfifo, mknod, mkpasswd, mkswap, mktemp,
        modinfo, modprobe, more, mount, mt, mv, nameif, nc, netstat, nl,
        nologin, nproc, nsenter, nslookup, nuke, od, openvt, partprobe,
        paste, patch, pidof, ping, ping6, pivot_root, poweroff, printf, ps,
        pwd, rdate, readlink, realpath, reboot, renice, reset, resume, rev,
        rm, rmdir, rmmod, route, rpm, rpm2cpio, run-init, run-parts, sed,
        seq, setkeycodes, setpriv, setsid, sh, sha1sum, sha256sum, sha3sum,
        sha512sum, shred, shuf, sleep, sort, ssl_client, start-stop-daemon,
        stat, strings, stty, svc, svok, swapoff, swapon, switch_root, sync,
        sysctl, syslogd, tac, tail, tar, taskset, tee, telnet, test, tftp,
        time, timeout, top, touch, tr, traceroute, traceroute6, true,
        truncate, ts, tty, ubirename, udhcpc, udhcpd, uevent, umount, uname,
        uncompress, unexpand, uniq, unix2dos, unlink, unlzma, unshare, unxz,
        unzip, uptime, usleep, uudecode, uuencode, vconfig, vi, w, watch,
        watchdog, wc, wget, which, who, whoami, xargs, xxd, xz, xzcat, yes,



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/]
        -a FILE Action file [/etc/acpid.conf]
        -M FILE Map file [/etc/]

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

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

Read or set kernel time variables. See adjtimex(2)

        -q      Quiet
        -o OFF  Time offset, microseconds
        -f FREQ Frequency adjust, integer kernel units (65536 is 1ppm)
        -t TICK Microseconds per tick, usually 10000
                (positive -t or -f values make clock run faster)
        -p TCONST
ar x|p|t [-ov] ARCHIVE [FILE]...

Extract or list FILEs from an ar archive

        x       Extract
        p       Extract to stdout
        t       List
        -o      Restore mtime
        -v      Verbose

Print system architecture

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 HOSTNAME HWADDR [netmask MASK] pub [-v] [-H HWTYPE] [-i IF] -Ds HOSTNAME IFACE [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
        -D              Read HWADDR from IFACE
        -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              Exit with 1 if DST_IP replies
        -U              Unsolicited ARP mode, update your neighbors
        -A              ARP answer mode, update your neighbors
        -c N            Stop after sending N ARP requests
        -w TIMEOUT      Seconds to wait for ARP reply
        -I IFACE        Interface to use (default eth0)
        -s SRC_IP       Sender IP address
        DST_IP          Target IP address
ash [-il] [-|+Cabefmnuvx] [-|+o OPT]... [-c 'SCRIPT' [ARG0 ARGS] | FILE ARGS | -s ARGS]

Unix shell interpreter


        -v VAR=VAL      Set variable
        -F SEP          Use SEP as field separator
        -f FILE         Read program from FILE
        -e AWK_PROGRAM
base64 [-d] [-w COL] [FILE]

Base64 encode or decode FILE to standard output

        -d      Decode data
        -w COL  Wrap lines at COL (default 76, 0 disables)
basename FILE [SUFFIX] | -a FILE... | -s SUFFIX FILE...

Strip directory path and SUFFIX from FILE

        -a              All arguments are FILEs
        -s SUFFIX       Remove SUFFIX (implies -a)
bc [-sqlw] [FILE]...

Arbitrary precision calculator

        -q      Quiet
        -l      Load standard library
        -s      Be POSIX compatible
        -w      Warn if extensions are used

$BC_LINE_LENGTH changes output width

blkdiscard [-o OFS] [-l LEN] [-s] DEVICE

Discard sectors on DEVICE

        -o OFS  Byte offset into device
        -l LEN  Number of bytes to discard
        -s      Perform a secure discard
blkid [BLOCKDEV]...

Print UUIDs of all filesystems


        --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
        --getra         Get readahead in 512-byte sectors
        --setra SECTORS Set readahead
        --flushbufs     Flush buffers
        --rereadpt      Reread partition table

Manage ethernet bridges Commands:

        addbr BRIDGE            Create BRIDGE
        delbr BRIDGE            Delete BRIDGE
        addif BRIDGE IFACE      Add IFACE to BRIDGE
        delif BRIDGE IFACE      Delete IFACE from BRIDGE
bunzip2 [-cfk] [FILE]...

Decompress FILEs (or stdin)

        -c      Write to stdout
        -f      Force
        -k      Keep input files
        -t      Test integrity
bzcat [FILE]...

Decompress to stdout

bzip2 [-cfkdt123456789] [FILE]...

Compress FILEs (or stdin) with bzip2 algorithm

        -1..9   Compression level
        -d      Decompress
        -c      Write to stdout
        -f      Force
        -k      Keep input files
        -t      Test integrity
cal [-jmy] [[MONTH] YEAR]

Display a calendar

        -j      Use julian dates
        -m      Week starts on Monday
        -y      Display the entire year
cat [-nbvteA] [FILE]...

Print FILEs to stdout

        -n      Number output lines
        -b      Number nonempty lines
        -v      Show nonprinting characters as ^x or M-x
        -t      ...and tabs as ^I
        -e      ...and end lines with $
        -A      Same as -vte
chgrp [-RhLHPcvf]... GROUP FILE...

Change the group membership of FILEs to GROUP

        -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)
        -R      Recurse
        -c      List changed files
        -v      Verbose
        -f      Hide errors
chmod [-Rcvf] MODE[,MODE]... FILE...

MODE is octal number (bit pattern sstrwxrwxrwx) or [ugoa]{+|-|=}[rwxXst]

        -R      Recurse
        -c      List changed files
        -v      Verbose
        -f      Hide errors
chown [-RhLHPcvf]... USER[:[GRP]] FILE...

