BusyBox - The Swiss Army Knife of Embedded Linux
BusyBox <function> [arguments...] # or
<function> [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
./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 commands 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 defined functions include:
[, [[, addgroup, adduser, adjtimex, ar, arp, arping, ash, awk,
basename, bbconfig, bbsh, bunzip2, busybox, bzcat, cal, cat,
catv, chattr, chcon, chgrp, chmod, chown, chpasswd, chpst,
chroot, chrt, chvt, cksum, clear, cmp, comm, cp, cpio, crond,
crontab, cryptpw, cut, date, dc, dd, deallocvt, delgroup,
deluser, devfsd, df, dhcprelay, diff, dirname, dmesg, dnsd,
dos2unix, dpkg, dpkg_deb, du, dumpkmap, dumpleases, e2fsck, echo,
ed, eject, env, envdir, envuidgid, ether_wake, expand, expr,
fakeidentd, false, fbset, fdflush, fdformat, fdisk, find, fold,
free, freeramdisk, fsck, fsck_minix, ftpget, ftpput, fuser,
getenforce, getopt, getsebool, getty, grep, gunzip, gzip, halt,
hdparm, head, hexdump, hostid, hostname, httpd, hwclock, id,
ifconfig, ifdown, ifup, inetd, init, insmod, install, ip, ipaddr,
ipcalc, ipcrm, ipcs, iplink, iproute, iprule, iptunnel, kill,
killall, killall5, klogd, lash, last, length, less, ln,
load_policy, loadfont, loadkmap, logger, login, logname, logread,
losetup, ls, lsattr, lsmod, lzmacat, makedevs, matchpathcon,
md5sum, mdev, mesg, microcom, mkdir, mke2fs, mkfifo, mkfs_minix,
mknod, mkswap, mktemp, modprobe, more, mount, mountpoint, mt, mv,
nameif, nc, netstat, nice, nmeter, nohup, nslookup, od, openvt,
passwd, patch, pgrep, pidof, ping, ping6, pivot_root, pkill,
poweroff, printenv, printf, ps, pscan, pwd, raidautorun, rdate,
readahead, readlink, readprofile, realpath, reboot, renice,
reset, resize, restorecon, rm, rmdir, rmmod, route, rpm,
rpm2cpio, run_parts, runcon, runlevel, runsv, runsvdir, rx, sed,
selinuxenabled, seq, setarch, setconsole, setenforce, setfiles,
setkeycodes, setlogcons, setsid, setuidgid, sha1sum, slattach,
sleep, softlimit, sort, split, start_stop_daemon, stat, strings,
stty, su, sulogin, sum, sv, svlogd, swapoff, swapon, switch_root,
sync, sysctl, syslogd, tail, tar, taskset, tcpsvd, tee, telnet,
telnetd, test, tftp, time, top, touch, tr, traceroute, true, tty,
ttysize, tune2fs, udhcpc, udhcpd, udpsvd, umount, uname,
uncompress, unexpand, uniq, unix2dos, unlzma, unzip, uptime,
usleep, uudecode, uuencode, vconfig, vi, vlock, watch, watchdog,
wc, wget, which, who, whoami, xargs, yes, zcat, zcip
Add a group to the system or add an user to a group
Options:
-g GID Group id
Add a user to the system
Options:
-h DIR Home directory
-g GECOS GECOS field
-s SHELL Login shell
-G GROUP Add user to existing group
-S Create a system user (ignored)
-D Do not assign a password
-H Do not create home directory
Read and optionally set system timebase parameters. See adjtimex(2).
Options:
-q Quiet
-o offset Time offset, microseconds
-f frequency Frequency adjust, integer kernel units (65536 is 1ppm)
(positive values make clock run faster)
-t tick Microseconds per tick, usually 10000
-p timeconstant
Extract or list FILES from an ar archive
Options:
-o Preserve original dates
-p Extract to stdout
-t List
-x Extract
-v Verbose
| arp | |
| [-vn] | [-H type] [-i if] -a [hostname] |
| [-v] | [-i if] -d hostname [pub] |
| [-v] | [-H type] [-i if] -s hostname hw_addr [temp] |
| [-v] | [-H type] [-i if] -s hostname hw_addr [netmask nm] pub |
| [-v] | [-H type] [-i if] -Ds hostname ifa [netmask nm] pub |
Manipulate the system ARP cache
Options:
-a Display (all) hosts
-s Set a new ARP entry
-d Delete a specified entry
-v Verbose
-n Don't resolve names
-i if Network interface (e.g. eth0)
-D Read <hwaddr> from given device
-A, -p Protocol family
-H hwtype Hardware address type
Ping hosts by ARP requests/replies
Options:
-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 neighbours
-A ARP answer mode, update your neighbours
-c count Stop after sending count ARP request packets
-w timeout Time to wait for ARP reply, in seconds
-I device Outgoing interface name, default is eth0
-s sender Set specific sender IP address
target Target IP address of ARP request
The ash shell (command interpreter)
Options:
-v var=val Set variable
-F sep Use sep as field separator
-f filename Read program from file
Strip directory path and suffixes from FILE. If specified, also remove any trailing SUFFIX.
Example:
$ basename /usr/local/bin/foo
foo
$ basename /usr/local/bin/
bin
$ basename /foo/bar.txt .txt
bar
Print the config file which built busybox
The bbsh shell (command interpreter)
Uncompress FILE (or standard input if FILE is '-' or omitted)
Options:
-c Write output to standard output
-f Force
Hello world!