Change the owner and/or group of FILEs to USER and/or GRP

        -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)
        -R      Recurse
        -c      List changed files
        -v      Verbose
        -f      Hide errors

Run PROG with root directory set to NEWROOT

chvt N

Change the foreground virtual terminal to /dev/ttyN


Clear screen

cmp [-ls] [-n NUM] 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
        -n NUM  Compare at most NUM bytes
cp [-arPLHpfinlsTu] SOURCE DEST or: cp [-arPLHpfinlsu] SOURCE... { -t DIRECTORY | DIRECTORY }


        -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
        -n      Don't overwrite
        -l,-s   Create (sym)links
        -T      Refuse to copy if DEST is a directory
        -t DIR  Copy all SOURCEs into DIR
        -u      Copy only newer files
cpio [-dmvu] [-F FILE] [-R USER[:GRP]] [-H newc] [-tio] [EXTR_FILE]...

Extract (-i) or list (-t) files from a cpio archive, or take file list from stdin and create an archive (-o)

Main operation mode:

        -t      List
        -i      Extract EXTR_FILEs (or all)
        -o      Create (requires -H newc)
        -H newc Archive format
        -d      Make leading directories
        -m      Restore mtime
        -v      Verbose
        -u      Overwrite
        -F FILE Input (-t,-i,-p) or output (-o) file
        -R USER[:GRP]   Set owner of created files
        -L      Dereference symlinks
        -0      NUL terminated input
crc32 FILE...

Calculate CRC32 checksum of FILEs

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 [OPTIONS] [FILE]...

Print selected fields from FILEs to stdout

        -b LIST Output only bytes from LIST
        -c LIST Output only characters from LIST
        -d SEP  Field delimiter for input (default -f TAB, -F run of whitespace)
        -O SEP  Field delimiter for output (default = -d for -f, one space for -F)
        -D      Don't sort/collate sections or match -fF lines without delimiter
        -f LIST Print only these fields (-d is single char)
        -F LIST Print only these fields (-d is regex)
        -s      Output only lines containing delimiter
        -n      Ignored
date [OPTIONS] [+FMT] [[-s] TIME]

Display time (using +FMT), or set time

        -u              Work in UTC (don't convert to local time)
        [-s] TIME       Set time to TIME
        -d TIME         Display TIME, not 'now'
        -D FMT          FMT (strptime format) for -s/-d TIME conversion
        -r FILE         Display last modification time of FILE
        -R              Output RFC-2822 date
        -I[SPEC]        Output ISO-8601 date
                        SPEC=date (default), hours, minutes, seconds or ns

Recognized TIME formats:

        YYYY-MM-DD hh:mm[:ss]
        'date TIME' form accepts MMDDhhmm[[YY]YY][.ss] instead
dc [-x] [-eSCRIPT]... [-fFILE]... [FILE]...

Tiny RPN calculator. Operations: Arithmetic: + - * / % ^ ~ - divide with remainder | - modular exponentiation v - square root p - print top of the stack without popping f - print entire stack k - pop the value and set precision i - pop the value and set input radix o - pop the value and set output radix Examples: dc -e'2 2 + p' -> 4, dc -e'8 8 * 2 2 + / p' -> 16

dd [if=FILE] [of=FILE] [ibs=N obs=N/bs=N] [count=N] [skip=N] [seek=N] [conv=notrunc|noerror|sync|fsync] [iflag=skip_bytes|count_bytes|fullblock|direct] [oflag=seek_bytes|append|direct]

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
        iflag=skip_bytes        skip=N is in bytes
        iflag=count_bytes       count=N is in bytes
        oflag=seek_bytes        seek=N is in bytes
        iflag=direct    O_DIRECT input
        oflag=direct    O_DIRECT output
        iflag=fullblock Read full blocks
        oflag=append    Open output in append mode
        status=noxfer   Suppress rate output
        status=none     Suppress all output

N may be suffixed by c (1), w (2), b (512), kB (1000), k (1024), MB, M, GB, 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 [-PkmhTai] [-B SIZE] [-t TYPE] [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)
        -T      Print filesystem type
        -t TYPE Print only mounts of this type
        -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 [-cr] [-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
        -r              Print raw message buffer
dos2unix [-ud] [FILE]

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

        -u      dos2unix
        -d      unix2dos
du [-aHLdclsxhmk] [FILE]...

Summarize disk space used for FILEs (or directories)

        -a      Show file sizes too
        -b      Apparent size (including holes)
        -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] [-d] [-f LEASEFILE]

Display DHCP leases granted by udhcpd

        -f FILE Lease file
        -r      Show remaining time
        -a      Show expiration time
        -d      Show time in seconds
echo [-neE] [ARG]...

Print ARGs to stdout

        -n      No trailing newline
        -e      Interpret backslash escapes (\t=tab etc)
        -E      Don't interpret backslash escapes (default)
env [-i0] [-u NAME]... [-] [NAME=VALUE]... [PROG ARGS]

Print current environment or run PROG after setting up environment

        -, -i   Start with empty environment
        -0      NUL terminated output
        -u NAME Remove variable from environment
expand [-i] [-t N] [FILE]...

Convert tabs to spaces, writing to stdout

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

Print the value of EXPRESSION


        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
        ARG1 > ARG2
        ARG1 + ARG2     Sum of ARG1 and ARG2. Similarly:
        ARG1 - ARG2
        ARG1 * ARG2
        ARG1 / ARG2
        ARG1 % ARG2
        STRING : REGEXP         Anchored pattern match of REGEXP in STRING
        match STRING REGEXP     Same as STRING : REGEXP
        substr STRING POS LEN   Substring of STRING, POS counts 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 '/'
        (EXPRESSION)            Value of EXPRESSION

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.

factor [NUMBER]...

Print prime factors

fallocate [-o OFS] -l LEN FILE

Preallocate space for FILE

        -o OFS  Offset of range
        -l LEN  Length of range
fatattr [-+rhsvda] FILE...