Uncompress to stdout
Display a calendar
Options:
-j Use julian dates
-y Display the entire year
Concatenate FILE(s) and print them to stdout
Options:
-u Use unbuffered i/o (ignored)
Example:
$ cat /proc/uptime
110716.72 17.67
Display nonprinting characters as ^x or M-x
Options:
-e End each line with $
-t Show tabs as ^I
-v Don't use ^x or M-x escapes
Change file attributes on an ext2 fs
Modifiers:
- Remove attributes
+ Add attributes
= Set attributes
Attributes:
A Don't track atime
a Append mode only
c Enable compress
D Write dir contents synchronously
d Do not backup with dump
i Cannot be modified (immutable)
j Write all data to journal first
s Zero disk storage when deleted
S Write file contents synchronously
t Disable tail-merging of partial blocks with other files
u Allow file to be undeleted
Options:
-R Recursively list subdirectories
-v Set the file's version/generation number
| chcon [OPTIONS] CONTEXT FILE... | |
| chcon [OPTIONS] [-u USER] [-r ROLE] [-l RANGE] [-t TYPE] FILE... | |
| chcon [OPTIONS] --reference=RFILE FILE... |
Change the security context of each FILE to CONTEXT
-v, --verbose Verbose
-c, --changes Report changes made
-h, --no-dereference Affect symlinks instead of their targets
-f, --silent, --quiet Suppress most error messages
--reference=RFILE Use RFILE's group instead of using a CONTEXT value
-u, --user=USER Set user USER in the target security context
-r, --role=ROLE Set role ROLE in the target security context
-t, --type=TYPE Set type TYPE in the target security context
-l, --range=RANGE Set range RANGE in the target security context
-R, --recursive Recurse subdirectories
Change the group membership of each FILE to GROUP
Options:
-R Recurse directories
-h Affect symlinks instead of symlink targets
-L Traverse all symlinks to directories
-H Traverse symlinks on command line only
-P Do not traverse symlinks (default)
-c List changed files
-v Verbose
-f Hide errors
Example:
$ ls -l /tmp/foo
-r--r--r-- 1 andersen andersen 0 Apr 12 18:25 /tmp/foo
$ chgrp root /tmp/foo
$ ls -l /tmp/foo
-r--r--r-- 1 andersen root 0 Apr 12 18:25 /tmp/foo
Each MODE is one or more of the letters ugoa, one of the symbols +-= and one or more of the letters rwxst
Options:
-R Recurse directories
-c List changed files
-v List all files
-f Hide errors
Example:
$ ls -l /tmp/foo
-rw-rw-r-- 1 root root 0 Apr 12 18:25 /tmp/foo
$ chmod u+x /tmp/foo
$ ls -l /tmp/foo
-rwxrw-r-- 1 root root 0 Apr 12 18:25 /tmp/foo*
$ chmod 444 /tmp/foo
$ ls -l /tmp/foo
-r--r--r-- 1 root root 0 Apr 12 18:25 /tmp/foo
Change the owner and/or group of each FILE to OWNER and/or GROUP
Options:
-R Recurse directories
-h Affect symlinks instead of symlink targets
-L Traverse all symlinks to directories
-H Traverse symlinks on command line only
-P Do not traverse symlinks (default)
-c List changed files
-v List all files
-f Hide errors
Example:
$ ls -l /tmp/foo
-r--r--r-- 1 andersen andersen 0 Apr 12 18:25 /tmp/foo
$ chown root /tmp/foo
$ ls -l /tmp/foo
-r--r--r-- 1 root andersen 0 Apr 12 18:25 /tmp/foo
$ chown root.root /tmp/foo
ls -l /tmp/foo
-r--r--r-- 1 root root 0 Apr 12 18:25 /tmp/foo
Read user:password information from stdin and update /etc/passwd accordingly.
Options:
-e, --encrypt Supplied passwords are in encrypted form
-m, --md5 Use MD5 encryption instead of DES
Change the process state and run specified program
Options:
-u user[:grp] Set uid and gid
-U user[:grp] Set environment variables UID and GID
-e dir Set environment variables as specified by files
in the directory: file=1st_line_of_file
-/ dir Chroot to dir
-n inc Add inc to nice value
-m bytes Limit data segment, stack segment, locked physical pages,
and total of all segment per process to bytes bytes each
-d bytes Limit data segment
-o n Limit the number of open file descriptors per process to n
-p n Limit number of processes per uid to n
-f bytes Limit output file size to bytes bytes
-c bytes Limit core file size to bytes bytes
-v Verbose
-P Run prog in a new process group
-0 Close standard input
-1 Close standard output
-2 Close standard error
Run COMMAND with root directory set to NEWROOT
Example:
$ ls -l /bin/ls
lrwxrwxrwx 1 root root 12 Apr 13 00:46 /bin/ls -> /BusyBox
# mount /dev/hdc1 /mnt -t minix
# chroot /mnt
# ls -l /bin/ls
-rwxr-xr-x 1 root root 40816 Feb 5 07:45 /bin/ls*
manipulate real-time attributes of a process
Options:
-p operate on pid
-r set scheduling policy to SCHED_RR
-f set scheduling policy to SCHED_FIFO
-o set scheduling policy to SCHED_OTHER
-m show min and max priorities
Example:
$ chrt -r 4 sleep 900; x=$!
$ chrt -f -p 3 $x
You need CAP_SYS_NICE privileges to set scheduling attributes of a process
Change the foreground virtual terminal to /dev/ttyN
Calculate the CRC32 checksums of FILES
Clear screen
Compares FILE1 vs stdin if FILE2 is not specified
Options:
-l Write the byte numbers (decimal) and values (octal)
for all differing bytes
-s Quiet
Compare FILE1 to FILE2, or to stdin if - is specified
Options:
-1 Suppress lines unique to FILE1
-2 Suppress lines unique to FILE2
-3 Suppress lines common to both files
Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY
Options:
-a Same as -dpR
-c Preserves security context
-d,-P Preserve links
-H,-L Dereference all symlinks (default)
-p Preserve file attributes if possible
-f Force overwrite
-i Prompt before overwrite
-R,-r Recurse directories
-l,-s Create (sym)links
Extract or list files from a cpio archive Main operation mode:
d Make leading directories
i Extract
m Preserve mtime
t List
v Verbose
u Unconditional overwrite
F Input from file
-d [#] -l [#] -S -L logfile -f -b -c dir
-d num Debug level
-l num Log level (8 - default)
-S Log to syslogd (default)
-L file Log to file
-f Run in foreground
-b Run in background (default)
-c dir Working dir
file [opts] Replace crontab from file
- [opts] Replace crontab from stdin
-u user User
-l [user] List crontab for user
-e [user] Edit crontab for user
-d [user] Delete crontab for user
-c dir Crontab directory
Outputs crypted string. If string isn't supplied on cmdline, reads it from stdin.
Options:
-a Algorithm to use (default: md5)
Print selected fields from each input FILE to standard output
Options:
-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
Example:
$ echo "Hello world" | cut -f 1 -d ' '
Hello
$ echo "Hello world" | cut -f 2 -d ' '
world
Display current time in the given FORMAT, or set system date
Options:
-R Outputs RFC-822 compliant date string
-d STRING Displays time described by STRING, not 'now'
-I[TIMESPEC] Outputs an ISO-8601 compliant date/time string
TIMESPEC='date' (or missing) for date only,
'hours', 'minutes', or 'seconds' for date and
time to the indicated precision
-D hint Use 'hint' as date format, via strptime()
-s STRING Sets time described by STRING
-r FILE Displays the last modification time of FILE
-u Prints or sets Coordinated Universal Time
Example:
$ date
Wed Apr 12 18:52:41 MDT 2000
This is a Tiny RPN calculator that understands the following operations: +, add, -, sub, *, mul, /, div, %, mod, **, exp, and, or, not, eor. For example: 'dc 2 2 add' -> 4, and 'dc 8 8 \* 2 2 + /' -> 16.
Options: p - Prints the value on the top of the stack, without altering the stack f - Prints the entire contents of the stack without altering anything o - Pops the value off the top of the stack and uses it to set the output radix
Only 10 and 16 are supported
Example:
$ dc 2 2 + p
4
$ dc 8 8 \* 2 2 + / p
16
$ dc 0 1 and p
0
$ dc 0 1 or p
1
$ echo 72 9 div 8 mul p | dc
64
| dd [if=FILE] [of=FILE] [ibs=N] [obs=N] [bs=N] [count=N] [skip=N] | |
| [seek=N] [conv=notrunc|noerror|sync] |
Copy a file with converting and formatting
Options:
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
Numbers may be suffixed by c (x1), w (x2), b (x512), kD (x1000), k (x1024), MD (x1000000), M (x1048576), GD (x1000000000) or G (x1073741824)
Example:
$ dd if=/dev/zero of=/dev/ram1 bs=1M count=4
4+0 records in
4+0 records out
Deallocate unused virtual terminal /dev/ttyN
Delete group GROUP from the system or user USER from group GROUP
Delete user USER from the system
Manage devfs permissions and old device name symlinks
Options:
mntpnt The mount point where devfs is mounted
-v Print the protocol version numbers for devfsd
and the kernel-side protocol version and exit
-fg Run in foreground
-np Exit after parsing the configuration file
and processing synthetic REGISTER events,
do not poll for events
Print the filesystem space used and space available
Options control size display:
-h Human readable (e.g. 1K 243M 2G)
-m 1024*1024 blocks
-k 1024 blocks
Example:
$ df
Filesystem 1k-blocks Used Available Use% Mounted on
/dev/sda3 8690864 8553540 137324 98% /
/dev/sda1 64216 36364 27852 57% /boot
$ df /dev/sda3
Filesystem 1k-blocks Used Available Use% Mounted on
/dev/sda3 8690864 8553540 137324 98% /
Relay dhcp requests from client devices to server device
Compare files line by line and output the differences between them. This diff implementation only supports unified diffs.
Options:
-a Treat all files as text
-b Ignore changes in the amount of whitespace
-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 Recursively compare subdirectories
-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
Strip non-directory suffix from FILENAME
Example:
$ dirname /tmp/foo
/tmp
$ dirname /tmp/foo/
/tmp
Print or control the kernel ring buffer
Options:
-c Clears the ring buffer's contents after printing
-n LEVEL Sets console logging level
-s SIZE Use a buffer of size SIZE
Small and static DNS server daemon
Options:
-c Config filename
-t TTL in seconds
-p Listening port
-i Listening ip (default all)
-d Daemonize
Convert FILE from dos format to unix format. When no option is given, the input is converted to the opposite output format. When no file is given, use stdin for input and stdout for output.
Options:
-u Output will be in UNIX format
-d Output will be in DOS format
Install, remove and manage Debian packages
Options:
-i Install the package
-l List of installed packages
-C Configure an unpackaged package
-F depends Ignore dependency problems
-P Purge all files of a package
-r Remove all but the configuration files for a package
-u Unpack a package, but don't configure it
Perform actions on Debian packages (.debs)
Options:
-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
Example:
$ dpkg-deb -X ./busybox_0.48-1_i386.deb /tmp
Summarize disk space used for each FILE and/or directory. Disk space is printed in units of 1024 bytes.
Options:
-a Show sizes of files in addition to directories
-H Follow symlinks that are FILE command line args
-L Follow all symlinks encountered
-d N Limit output to directories (and files with -a) of depth < N
-c Output a 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 Print sizes in human readable format (e.g., 1K 243M 2G )
-m Print sizes in megabytes
-k Print sizes in kilobytes(default)
Example:
$ du
16 ./CVS
12 ./kernel-patches/CVS
80 ./kernel-patches
12 ./tests/CVS
36 ./tests
12 ./scripts/CVS
16 ./scripts
12 ./docs/CVS
104 ./docs
2417 .
Print out a binary keyboard translation table to standard output
Example:
$ dumpkmap > keymap
Display DHCP leases granted by udhcpd
Options:
-f, --file=FILENAME Leases file to load
-r, --remaining Interpret lease times as time remaining
-a, --absolute Interpret lease times as expire time
Check ext2/ext3 file system
Options:
-p Automatic repair (no questions)
-n Make no changes to the filesystem
-y Assume 'yes' to all questions
-c Check for bad blocks and add them to the badblock list
-f Force checking even if filesystem is marked clean
-v Verbose
-b superblock Use alternative superblock
-B blocksize Force blocksize when looking for superblock
-j journal Set location of the external journal
-l file Add to badblocks list
-L file Set badblocks list
Print the specified ARGs to stdout
Options:
-n Suppress trailing newline
-e Interpret backslash-escaped characters (i.e., \t=tab)
-E Disable interpretation of backslash-escaped characters
Example:
$ echo "Erik is cool"
Erik is cool
$ echo -e "Erik\nis\ncool"
Erik
is
cool
$ echo "Erik\nis\ncool"
Erik\nis\ncool
Eject specified DEVICE (or default /dev/cdrom)
Options:
-t Close tray
-T Open/close tray (toggle)
Print the current environment or run a program after setting up the specified environment
Options:
-, -i Start with an empty environment
-u Remove variable from the environment
Set various environment variables as specified by files in the directory dir, then run prog
Set $UID to account's uid and $GID to account's gid, then run prog
Send a magic packet to wake up sleeping machines. MAC must be a station address (00:11:22:33:44:55) or a hostname with a known 'ethers' entry.
Options:
-b Send wake-up packet to the broadcast address
-i iface Use interface ifname instead of the default "eth0"
-p pass Append the four or six byte password PW to the packet
Convert tabs to spaces, writing to standard output.
Options:
-i,--initial Do not convert tabs after non blanks
-t,--tabs=N Tabstops every N chars
Print the value of EXPRESSION to standard output.
EXPRESSION may be:
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 ARG1 is less than ARG2
ARG1 <= ARG2 ARG1 is less than or equal to ARG2
ARG1 = ARG2 ARG1 is equal to ARG2
ARG1 != ARG2 ARG1 is unequal to ARG2
ARG1 >= ARG2 ARG1 is greater than or equal to ARG2
ARG1 > ARG2 ARG1 is greater than ARG2
ARG1 + ARG2 Sum of ARG1 and ARG2
ARG1 - ARG2 Difference of ARG1 and ARG2
ARG1 * ARG2 Product of ARG1 and ARG2
ARG1 / ARG2 Quotient of ARG1 divided by ARG2
ARG1 % ARG2 Remainder of ARG1 divided by ARG2
STRING : REGEXP Anchored pattern match of REGEXP in STRING
match STRING REGEXP Same as STRING : REGEXP
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 '/'
(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.