Change file attributes on FAT filesystem

        -       Clear attributes
        +       Set attributes
        r       Read only
        h       Hidden
        s       System
        v       Volume label
        d       Directory
        a       Archive
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
        -H HEADS        Typically 255
        -S SECTORS      Typically 63
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,s,p)
        -executable     File is executable
        -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
        -atime DAYS     atime +N/-N/N days in the past
        -ctime DAYS     ctime +N/-N/N days in the past
        -mmin MINS      mtime is greater than (+N), less than (-N),
                        or exactly N minutes in the past
        -amin MINS      atime +N/-N/N minutes in the past
        -cmin MINS      ctime +N/-N/N minutes in the past
        -newer FILE     mtime is more recent than FILE's
        -inum N         File has inode number N
        -samefile FILE  File is same as FILE
        -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
        -empty          Match empty file/directory
        -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
        -exec CMD ARG + Run CMD with {} replaced by list of file names
        -quit           Exit
findfs LABEL=label or UUID=uuid

Find a filesystem device based on a label or UUID

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

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

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

Display free and used memory

freeramdisk DEVICE

Free all memory used by the specified ramdisk

fsfreeze --[un]freeze MOUNTPOINT

Flush and halt writes to MOUNTPOINT


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

Download a file via FTP

        -c      Continue previous transfer
        -v      Verbose
        -u USER Username
        -p PASS Password
        -P PORT

Upload a file to a FTP server

        -v      Verbose
        -u USER Username
        -p PASS Password
        -P PORT

        -a              Allow long options starting with single -
        -l LOPT[,...]   Long options to recognize
        -n PROGNAME     The name under which errors are reported
        -o OPTSTRING    Short options to recognize
        -q              No error messages on unrecognized options
        -Q              No normal output
        -s SHELL        Set shell quoting conventions
        -T              Version test (exits with 4)
        -u              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 [-HhnlLoqvsrRiwFEz] [-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
        -R      Recurse and dereference symlinks
        -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      NUL terminated input
        -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 groups USER is in

gunzip [-cfkt] [FILE]...

Decompress FILEs (or stdin)

        -c      Write to stdout
        -f      Force
        -k      Keep input files
        -t      Test integrity
gzip [-cfkdt] [FILE]...

Compress FILEs (or stdin)

        -d      Decompress
        -c      Write to stdout
        -f      Force
        -k      Keep input files
        -t      Test integrity
halt [-d DELAY] [-nfw]

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 FILEs (or stdin). With more than one FILE, precede each with a filename header.

        -n N[bkm]       Print first N lines
        -n -N[bkm]      Print all except N last lines
        -c [-]N[bkm]    Print first N bytes
                        (b:*512 k:*1024 m:*1024^2)
        -q              Never print headers
        -v              Always print headers
hexdump [-bcdoxCv] [-e FMT] [-f FMT_FILE] [-n LEN] [-s OFS] [FILE]...

Display FILEs (or stdin) in a user specified format

        -b              1-byte octal display
        -c              1-byte character display
        -d              2-byte decimal display
        -o              2-byte octal display
        -x              2-byte hex display
        -C              hex+ASCII 16 bytes per line
        -v              Show all (no dup folding)
        -e FORMAT_STR   Example: '16/1 "%02x|""\n"'
        -f FORMAT_FILE
        -n LENGTH       Show only first LENGTH bytes
        -s OFFSET       Skip OFFSET bytes

Print out a unique 32-bit identifier for the machine

hostname [-sidf] [HOSTNAME | -F FILE]

Show 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              Run in foreground
        -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)
        -m STRING       MD5 crypt STRING
        -e STRING       HTML encode STRING
        -d STRING       URL decode STRING
hwclock [-swul] [--systz] [-f DEV]

Show or set hardware clock (RTC)

        -s      Set system time from RTC
        -w      Set RTC from system time
        --systz Set in-kernel timezone, correct system time
                if RTC is kept in local time
        -f DEV  Use specified device (e.g. /dev/rtc2)
        -u      Assume RTC is kept in UTC
        -l      Assume RTC is kept in local time
                (if neither is given, read from /etc/adjtime)
i2cdetect -l | -F I2CBUS | [-ya] [-q|-r] I2CBUS [FIRST LAST]

Detect I2C chips

        -l      List installed buses
        -F BUS# List functionalities on this bus
        -y      Disable interactive mode
        -a      Force scanning of non-regular addresses
        -q      Use smbus quick write commands for probing (default)
        -r      Use smbus read byte commands for probing
        FIRST and LAST limit probing range
i2cdump [-fy] [-r FIRST-LAST] BUS ADDR [MODE]

Examine I2C registers

        I2CBUS  I2C bus number
        ADDRESS 0x03-0x77
MODE is:
        b       Byte (default)
        w       Word
        W       Word on even register addresses
        i       I2C block
        s       SMBus block
        c       Consecutive byte
        Append p for SMBus PEC
        -f      Force access
        -y      Disable interactive mode
        -r      Limit the number of registers being accessed

Read from I2C/SMBus chip registers

        I2CBUS  I2C bus number
        ADDRESS 0x03-0x77
MODE is:
        b       Read byte data (default)
        w       Read word data
        c       Write byte/read byte
        Append p for SMBus PEC
        -f      Force access
        -y      Disable interactive mode

Set I2C registers

        I2CBUS  I2C bus number
        ADDRESS 0x03-0x77
MODE is:
        c       Byte, no value
        b       Byte data (default)
        w       Word data
        i       I2C block data
        s       SMBus block data
        Append p for SMBus PEC
        -f      Force access
        -y      Disable interactive mode
        -r      Read back and compare the result
        -m MASK Mask specifying which bits to write
i2ctransfer [-fay] I2CBUS { rLENGTH[@ADDR] | wLENGTH[@ADDR] DATA...}...

Read/write I2C data in one transfer

        -f      Force access to busy addresses
        -a      Force access to non-regular addresses
        -y      Disable interactive mode
id [-ugGnr] [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] [IFACE] [ADDRESS]

Configure a network interface

        [add ADDRESS[/PREFIXLEN]]
        [del ADDRESS[/PREFIXLEN]]
        [[-]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 [-nvf] [-i FILE] -a | IFACE...

        -a      Deconfigure all interfaces
        -i FILE Use FILE instead of /etc/network/interfaces
        -n      Dry run
        -v      Print out what would happen before doing it
        -f      Force
ifup [-nvf] [-i FILE] -a | IFACE...