Provide fake ident (auth) service
Options:
-f Run in foreground
-i Inetd mode
-w Inetd 'wait' mode
-b ADDR Bind to specified address
STRING Ident answer string (default is 'nobody')
Return an exit code of FALSE (1)
Example:
$ false
$ echo $?
1
Show and modify frame buffer settings
Example:
$ fbset
mode "1024x768-76"
# D: 78.653 MHz, H: 59.949 kHz, V: 75.694 Hz
geometry 1024 768 1024 768 16
timings 12714 128 32 16 4 128 4
accel false
rgba 5/11,6/5,5/0,0/0
endmode
Force floppy disk drive to detect disk change
Format floppy disk
Options:
-n Don't verify after format
Change partition table
Options:
-l List partition table(s)
-u Give Start and End in sector (instead of cylinder) units
-s PARTITION Give partition size(s) in blocks
-b 2048 (for certain MO disks) use 2048-byte sectors
-C CYLINDERS Set the number of cylinders
-H HEADS Set the number of heads
-S SECTORS Set the number of sectors
-v Give fdisk version
Search for files in a directory hierarchy. The default PATH is the current directory, default EXPRESSION is '-print'
EXPRESSION may consist of:
-follow Dereference symlinks
-xdev Don't descend directories on other filesystems
-maxdepth N Descend at most N levels. -maxdepth 0 applies
tests/actions to command line arguments only
-name PATTERN File name (w/o directory name) matches PATTERN
-path PATTERN Path matches PATTERN
-regex PATTERN Path matches regex PATTERN
-type X File type is X (X is one of: f,d,l,b,c,...)
-perm NNN Permissions match any of (+NNN), all of (-NNN),
or exactly (NNN)
-mtime DAYS Modified time is greater than (+N), less than (-N),
or exactly (N) days
-mmin MINS Modified time is greater than (+N), less than (-N),
or exactly (N) minutes
-newer FILE Modified time is more recent than FILE's
-inum N File has inode number N
-user NAME File is owned by user NAME (numeric user ID allowed)
-group NAME File belongs to group NAME (numeric group ID allowed)
-depth Process directory name after traversing it
-size N[bck] File size is N (c:bytes,k:kbytes,b:512 bytes(def.)).
+/-N: file size is bigger/smaller than N
-print Print (default and assumed)
-print0 Delimit output with null characters rather than
newlines USE_FEATURE_FIND_CONTEXT (
-context File has specified security context")
-exec CMD ARG ; Execute CMD with all instances of {} replaced by the
matching files
-prune Stop traversing current subtree
-delete Delete files, turns on -depth option
(EXPR) Group an expression
Example:
$ find / -name passwd
/etc/passwd
Wrap input lines in each FILE (standard input by default), writing to standard output
Options:
-b Count bytes rather than columns
-s Break at spaces
-w Use WIDTH columns instead of 80
Display the amount of free and used system memory
Example:
$ free
total used free shared buffers
Mem: 257628 248724 8904 59644 93124
Swap: 128516 8404 120112
Total: 386144 257128 129016
Free all memory used by the specified ramdisk
Example:
$ freeramdisk /dev/ram2
Check and repair filesystems
Options:
-A Walk /etc/fstab and check all filesystems
-N Don't execute, just show what would be done
-P When using -A, check filesystems in parallel
-R When using -A, skip the root filesystem
-T Don't show title on startup
-V Verbose
-C n Write status information to specified filedescriptor
-t type List of filesystem types to check
Perform a consistency check for MINIX filesystems
Options:
-l Lists all filenames
-r Perform interactive repairs
-a Perform automatic repairs
-v Verbose
-s Outputs super-block information
-m Activates MINIX-like "mode not cleared" warnings
-f Force file system check
Retrieve a remote file via FTP
Options:
-c, --continue Continue a previous transfer
-v, --verbose Verbose
-u, --username Username to be used
-p, --password Password to be used
-P, --port Port number to be used
Store a local file on a remote machine via FTP
Options:
-v, --verbose Verbose
-u, --username Username to be used
-p, --password Password to be used
-P, --port Port number to be used
Options:
-m Show all processes on the same mounted fs
-k Kill all processes that match
-s Don't print or kill anything
-4 When using port/proto only search IPv4 space
-6 When using port/proto only search IPv6 space
-SIGNAL When used with -k, this signal will be used to kill
Parse command options
-a, --alternative Allow long options starting with single -
-l, --longoptions=longopts Long options to be recognized
-n, --name=progname The name under which errors are reported
-o, --options=optstring Short options to be recognized
-q, --quiet Disable error reporting by getopt(3)
-Q, --quiet-output No normal output
-s, --shell=shell Set shell quoting conventions
-T, --test Test for getopt(1) version
-u, --unquoted Do not quote the output
Example:
$ cat getopt.test
#!/bin/sh
GETOPT=`getopt -o ab:c:: --long a-long,b-long:,c-long:: \
-n 'example.busybox' -- "$@"`
if [ $? != 0 ]; then exit 1; fi
eval set -- "$GETOPT"
while true; do
case $1 in
-a|--a-long) echo "Option a"; shift;;
-b|--b-long) echo "Option b, argument '$2'"; shift 2;;
-c|--c-long)
case "$2" in
"") echo "Option c, no argument"; shift 2;;
*) echo "Option c, argument '$2'"; shift 2;;
esac;;
--) shift; break;;
*) echo "Internal error!"; exit 1;;
esac
done
-a Show all SELinux booleans
Open a tty, prompt for a login name, then invoke /bin/login
Options:
-h Enable hardware (RTS/CTS) flow control
-i Do not display /etc/issue before running login
-L Local line, so do not do carrier detect
-m Get baud rate from modem's CONNECT status message
-w Wait for a CR or LF before sending /etc/issue
-n Do not prompt the user for a login name
-f issue_file Display issue_file instead of /etc/issue
-l login_app Invoke login_app instead of /bin/login
-t timeout Terminate after timeout if no username is read
-I initstring Sets the init string to send before anything else
-H login_host Log login_host into the utmp file as the hostname
Search for PATTERN in each FILE or standard input
Options:
-H Prefix output lines with filename where match was found
-h Suppress the prefixing filename on output
-r Recurse subdirectories
-i Ignore case distinctions
-l List names of files that match
-L List names of files that do not match
-n Print line number with output lines
-q Quiet. Returns 0 if PATTERN was found, 1 otherwise
-v Select non-matching lines
-s Suppress file open/read error messages
-c Only print count of matching lines
-o Show only the part of a line that matches PATTERN
-m MAX Match up to MAX times per file
-w Match whole words only
-F PATTERN is a set of newline-separated strings
-E PATTERN is an extended regular expression
-e PTRN Pattern to match
-f FILE Read pattern from file
-A Print NUM lines of trailing context
-B Print NUM lines of leading context
-C Print NUM lines of output context
Example:
$ grep root /etc/passwd
root:x:0:0:root:/root:/bin/bash
$ grep ^[rR]oo. /etc/passwd
root:x:0:0:root:/root:/bin/bash
Uncompress FILE (or standard input if FILE is '-')
Options:
-c Write output to standard output
-f Force read when source is a terminal
-t Test compressed file integrity
Example:
$ ls -la /tmp/BusyBox*
-rw-rw-r-- 1 andersen andersen 557009 Apr 11 10:55 /tmp/BusyBox-0.43.tar.gz
$ gunzip /tmp/BusyBox-0.43.tar.gz
$ ls -la /tmp/BusyBox*
-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/BusyBox-0.43.tar
Compress FILE(s) with maximum compression.
When FILE is '-' or unspecified, reads standard input. Implies -c.
Options:
-c Write output to standard output instead of FILE.gz
-d Decompress
-f Force write when destination is a terminal
Example:
$ ls -la /tmp/busybox*
-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/busybox.tar
$ gzip /tmp/busybox.tar
$ ls -la /tmp/busybox*
-rw-rw-r-- 1 andersen andersen 554058 Apr 14 17:49 /tmp/busybox.tar.gz
Halt the system
Options:
-d Delay interval for halting
-n No call to sync()
-f Force halt (don't go through init)
If no device name is specified try to read from stdin.
Options:
-a Get/set fs readahead
-A Set drive read-lookahead flag (0/1)
-b Get/set bus state (0 == off, 1 == on, 2 == tristate)
-B Set Advanced Power Management setting (1-255)
-c Get/set IDE 32-bit IO setting
-C Check IDE power mode status
-d Get/set using_dma flag
-D Enable/disable drive defect-mgmt
-f Flush buffer cache for device on exit
-g Display drive geometry
-h Display terse usage information
-i Display drive identification
-I Detailed/current information directly from drive
-k Get/set keep_settings_over_reset flag (0/1)
-K Set drive keep_features_over_reset flag (0/1)
-L Set drive doorlock (0/1) (removable harddisks only)
-m Get/set multiple sector count
-n Get/set ignore-write-errors flag (0/1)
-p Set PIO mode on IDE interface chipset (0,1,2,3,4,...)
-P Set drive prefetch count
-q Change next setting quietly
-Q Get/set DMA tagged-queuing depth (if supported)
-r Get/set readonly flag (DANGEROUS to set)
-R Register an IDE interface (DANGEROUS)
-S Set standby (spindown) timeout
-t Perform device read timings
-T Perform cache read timings
-u Get/set unmaskirq flag (0/1)
-U Un-register an IDE interface (DANGEROUS)
-v Defaults; same as -mcudkrag for IDE drives
-V Display program version and exit immediately
-w Perform device reset (DANGEROUS)
-W Set drive write-caching flag (0/1) (DANGEROUS)
-x Tristate device for hotswap (0/1) (DANGEROUS)
-X Set IDE xfer mode (DANGEROUS)
-y Put IDE drive in standby mode
-Y Put IDE drive to sleep
-Z Disable Seagate auto-powersaving mode
-z Re-read partition table
Print first 10 lines of each FILE to standard output. With more than one FILE, precede each with a header giving the file name. With no FILE, or when FILE is -, read standard input.
Options:
-n NUM Print first NUM lines instead of first 10
-c NUM Output the first NUM bytes
-q Never output headers giving file names
-v Always output headers giving file names
Example:
$ head -n 2 /etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
Display file(s) or standard input in a user specified format
Options:
-b One-byte octal display
-c One-byte character display
-C Canonical hex+ASCII, 16 bytes per line
-d Two-byte decimal display
-e FORMAT STRING
-f FORMAT FILE
-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 the hostname or DNS domain name. If a hostname is given (or FILE with the -F parameter), the host name will be set.
Options:
-s Short
-i Addresses for the hostname
-d DNS domain name
-f Fully qualified domain name
-F FILE Use the contents of FILE to specify the hostname
Example:
$ hostname
sage
Listen for incoming HTTP requests
Options:
-c FILE Configuration file (default httpd.conf)
-p [IP:]PORT Bind to ip:port (default *:80)
-i Inetd mode
-f Do not daemonize
-v[v] Verbose
-u USER[:GRP] Set uid/gid after binding to port
-r REALM Authentication Realm for Basic Authentication
-m PASS Crypt PASS with md5 algorithm
-h HOME Home directory (default .)
-e STRING HTML encode STRING
-d STRING URL decode STRING
Query and set a hardware clock (RTC)
Options:
-r Read hardware clock and print result
-s Set the system time from the hardware clock
-w Set the hardware clock to the current system time
-u The hardware clock is kept in coordinated universal time
-l The hardware clock is kept in local time
-f FILE Use the specified clock (e.g. /dev/rtc2)
Print information for USERNAME or the current user
Options:
-Z prints only the security context
-g Prints only the group ID
-u Prints only the user ID
-n Print a name instead of a number
-r Prints the real user ID instead of the effective ID
Example:
$ id
uid=1000(andersen) gid=1000(andersen)
Configure a network interface
Options:
[add ADDRESS[/PREFIXLEN]]
[del ADDRESS[/PREFIXLEN]]
[[-]broadcast [ADDRESS]] [[-]pointopoint [ADDRESS]]
[netmask ADDRESS] [dstaddr ADDRESS]
[outfill NN] [keepalive NN]
[hw ether ADDRESS] [metric NN] [mtu NN]
[[-]trailers] [[-]arp] [[-]allmulti]
[multicast] [[-]promisc] [txqueuelen NN] [[-]dynamic]
[mem_start NN] [io_addr NN] [irq NN]
[up|down] ...
Options:
-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 that this option doesn't disable mappings)
-v Print out what would happen before doing it
-m Don't run any mappings
-f Force de/configuration
Options:
-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 that this option doesn't disable mappings)
-v Print out what would happen before doing it
-m Don't run any mappings
-f Force de/configuration
Listen for network connections and launch programs
Options:
-f Run in foreground
-q N Set the size of the socket listen queue to N
(default: 128)
Init is the parent of all processes
This version of init is designed to be run only by the kernel.
BusyBox init doesn't support multiple runlevels. The runlevels field of the /etc/inittab file is completely ignored by BusyBox init. If you want runlevels, use sysvinit.