        -a      Configure all interfaces
        -i FILE Use FILE instead of /etc/network/interfaces
        -n      Dry run
        -v      Print out what would happen before doing it
        -f      Force

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

HUP: reload /etc/inittab TSTP: stop respawning until CONT QUIT: re-exec another init USR1/TERM/USR2/INT: run halt/reboot/poweroff/Ctrl-Alt-Del script


Load kernel module

ionice [-c 1-3] [-n 0-7] [-t] { -p PID | PROG ARGS }

Change I/O priority and class

        -c N    Class. 1:realtime 2:best-effort 3:idle
        -n N    Priority
        -t      Ignore errors
ip [OPTIONS] address|route|link|tunnel|neigh|rule [ARGS]

OPTIONS := -f[amily] inet|inet6|link | -o[neline]

ip addr add|del IFADDR dev IFACE | show|flush [dev IFACE] [to PREFIX] ip route list|flush|add|del|change|append|replace|test ROUTE ip link set IFACE [up|down] [arp on|off] [multicast on|off] [promisc on|off] [mtu NUM] [name NAME] [qlen NUM] [address MAC] [master IFACE | nomaster] [netns PID] ip tunnel add|change|del|show [NAME] [mode ipip|gre|sit] [remote ADDR] [local ADDR] [ttl TTL] ip neigh show|flush [to PREFIX] [dev DEV] [nud STATE] ip rule [list] | add|del SELECTOR ACTION

ipcalc [-bnmphs] ADDRESS[/PREFIX] [NETMASK]

Calculate and display network settings from IP address

        -b      Broadcast address
        -n      Network address
        -m      Default netmask for IP
        -p      Prefix for IP/NETMASK
        -h      Resolved host name
        -s      No error messages
ipneigh show|flush [to PREFIX] [dev DEV] [nud STATE]
kill [-l] [-SIG] PID...

Send a signal (default: TERM) to given PIDs

        -l      List all signal names and numbers
killall [-lq] [-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]

Log kernel messages to syslog

        -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 [-EFIMmNSRh~] [FILE]...

View FILE (or stdin) one screenful at a time

        -E      Quit once the end of a file is reached
        -F      Quit if entire file fits on first screen
        -I      Ignore case in all searches
        -M,-m   Display status line with line numbers
                and percentage through the file
        -N      Prefix line number to each line
        -S      Truncate long lines
        -R      Remove color escape codes in input
        -~      Suppress ~s displayed past EOF

Create hard LINK to FILE

ln [-sfnbtv] [-S SUF] TARGET... LINK|DIR

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      Treat LINK as a file, not DIR
        -v      Verbose
loadfont < font

Load a console font from stdin

loadkmap < keymap

Load a binary keyboard translation table from stdin

logger [-s] [-t TAG] [-p PRIO] [MESSAGE]

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 (number 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 HOST Host user came from (for network logins)
        -p      Preserve environment

$LOGIN_TIMEOUT Seconds (default 60, 0 - disable)


Print the name of the current user

logread [-fF]

Show messages in syslogd's circular buffer

        -f      Output data as log grows
        -F      Same as -f, but dump buffer first
losetup [-rP] [-o OFS] {-f|LOOPDEV} FILE: associate loop devices losetup -c LOOPDEV: reread file size losetup -d LOOPDEV: disassociate losetup -a: show status losetup -f: show next free loop device

        -o OFS  Start OFS bytes into FILE
        -P      Scan for partitions
        -r      Read-only
        -f      Show/use next free loop device
ls [-1AaCxdLHRFplinshrSXvctu] [-w WIDTH] [FILE]...

List directory contents

        -1      One column output
        -a      Include names starting with .
        -A      Like -a, but exclude . and ..
        -x      List by lines
        -d      List directory names, not contents
        -L      Follow symlinks
        -H      Follow symlinks on command line
        -R      Recurse
        -p      Append / to directory names
        -F      Append indicator (one of */=@|) to names
        -l      Long format
        -i      List inode numbers
        -n      List numeric UIDs and GIDs instead of names
        -s      List allocated blocks
        -lc     List ctime
        -lu     List atime
        --full-time     List full date/time
        -h      Human readable sizes (1K 243M 2G)
        -S      Sort by size
        -X      Sort by extension
        -v      Sort by version
        -t      Sort by mtime
        -tc     Sort by ctime
        -tu     Sort by atime
        -r      Reverse sort order
        -w N    Format N columns wide

List loaded kernel modules

lzcat [FILE]...

Decompress to stdout

lzma -d [-cfk] [FILE]...

Decompress FILEs (or stdin)

        -d      Decompress
        -c      Write to stdout
        -f      Force
        -k      Keep input files
        -t      Test integrity
lzop [-cfUvd123456789CF] [FILE]...

        -1..9   Compression level
        -d      Decompress
        -c      Write to stdout
        -f      Force
        -U      Delete input files
        -v      Verbose
        -F      Don't store or verify checksum
        -C      Also write checksum of compressed block
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 [-vS] { [-s] | [-df] }

        -v      Verbose
        -S      Log to syslog too
        -s      Scan /sys and populate /dev
        -d      Daemon, listen on netlink
        -f      Run in foreground

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

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_MS] [-t TIMEOUT_MS ] [-s SPEED] [-X] TTY

Copy bytes from stdin to TTY and from TTY to stdout

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

Run a script from a Makefile-like specification file

        -f FILE         Spec file (default Mimfile)
mkdir [-m MODE] [-p] DIRECTORY...


        -m MODE Mode
        -p      No error if exists; make parent directories as needed
mkdosfs [-v] [-n LABEL] BLOCKDEV [KBYTES]

Make a FAT32 filesystem

        -v      Verbose
        -n LBL  Volume label

        -b BLK_SIZE     Block size, bytes
        -F              Force
        -i RATIO        Max number of files is filesystem_size / RATIO
        -I BYTES        Inode size (min 128)
        -L LBL          Volume label
        -m PERCENT      Percent of blocks to reserve for admin
        -n              Dry run
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 MINOR must be omitted)
mkpasswd [-P FD] [-m TYPE] [-S SALT] [PASSWORD] [SALT]

Print crypt(3) hashed PASSWORD

        -P N    Read password from fd N
        -m TYPE des,md5,sha256/512 (default )
        -S SALT

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 [-adlpn0] [-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              NUL terminated output
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
        -t FSTYPE[,...] Filesystem type(s)
        -T FILE         Read FILE instead of /etc/fstab
        -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              Same as -r

There are filesystem-specific -o flags.