BusyBox init works just fine without an inittab. If no inittab is found, it has the following default behavior:
::sysinit:/etc/init.d/rcS
::askfirst:/bin/sh
::ctrlaltdel:/sbin/reboot
::shutdown:/sbin/swapoff -a
::shutdown:/bin/umount -a -r
::restart:/sbin/init
if it detects that /dev/console is _not_ a serial console, it will also run:
tty2::askfirst:/bin/sh
tty3::askfirst:/bin/sh
tty4::askfirst:/bin/sh
If you choose to use an /etc/inittab file, the inittab entry format is as follows:
<id>:<runlevels>:<action>:<process>
<id>:
WARNING: This field has a non-traditional meaning for BusyBox init!
The id field is used by BusyBox init to specify the controlling tty for
the specified process to run on. The contents of this field are
appended to "/dev/" and used as-is. There is no need for this field to
be unique, although if it isn't you may have strange results. If this
field is left blank, the controlling tty is set to the console. Also
note that if BusyBox detects that a serial console is in use, then only
entries whose controlling tty is either the serial console or /dev/null
will be run. BusyBox init does nothing with utmp. We don't need no
stinkin' utmp.
<runlevels>:
The runlevels field is completely ignored.
<action>:
Valid actions include: sysinit, respawn, askfirst, wait,
once, restart, ctrlaltdel, and shutdown.
The available actions can be classified into two groups: actions
that are run only once, and actions that are re-run when the specified
process exits.
Run only-once actions:
'sysinit' is the first item run on boot. init waits until all
sysinit actions are completed before continuing. Following the
completion of all sysinit actions, all 'wait' actions are run.
'wait' actions, like 'sysinit' actions, cause init to wait until
the specified task completes. 'once' actions are asynchronous,
therefore, init does not wait for them to complete. 'restart' is
the action taken to restart the init process. By default this should
simply run /sbin/init, but can be a script which runs pivot_root or it
can do all sorts of other interesting things. The 'ctrlaltdel' init
actions are run when the system detects that someone on the system
console has pressed the CTRL-ALT-DEL key combination. Typically one
wants to run 'reboot' at this point to cause the system to reboot.
Finally the 'shutdown' action specifies the actions to taken when
init is told to reboot. Unmounting filesystems and disabling swap
is a very good here.
Run repeatedly actions:
'respawn' actions are run after the 'once' actions. When a process
started with a 'respawn' action exits, init automatically restarts
it. Unlike sysvinit, BusyBox init does not stop processes from
respawning out of control. The 'askfirst' actions acts just like
respawn, except that before running the specified process it
displays the line "Please press Enter to activate this console."
and then waits for the user to press enter before starting the
specified process.
Unrecognized actions (like initdefault) will cause init to emit an
error message, and then go along with its business. All actions are
run in the order they appear in /etc/inittab.
<process>:
Specifies the process to be executed and its command line.
Example /etc/inittab file:
# This is run first except when booting in single-user mode
#
::sysinit:/etc/init.d/rcS
# /bin/sh invocations on selected ttys
#
# Start an "askfirst" shell on the console (whatever that may be)
::askfirst:-/bin/sh
# Start an "askfirst" shell on /dev/tty2-4
tty2::askfirst:-/bin/sh
tty3::askfirst:-/bin/sh
tty4::askfirst:-/bin/sh
# /sbin/getty invocations for selected ttys
#
tty4::respawn:/sbin/getty 38400 tty4
tty5::respawn:/sbin/getty 38400 tty5
# Example of how to put a getty on a serial line (for a terminal)
#
#::respawn:/sbin/getty -L ttyS0 9600 vt100
#::respawn:/sbin/getty -L ttyS1 9600 vt100
#
# Example how to put a getty on a modem line
#::respawn:/sbin/getty 57600 ttyS2
# Stuff to do when restarting the init process
::restart:/sbin/init
# Stuff to do before rebooting
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::shutdown:/sbin/swapoff -a
Load the specified kernel modules into the kernel
Options:
-f Force module to load into the wrong kernel version
-k Make module autoclean-able
-v Verbose
-q Quiet
-L Lock to prevent simultaneous loads of a module
-m Output load map to stdout
-o NAME Set internal module name to NAME
-x Do not export externs
Copy files and set attributes
Options:
-c Copy the file, default
-d Create directories
-g Set group ownership
-m Set permissions
-o Set ownership
-p Preserve date
-s Strip symbol tables
-Z Set security context of copy
ip [OPTIONS] OBJECT {COMMAND} where OBJECT := {address | route | link | tunnel | rule} OPTIONS := { -f[amily] { inet | inet6 | link } | -o[neline] }
| ipaddr { {add|del} IFADDR dev STRING | {show|flush} | |
| [dev STRING] [to PREFIX] } |
ipaddr {add|delete} IFADDR dev STRING ipaddr {show|flush} [dev STRING] [scope SCOPE-ID]
[to PREFIX] [label PATTERN]
IFADDR := PREFIX | ADDR peer PREFIX
[broadcast ADDR] [anycast ADDR]
[label STRING] [scope SCOPE-ID]
SCOPE-ID := [host | link | global | NUMBER]
Calculate IP network settings from a IP address
Options:
-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
The upper-case options MQS are used to remove a shared memory segment by a segment by a shmkey value. The lower-case options mqs are used to remove a segment by shmid value.
Options:
-[mM] Remove the memory segment after the last detach
-[qQ] Remove the message queue
-[sS] Remove the semaphore
-i Show a specific resource
Resource specification:
-m Shared memory segments
-q Message queues
-s Semaphore arrays
-a All (default)
Output format:
-t Time
-c Creator
-p Pid
-l Limits
-u Summary
iplink set DEVICE { up | down | arp | multicast { on | off } |
dynamic { on | off } |
mtu MTU }
iplink show [DEVICE]
| iproute { list | flush | { add | del | change | append | | |
| replace | monitor } ROUTE } |
iproute { list | flush } SELECTOR iproute get ADDRESS [from ADDRESS iif STRING]
[oif STRING] [tos TOS]
iproute { add | del | change | append | replace | monitor } ROUTE
SELECTOR := [root PREFIX] [match PREFIX] [proto RTPROTO]
ROUTE := [TYPE] PREFIX [tos TOS] [proto RTPROTO]
iprule [list | add | del] SELECTOR ACTION
SELECTOR := [from PREFIX] [to PREFIX] [tos TOS] [fwmark FWMARK]
[dev STRING] [pref NUMBER]
ACTION := [table TABLE_ID] [nat ADDRESS]
[prohibit | reject | unreachable]
[realms [SRCREALM/]DSTREALM]
TABLE_ID := [local | main | default | NUMBER]
| iptunnel { add | change | del | show } [NAME] | |
| [mode { ipip | gre | sit }] | |
| [remote ADDR] [local ADDR] [ttl TTL] |
iptunnel { add | change | del | show } [NAME]
[mode { ipip | gre | sit }] [remote ADDR] [local ADDR]
[[i|o]seq] [[i|o]key KEY] [[i|o]csum]
[ttl TTL] [tos TOS] [[no]pmtudisc] [dev PHYS_DEV]
Send a signal (default is TERM) to the specified process(es)
Options:
-l List all signal names and numbers
Example:
$ ps | grep apache
252 root root S [apache]
263 www-data www-data S [apache]
264 www-data www-data S [apache]
265 www-data www-data S [apache]
266 www-data www-data S [apache]
267 www-data www-data S [apache]
$ kill 252
Send a signal (default is TERM) to the specified process(es)
Options:
-l List all signal names and numbers
-q Do not complain if no processes were killed
Example:
$ killall apache
Send a signal (default is TERM) to all processes outside current session
Options:
-l List all signal names and numbers
Kernel logger
Options:
-c n Sets the default log level of console messages to n
-n Run in foreground
The BusyBox LAme SHell (command interpreter)
This command does not yet have proper documentation.