Control magnetic tape drive operation


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 [-finT] SOURCE DEST or: mv [-fin] SOURCE... { -t DIRECTORY | DIRECTORY }


        -f      Don't prompt before overwriting
        -i      Interactive, prompt before overwrite
        -n      Don't overwrite an existing file
        -T      Refuse to move if DEST is a directory
        -t DIR  Move all SOURCEs into DIR
nameif [-s] [-c FILE] [IFNAME HWADDR]...

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

        -c FILE Configuration file (default: /etc/mactab)
        -s      Log to syslog
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
nl [OPTIONS] [FILE]...

Write FILEs to standard output with line numbers added

        -b STYLE        Which lines to number - a: all, t: nonempty, n: none
        -i N            Line number increment
        -s STRING       Use STRING as line number separator
        -v N            Start from N
        -w N            Width of line numbers

Politely refuse a login

nproc [--all] [--ignore=N]

Print number of available CPUs

        --all           Number of installed CPUs
        --ignore=N      Exclude N CPUs

        -t PID          Target process to get namespaces from
        -m[FILE]        Enter mount namespace
        -u[FILE]        Enter UTS namespace (hostname etc)
        -i[FILE]        Enter System V IPC namespace
        -n[FILE]        Enter network namespace
        -p[FILE]        Enter pid namespace
        -U[FILE]        Enter user namespace
        -S UID          Set uid in entered namespace
        -G GID          Set gid in entered namespace
        --preserve-credentials  Don't touch uids or gids
        -r[DIR]         Set root directory
        -w[DIR]         Set working directory
        -F              Don't fork before exec'ing PROG
nslookup [-type=QUERY_TYPE] [-debug] HOST [DNS_SERVER]

Query DNS about HOST

QUERY_TYPE: soa,ns,a,aaaa,cname,mx,txt,ptr,srv,any

nuke DIR...

Remove DIRs

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

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
partprobe DEVICE...

Ask kernel to rescan partition table

paste [-d LIST] [-s] [FILE]...

Paste lines from each input file, separated with tab

        -d LIST Use delimiters from LIST, not tab
        -s      Serial: one file at a time
patch [-RNE] [-p N] [-i DIFF] [ORIGFILE [PATCHFILE]]

        -p N    Strip N leading components from file names
        -i DIFF Read DIFF instead of stdin
        -R      Reverse patch
        -N      Ignore already applied patches
        -E      Remove output files if they become empty
        --dry-run       Don't actually change files
pidof [NAME]...

List PIDs of all processes with names that match NAMEs



        -4,-6           Force IP or IPv6 name resolution
        -c CNT          Send only CNT pings
        -s SIZE         Send SIZE data bytes in packets (default 56)
        -i SECS         Interval
        -A              Ping as soon as reply is received
        -t TTL          Set TTL
        -I IFACE/IP     Source interface or IP address
        -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 display output at start/finish
        -p HEXBYTE      Payload pattern


        -c CNT          Send only CNT pings
        -s SIZE         Send SIZE data bytes in packets (default 56)
        -i SECS         Interval
        -A              Ping as soon as reply is received
        -I IFACE/IP     Source interface or IP address
        -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 display output at start/finish
        -p HEXBYTE      Payload pattern
pivot_root NEW_ROOT PUT_OLD

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

poweroff [-d DELAY] [-nf]

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

Show list of processes

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

Print the full filename of the current working directory

rdate [-s/-p] HOST

Set and print time from HOST using RFC 868

        -s      Only set system time
        -p      Only print 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...

Print absolute pathnames of FILEs

reboot [-d DELAY] [-nf]

Reboot the system

        -d SEC  Delay interval
        -n      Do not sync
        -f      Force (don't go through init)
renice [-n] PRIORITY [[-p|g|u] ID...]...

Change scheduling priority of a running process

        -n      Add PRIORITY to current nice value
                Without -n, nice value is set to PRIORITY
        -p      Process ids (default)
        -g      Process group ids
        -u      Process user names

Reset the screen


Restore system state from 'suspend-to-disk' data in BLOCKDEV

rev [FILE]...

Reverse lines of FILE

rm [-irf] FILE...

Remove (unlink) FILEs

        -i      Always prompt before removing
        -f      Never prompt
        -R,-r   Recurse
rmdir [-p] DIRECTORY...

Remove DIRECTORY if it is empty

        -p      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 [-ne] [-A inet[6]] [{add|del} [-net|-host] TARGET [netmask MASK] [gw GATEWAY] [metric N] [mss BYTES] [window BYTES] [reject] [IFACE]]

Show or edit kernel routing tables

        -n      Don't resolve names
        -e      Display other/more information
        -A inet[6]      Select address family
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-init [-d CAP,CAP...] [-n] [-c CONSOLE_DEV] 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
        -d CAPS Drop capabilities
        -n      Dry run
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 [-i[SFX]] [-nrE] [-f FILE]... [-e CMD]... [FILE]... or: sed [-i[SFX]] [-nrE] 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 write 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 [-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 }...

Modify kernel's scancode-to-keycode map, allowing unusual keyboards to generate usable keycodes.

SCANCODE is either xx or e0xx (hexadecimal), KEYCODE is decimal.


Run PROG with different privilege settings

-d,--dump Show current capabilities --nnp,--no-new-privs Ignore setuid/setgid bits and file capabilities --inh-caps CAP,CAP Set inheritable capabilities --ambient-caps CAP,CAP Set ambient capabilities

setsid [-c] PROG ARGS

Run PROG in a new session. PROG will have no controlling terminal and will not be affected by keyboard signals (^C etc).

        -c      Set controlling terminal to stdin
sh [-il] [-|+Cabefmnuvx] [-|+o OPT]... [-c 'SCRIPT' [ARG0 ARGS] | FILE ARGS | -s 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
sha3sum [-c[sw]] [-a BITS] [FILE]...

Print or check SHA3 checksums

        -c      Check sums against list in FILEs
        -s      Don't output anything, status code shows success
        -w      Warn about improperly formatted checksum lines
        -a BITS 224 (default), 256, 384, 512
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
shred [-fuz] [-n N] [-s SIZE] FILE...

Overwrite/delete FILEs

        -f      Chmod to ensure writability
        -s SIZE Size to write
        -n N    Overwrite N times (default 3)
        -z      Final overwrite with zeros
        -u      Remove file
shuf [-n NUM] [-o FILE] [-z] [FILE | -e [ARG...] | -i L-H]

Randomly permute lines

        -n NUM  Output at most NUM lines
        -o FILE Write to FILE, not standard output
        -z      NUL terminated output
        -e      Treat ARGs as lines
        -i L-H  Treat numbers L-H as 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 [-nrugMcszbdfiokt] [-o FILE] [-k START[.OFS][OPTS][,END[.OFS][OPTS]] [-t CHAR] [FILE]...

Sort lines of text

        -o FILE Output to FILE
        -c      Check whether input is sorted
        -b      Ignore leading blanks
        -f      Ignore case
        -i      Ignore unprintable characters
        -d      Dictionary order (blank or alphanumeric only)
        -n      Sort numbers
        -g      General numerical sort
        -M      Sort month
        -V      Sort version
        -t CHAR Field separator
        -k N[,M] Sort by Nth field
        -r      Reverse sort order
        -s      Stable (don't sort ties alphabetically)
        -u      Suppress duplicate lines
        -z      NUL terminated input and output
ssl_client [-e] -s FD [-r FD] [-n SNI]
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 USERNAME|UID Match only this user's processes
        -n NAME         Match processes with NAME
                        in comm field in /proc/PID/stat
        -x EXECUTABLE   Match processes with this command
                        in /proc/PID/cmdline
        -p FILE         Match a process with PID from FILE
        All specified conditions must match
-S only:
        -x EXECUTABLE   Program to run
        -a NAME         Zeroth argument
        -b              Background
        -N N            Change nice level
        -c USER[:[GRP]] Change user/group
        -m              Write PID to pidfile specified by -p
-K only:
        -s SIG          Signal to send
        -t              Match only, exit with 0 if found
        -o              Exit with status 0 if nothing is done
        -v              Verbose
        -q              Quiet
stat [-ltf] [-c FMT] FILE...

Display file (default) or filesystem status

        -c FMT  Use the specified format
        -f      Display filesystem status
        -L      Follow links
        -t      Terse display

FMT sequences for files:

 %a     Access rights in octal
 %A     Access rights in human readable form
 %b     Number of blocks allocated (see %B)
 %B     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
 %G     Group name
 %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
 %U     User name
 %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

FMT sequences for file systems:

 %a     Free blocks available to non-superuser
 %b     Total data blocks
 %c     Total file nodes
 %d     Free file nodes
 %f     Free blocks
 %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 [-fo] [-t o|d|x] [-n LEN] [FILE]...

Display printable strings in a binary file

        -f              Precede strings with filenames
        -o              Precede strings with octal offsets
        -t o|d|x        Precede strings with offsets in base 8/10/16
        -n LEN          At least LEN characters form a string (default 4)
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
svc [-udopchaitkx] SERVICE_DIR...

Control services monitored by runsv supervisor

        -u      If service is not running, start it; restart if it stops
        -d      If service is running, send TERM+CONT signals; do not restart it
        -o      Once: if service is not running, start it; do not restart it
        -pchaitk Send STOP, CONT, HUP, ALRM, INT, TERM, KILL signal to service
        -x      Exit: runsv will exit as soon as the service is down

Check whether runsv supervisor is running. Exit code is 0 if it does, 100 if it does not, 111 (with error message) if SERVICE_DIR does not exist.

swapoff [-a] [DEVICE]

Stop swapping on DEVICE

        -a      Stop swapping on all swap devices
swapon [-a] [-e] [-d[POL]] [DEVICE]

Start swapping on DEVICE

        -a      Start swapping on all swap devices
        -d[POL] Discard blocks at swapon (POL=once),
                as freed (POL=pages), or both (POL omitted)
        -e      Silently skip devices that do not exist

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
sync [-df] [FILE]...

Write all buffered blocks (in FILEs) to disk -d Avoid syncing metadata -f Sync filesystems underlying FILEs

sysctl [-enq] { -a | -p [FILE]... | [-w] [KEY[=VALUE]]... }

Show/set kernel parameters

        -e      Don't warn about unknown keys
        -n      Don't show key names
        -q      Quiet
        -a      Show all values
        -p      Set values from FILEs (default /etc/sysctl.conf)
        -w      Set values
syslogd [OPTIONS]

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

        -n              Run in foreground
        -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)
        -O FILE         Log to FILE (default: /var/log/messages, stdout if -)
        -l N            Log only messages more urgent than prio N (1-8)
        -S              Smaller output
        -t              Strip client-generated timestamps
tac [FILE]...

Concatenate FILEs and print them in reverse

tail [OPTIONS] [FILE]...

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

        -c [+]N[bkm]    Print last N bytes
        -n N[bkm]       Print last N lines
        -n +N[bkm]      Start on Nth line and print the rest
                        (b:*512 k:*1024 m:*1024^2)
        -q              Never print headers
        -v              Always print headers
        -f              Print data as file grows
        -F              Same as -f, but keep retrying
        -s SECONDS      Wait SECONDS between reads with -f
tar c|x|t [-ZzJjahmvokO] [-f TARFILE] [-C DIR] [FILE]...