Use lash just as you would use any other shell. It properly handles pipes, redirects, job control, can be used as the shell for scripts, and has a sufficient set of builtins to do what is needed. It does not (yet) support Bourne Shell syntax. If you need things like ``if-then-else'', ``while'', and such use ash or bash. If you just need a very simple and extremely small shell, this will do the job.
Show listing of the last users that logged into the system
Print out the length of the specified STRING
Example:
$ length Hello
5
View a file or list of files. The position within files can be changed, and files can be manipulated in various ways.
Options:
-E Quit once the end of a file is reached
-M,-m Display a status line containing the current line numbers
and the percentage through the file
-N Prefix line numbers to each line
-~ Suppress ~s displayed when input past the end of the file is
reached
Create a link named LINK_NAME or DIRECTORY to the specified TARGET. You may use '--' to indicate that all following arguments are non-options.
Options:
-s Make symlinks instead of hardlinks
-f Remove existing destination files
-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
Example:
$ ln -s BusyBox /tmp/ls
$ ls -l /tmp/ls
lrwxrwxrwx 1 root root 7 Apr 12 18:39 ls -> BusyBox*
Load a console font from standard input
Example:
$ loadfont < /etc/i18n/fontname
Load a binary keyboard translation table from standard input
Example:
$ loadkmap < /etc/i18n/lang-keymap
Write MESSAGE to the system log. If MESSAGE is omitted, log stdin.
Options:
-s Log to stderr as well as the system log
-t TAG Log using the specified tag (defaults to user name)
-p PRIO Enter the message with the specified priority.
This may be numerical or a 'facility.level' pair.
Example:
$ logger "hello"
Begin a new session on the system
Options:
-f Do not authenticate (user already authenticated)
-h Name of the remote host for this login
-p Preserve environment
Print the name of the current user
Example:
$ logname
root
Show the messages from syslogd (using circular buffer)
Options:
-f Output data as the log grows
| losetup [-o OFS] LOOPDEV FILE - associate loop devices | |
| losetup -d LOOPDEV - disassociate | |
| losetup [-f] - show |
Options:
-o OFS Start OFS bytes into FILE
-f Show first free loop device
No arguments will display all current associations. One argument (losetup /dev/loop1) will display the current association (if any), or disassociate it (with -d). The display shows the offset and filename of the file the loop device is currently bound to.
Two arguments (losetup /dev/loop1 file.img) create a new association, with an optional offset (-o 12345). Encryption is not yet supported. losetup -f will show the first loop free loop device
List directory contents
Options:
-1 List files in a single column
-A Do not list implied . and ..
-a Do not hide entries starting with .
-C List entries by columns
-c With -l: show ctime
--color[={always,never,auto}] Control coloring
-d List directory entries instead of contents
-e List both full date and full time
-F Append indicator (one of */=@|) to entries
-i List the i-node for each file
-l Use a long listing format
-n List numeric UIDs and GIDs instead of names
-p Append indicator (one of /=@|) to entries
-L List entries pointed to by symlinks
-R List subdirectories recursively
-r Sort the listing in reverse order
-S Sort the listing by file size
-s List the size of each file, in blocks
-T NUM Assume Tabstop every NUM columns
-t With -l: show modification time
-u With -l: show access time
-v Sort the listing by version
-w NUM Assume the terminal is NUM columns wide
-x List entries by lines instead of by columns
-X Sort the listing by extension
-h Print sizes in human readable format (e.g., 1K 243M 2G)
-k Print security context
-K Print security context in long format
-Z Print security context and permission
List file attributes on an ext2 fs
Options:
-R Recursively list subdirectories
-a Do not hide entries starting with .
-d List directory entries instead of contents
-l Print long flag names
-v List the file's version/generation number
List the currently loaded kernel modules
Uncompress to stdout
Create a range of special files as specified in a device table. Device table entries take the form of: <type> <mode> <uid> <gid> <major> <minor> <start> <inc> <count> Where name is the file name, type can be one of:
f A regular file
d Directory
c Character special device file
b Block special device file
p Fifo (named pipe)
uid is the user id for the target file, gid is the group id for the
target file. The rest of the entries (major, minor, etc) apply to
to device special files. A '-' may be used for blank entries.
Example:
For example:
<name> <type> <mode><uid><gid><major><minor><start><inc><count>
/dev d 755 0 0 - - - - -
/dev/console c 666 0 0 5 1 - - -
/dev/null c 666 0 0 1 3 0 0 -
/dev/zero c 666 0 0 1 5 0 0 -
/dev/hda b 640 0 0 3 0 0 0 -
/dev/hda b 640 0 0 3 1 1 1 15
Will Produce:
/dev
/dev/console
/dev/null
/dev/zero
/dev/hda
/dev/hda[0-15]
-n Do not display path
-N Do not use translations
-f Use alternate file_context file
-p Use prefix to speed translations
-V Verify file context on disk matches defaults
Print or check MD5 checksums
Options: With no FILE, or when FILE is -, read standard input.
-c Check MD5 sums against given list
The following two options are useful only when verifying checksums:
-s Don't output anything, status code shows success
-w Warn about improperly formatted MD5 checksum lines
Example:
$ md5sum < busybox
6fd11e98b98a58f64ff3398d7b324003
$ md5sum busybox
6fd11e98b98a58f64ff3398d7b324003 busybox
$ md5sum -c -
6fd11e98b98a58f64ff3398d7b324003 busybox
busybox: OK
^D
-s Scan /sys and populate /dev during system boot
Called with no options (via hotplug) it uses environment variables to determine which device to add/remove.
The mdev config file contains lines that look like:
hd[a-z][0-9]* 0:3 660
That's device name (with regex match), uid:gid, and permissions.