Create, extract, or list files from a tar file

        c       Create
        x       Extract
        t       List
        -f FILE Name of TARFILE ('-' for stdin/out)
        -C DIR  Change to DIR before operation
        -v      Verbose
        -O      Extract to stdout
        -m      Don't restore mtime
        -o      Don't restore user:group
        -k      Don't replace existing files
        -Z      (De)compress using compress
        -z      (De)compress using gzip
        -J      (De)compress using xz
        -j      (De)compress using bzip2
        --lzma  (De)compress using lzma
        -a      (De)compress based on extension
        -h      Follow symlinks
        --overwrite             Replace existing files
        --strip-components NUM  NUM of leading components to strip
        --no-recursion          Don't descend in directories
        --numeric-owner         Use numeric user:group
        --no-same-permissions   Don't restore access permissions
        --to-command COMMAND    Pipe files to COMMAND
taskset [-ap] [HEXMASK | -c LIST] { PID | PROG ARGS }

Set or get CPU affinity

        -p      Operate on PID
        -a      Operate on all threads
        -c      Affinity is a list, not mask
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

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 in bytes
time [-vpa] [-o FILE] PROG ARGS

Run PROG, display resource usage when it exits

        -v      Verbose
        -p      POSIX output format
        -f FMT  Custom format
        -o FILE Write result to FILE
        -a      Append (else overwrite)
timeout [-s SIG] [-k KILL_SECS] SECS PROG ARGS

Run PROG. Send SIG to it if it is not gone in SECS seconds. Default SIG: TERM.If it still exists in KILL_SECS seconds, send KILL.

top [-bH] [-n COUNT] [-d SECONDS]

Show a view of process activity in real time. Read the status of all processes from /proc each SECONDS and show 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 SEC  Delay between updates
        -H      Show threads
touch [-cham] [-d DATE] [-t DATE] [-r FILE] FILE...

Update mtime of FILEs

        -c      Don't create files
        -h      Don't follow links
        -a      Change only atime
        -m      Change only mtime
        -d DT   Date/time to use
        -t DT   Date/time to use
        -r FILE Use FILE's date/time
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 [-46Flnrv] [-f 1ST_TTL] [-m MAXTTL] [-q PROBES] [-p PORT] [-t TOS] [-w WAIT_SEC] [-s SRC_IP] [-i IFACE] [-z PAUSE_MSEC] HOST [BYTES]

Trace the route to HOST

        -4,-6   Force IP or IPv6 name resolution
        -F      Set don't fragment bit
        -l      Display TTL value of the returned packet
        -n      Print numeric addresses
        -r      Bypass routing tables, send directly to HOST
        -v      Verbose
        -f N    First number of hops (default 1)
        -m N    Max number of hops
        -q N    Number of probes per hop (default 3)
        -p N    Base UDP port number used in probes
                (default 33434)
        -s IP   Source address
        -i IFACE Source interface
        -t N    Type-of-service in probe packets (default 0)
        -w SEC  Wait for a response (default 3)
        -z MSEC Wait before each send
traceroute6 [-nrv] [-f 1ST_TTL] [-m MAXTTL] [-q PROBES] [-p PORT] [-t TOS] [-w WAIT_SEC] [-s SRC_IP] [-i IFACE] [-z PAUSE_MSEC] HOST [BYTES]

Trace the route to HOST

        -n      Print numeric addresses
        -r      Bypass routing tables, send directly to HOST
        -v      Verbose
        -f N    First number of hops (default 1)
        -m N    Max number of hops
        -q N    Number of probes per hop (default 3)
        -p N    Base UDP port number used in probes
                (default 33434)
        -s IP   Source address
        -i IFACE Source interface
        -t N    Type-of-service in probe packets (default 0)
        -w SEC  Wait for a response (default 3)
        -z MSEC Wait before each send
truncate [-c] -s SIZE FILE...

Truncate FILEs to SIZE

        -c      Do not create files
        -s SIZE
ts [-is] [STRFTIME]

Pipe stdin to stdout, add timestamp to each line

        -s      Time since start
        -i      Time since previous line
tty [-s]

Print file name of stdin's terminal

        -s      Print nothing, only return exit status

Rename UBI volumes on UBI_DEVICE

udhcpc [-fbqRB] [-a[MSEC]] [-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 IFACE        Interface to use (default eth0)
        -s PROG         Run PROG at DHCP events (default /etc/udhcpc/default.script)
        -p FILE         Create pidfile
        -B              Request broadcast replies
        -t N            Send up to N discover packets (default 3)
        -T SEC          Pause between packets (default 3)
        -A SEC          Wait if lease is not obtained (default 20)
        -b              Background if lease is not obtained
        -n              Exit if lease is not obtained
        -q              Exit after obtaining lease
        -R              Release IP on exit
        -f              Run in foreground
        -S              Log to syslog too
        -a[MSEC]        Validate offered address with ARP ping
        -r IP           Request this IP address
        -o              Don't request any options (unless -O is given)
        -O 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)
                        -x 14:'"dumpfile"' - option 14 (shell-quoted)
        -F NAME         Ask server to update DNS mapping for NAME
        -V VENDOR       Vendor identifier (default 'udhcp VERSION')
        -C              Don't send MAC as client identifier
        USR1    Renew lease
        USR2    Release lease
udhcpd [-fS] [-I ADDR] [-a MSEC] [CONFFILE]

DHCP server

        -f      Run in foreground
        -S      Log to syslog too
        -I ADDR Local address
        -a MSEC Timeout for ARP ping (default 2000)
        USR1    Update lease file
uevent [PROG ARGS]

uevent runs PROG for every netlink notification. PROG's environment contains data passed from the kernel. Typical usage (daemon for dynamic device node creation): # uevent mdev & mdev -s


Unmount filesystems

        -a      Unmount all filesystems
        -r      Remount devices read-only if mount is busy
        -l      Lazy umount (detach filesystem)
        -f      Force umount (i.e., unreachable NFS server)
        -d      Free loop device if it has been used
        -t FSTYPE[,...] Unmount only these filesystem type(s)
uname [-amnrspvio]

Print system information

        -a      Print all
        -m      Machine (hardware) type
        -n      Hostname
        -r      Kernel release
        -s      Kernel name (default)
        -p      Processor type
        -v      Kernel version
        -i      Hardware platform
        -o      OS name
uncompress [-cf] [FILE]...

Decompress FILEs (or stdin)

        -c      Write to stdout
        -f      Overwrite
unexpand [-fa][-t N] [FILE]...

Convert spaces to tabs, writing to stdout

        -a      Convert all blanks
        -f      Convert only leading blanks
        -t N    Tabstops every N chars
uniq [-cduiz] [-f,s,w N] [FILE [OUTFILE]]

Discard duplicate lines

        -c      Prefix lines by the number of occurrences
        -d      Only print duplicate lines
        -u      Only print unique lines
        -i      Ignore case
        -z      NUL terminated output
        -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 stdin/stdout.

        -u      dos2unix
        -d      unix2dos
unlink FILE

Delete FILE by calling unlink()

unlzma [-cfk] [FILE]...

Decompress FILEs (or stdin)

        -c      Write to stdout
        -f      Force
        -k      Keep input files
        -t      Test integrity

        -m,--mount[=FILE]       Unshare mount namespace
        -u,--uts[=FILE]         Unshare UTS namespace (hostname etc.)
        -i,--ipc[=FILE]         Unshare System V IPC namespace
        -n,--net[=FILE]         Unshare network namespace
        -p,--pid[=FILE]         Unshare PID namespace
        -U,--user[=FILE]        Unshare user namespace
        -f                      Fork before execing PROG
        -r                      Map current user to root (implies -U)
        --mount-proc[=DIR]      Mount /proc filesystem first (implies -m)
        --propagation slave|shared|private|unchanged
                                Modify mount propagation in mount namespace
        --setgroups allow|deny  Control the setgroups syscall in user namespaces
unxz [-cfk] [FILE]...

Decompress FILEs (or stdin)

        -c      Write to stdout
        -f      Force
        -k      Keep input files
        -t      Test integrity
unzip [-lnojpq] 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
        -j      Do not restore paths
        -p      Write to stdout
        -t      Test
        -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

        add IFACE VLAN_ID
        rem VLAN_NAME
        set_flag IFACE 0|1 VLAN_QOS
        set_egress_map VLAN_NAME SKB_PRIO VLAN_QOS
        set_ingress_map VLAN_NAME SKB_PRIO VLAN_QOS
        set_name_type NAME_TYPE
vi [-c CMD] [-R] [-H] [FILE]...


        -c CMD  Initial command to run ($EXINIT and ~/.exrc also available)
        -R      Read-only
        -H      List available features

Show who is logged on

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

Run PROG periodically

        -n SEC  Period (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 [-cmlwL] [FILE]...

Count lines, words, and bytes for FILEs (or stdin)

        -c      Count bytes
        -m      Count characters
        -l      Count newlines
        -w      Count words
        -L      Print longest line length
wget [-cqS] [--spider] [-O FILE] [-o LOGFILE] [--header STR] [--post-data STR | --post-file FILE] [-Y on/off] [--no-check-certificate] [-P DIR] [-U AGENT] URL...

Retrieve files via HTTP or FTP

        --spider        Only check URL existence: $? is 0 if exists
        --header STR    Add STR (of form 'header: value') to headers
        --post-data STR Send STR using POST method
        --post-file FILE        Send FILE using POST method
        --no-check-certificate  Don't validate the server's certificate
        -c              Continue retrieval of aborted transfer
        -q              Quiet
        -P DIR          Save to DIR (default .)
        -S              Show server response
        -O FILE         Save to FILE ('-' for stdout)
        -o LOGFILE      Log messages to FILE
        -U STR          Use STR for User-Agent header
        -Y on/off       Use proxy
which [-a] COMMAND...


        -a      Show all matches
who [-aH]

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

        -0      NUL terminated input
        -a FILE Read from FILE instead of stdin
        -r      Don't run command if input is empty
        -t      Print the command on stderr before execution
        -p      Ask user whether to run each command
        -E STR,-e[STR]  STR stops input processing
        -I STR  Replace STR within PROG ARGS with input line
        -n N    Pass no more than N args to PROG
        -s N    Pass command line of no more than N bytes
        -P N    Run up to N PROGs in parallel
        -x      Exit if size is exceeded
xxd [-pri] [-g N] [-c N] [-n LEN] [-s OFS] [-o OFS] [FILE]

Hex dump FILE (or stdin)

        -g N            Bytes per group
        -c N            Bytes per line
        -p              Show only hex bytes, assumes -c30
        -i              C include file style
        -l LENGTH       Show only first LENGTH bytes
        -s OFFSET       Skip OFFSET bytes
        -o OFFSET       Add OFFSET to displayed offset
        -r              Reverse (with -p, assumes no offsets in input)
xz -d [-cfk] [FILE]...

Decompress FILEs (or stdin)

        -d      Decompress
        -c      Write to stdout
        -f      Force
        -k      Keep input files
        -t      Test integrity
xzcat [FILE]...

Decompress to stdout

yes [STRING]

Repeatedly print 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 <>


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 <>


Erik Andersen <>

    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 <>

    rpm2cpio, unzip, get_header_cpio, read_gz interface, rpm

Jeff Angielski <>

    ftpput, ftpget

Edward Betts <>

    expr, hostid, logname, whoami

John Beppu <>

    du, nslookup, sort

Brian Candler <>


Randolph Chung <>

    fbset, ping, hostname

Dave Cinege <>

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

Jordan Crouse <>


Magnus Damm <>

    tftp client insmod powerpc support

Larry Doolittle <>

    pristine source directory compilation, lots of patches and fixes.

Glenn Engel <>


Gennady Feldman <>

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

Karl M. Hegbloom <>

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

Daniel Jacobowitz <>


Matt Kraai <>

    documentation, bugfixes, test suite

Stephan Linz <>

    ipcalc, Red Hat equivalence

John Lombardo <>


Glenn McGrath <>

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

Manuel Novoa III <>

    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 <>

    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 <>

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

Tim Riker <>

    bug fixes, member of fan club

Kent Robotti <>

    reset, tons and tons of bug reports and patches.

Chip Rosenthal <>, <>

    wget - Contributed by permission of Covad Communications

Pavel Roskin <>

    Lots of bugs fixes and patches.

Gyepi Sam <>

    Remote logging feature for syslogd

Linus Torvalds <>

    mkswap, fsck.minix, mkfs.minix

Mark Whitley <>

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

Charles P. Wright <>

    gzip, mini-netcat(nc)

Enrique Zanardi <>

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

Tito Ragusa <>

    devfsd and size optimizations in strings, openvt and deallocvt.

Paul Fox <>

    vi editing mode for ash, various other patches/fixes

Roberto A. Foglietta <>

    port: dnsd

Bernhard Reutner-Fischer <>


Mike Frysinger <>

    initial e2fsprogs, printenv, setarch, sum, misc

Jie Zhang <>

    fixed two bugs in msh and hush (exitcode of killed processes)
2023-04-23 version 1.35.0