Optionally, that can be followed (on the same line) by a special character and a command line to run after creating/before deleting the corresponding device(s). The environment variable $MDEV indicates the active device node (which is useful if it's a regex match). For example:
hdc root:cdrom 660 *ln -s $MDEV cdrom
The special characters are @ (run after creating), $ (run before deleting),
and * (run both after creating and before deleting). The commands run in
the /dev directory, and use system() which calls /bin/sh.
Config file parsing stops on the first matching line. If no config entry is matched, devices are created with default 0:0 660. (Make the last line match .* to override this.)
Control write access to your terminal
y Allow write access to your terminal
n Disallow write access to your terminal
Create the DIRECTORY(ies) if they do not already exist
Options:
-m Set permission mode (as in chmod), not rwxrwxrwx - umask
-p No error if existing, make parent directories as needed
-Z Set security context
Example:
$ mkdir /tmp/foo
$ mkdir /tmp/foo
/tmp/foo: File exists
$ mkdir /tmp/foo/bar/baz
/tmp/foo/bar/baz: No such file or directory
$ mkdir -p /tmp/foo/bar/baz
-b size Block size in bytes
-c Check for bad blocks before creating
-E opts Set extended options
-f size Fragment size in bytes
-F Force (ignore sanity checks)
-g num Number of blocks in a block group
-i ratio The bytes/inode ratio
-j Create a journal (ext3)
-J opts Set journal options (size/device)
-l file Read bad blocks list from file
-L lbl Set the volume label
-m percent Percent of fs blocks to reserve for admin
-M dir Set last mounted directory
-n Do not actually create anything
-N num Number of inodes to create
-o os Set the 'creator os' field
-O features Dir_index/filetype/has_journal/journal_dev/sparse_super
-q Quiet
-r rev Set filesystem revision
-S Write superblock and group descriptors only
-T fs-type Set usage type (news/largefile/largefile4)
-v Verbose
Create a named pipe (identical to 'mknod name p')
Options:
-m Create the pipe using the specified mode (default a=rw)
-Z Set security context
Make a MINIX filesystem
Options:
-c Check device for bad blocks
-n [14|30] Maximum length of filenames
-i INODES Number of inodes for the filesystem
-l FILENAME Read bad blocks list from FILENAME
-v Make a Minix version 2 filesystem
Create a special file (block, character, or pipe)
Options:
-m Create the special file using the specified mode (default a=rw)
TYPEs include:
b: Make a block (buffered) device
c or u: Make a character (un-buffered) device
p: Make a named pipe. MAJOR and MINOR are ignored for named pipes
-Z Set security context
Example:
$ mknod /dev/fd0 b 2 0
$ mknod -m 644 /tmp/pipe p
Prepare a disk partition to be used as swap partition
Options:
-c Check for read-ability
-v0 Make version 0 swap [max 128 Megs]
-v1 Make version 1 swap [big!] (default for kernels > 2.1.117)
block-count Number of block to use (default is entire partition)
Create a temporary file with its name based on TEMPLATE. TEMPLATE is any name with six 'Xs' (i.e., /tmp/temp.XXXXXX).
Options:
-d Make a directory instead of a file
-q Fail silently if an error occurs
Example:
$ mktemp /tmp/temp.XXXXXX
/tmp/temp.mWiLjM
$ ls -la /tmp/temp.mWiLjM
-rw------- 1 andersen andersen 0 Apr 25 17:10 /tmp/temp.mWiLjM
Options:
-k Make module autoclean-able
-n Just show what would be done
-q Quiet
-r Remove module (stacks) or do autoclean
-s Report via syslog instead of stderr
-v Verbose
modprobe can (un)load a stack of modules, passing each module options (when
loading). modprobe uses a configuration file to determine what option(s) to
pass each module it loads.
The configuration file is searched (in order) amongst:
/etc/modprobe.conf (2.6 only)
/etc/modules.conf
/etc/conf.modules (deprecated)
They all have the same syntax (see below). If none is present, it is _not_ an error; each loaded module is then expected to load without options. Once a file is found, the others are tested for.
/etc/modules.conf entry format:
alias <alias_name> <mod_name>
Makes it possible to modprobe alias_name, when there is no such module.
It makes sense if your mod_name is long, or you want a more representative
name for that module (eg. 'scsi' in place of 'aha7xxx').
This makes it also possible to use a different set of options (below) for
the module and the alias.
A module can be aliased more than once.
options <mod_name|alias_name> <symbol=value ...>
When loading module mod_name (or the module aliased by alias_name), pass
the "symbol=value" pairs as option to that module.
Sample /etc/modules.conf file:
options tulip irq=3 alias tulip tulip2 options tulip2 irq=4 io=0x308
Other functionality offered by 'classic' modprobe is not available in this implementation.
If module options are present both in the config file, and on the command line, then the options from the command line will be passed to the module _after_ the options from the config file. That way, you can have defaults in the config file, and override them for a specific usage from the command line.
Example:
(with the above /etc/modules.conf):
$ modprobe tulip
will load the module 'tulip' with default option 'irq=3'
$ modprobe tulip irq=5
will load the module 'tulip' with option 'irq=5', thus overriding the default
$ modprobe tulip2
will load the module 'tulip' with default options 'irq=4 io=0x308',
which are the default for alias 'tulip2'
$ modprobe tulip2 irq=8
will load the module 'tulip' with default options 'irq=4 io=0x308 irq=8',
which are the default for alias 'tulip2' overridden by the option 'irq=8'
from the command line
$ modprobe tulip2 irq=2 io=0x210
will load the module 'tulip' with default options 'irq=4 io=0x308 irq=4 io=0x210',
which are the default for alias 'tulip2' overridden by the options 'irq=2 io=0x210'
from the command line
View FILE or standard input one screenful at a time
Example:
$ dmesg | more
Mount a filesystem. Filesystem autodetection requires /proc be mounted.
Options:
-a Mount all filesystems in fstab
-f "Fake" Add entry to mount table but don't mount it
-n Don't write a mount table entry
-o option One of many filesystem options, listed below
-r Mount the filesystem read-only
-t fs-type Filesystem type
-w Mount for reading and writing (default)
Options for use with the ``-o'' flag:
loop Ignored (loop devices are autodetected)
[a]sync Writes are asynchronous / synchronous
[no]atime Disable / enable updates to inode access times
[no]diratime Disable / enable atime updates to directories
[no]dev Allow use of special device files / disallow them
[no]exec Allow use of executable files / disallow them
[no]suid Allow set-user-id-root programs / disallow them
[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
bind Bind a directory to an additional location
move Relocate an existing mount point
remount Remount a mounted filesystem, changing its flags
ro/rw Mount for read-only / read-write
There are EVEN MORE flags that are specific to each filesystem You'll have to see the written documentation for those filesystems
Returns 0 for success, number of failed mounts for -a, or errno for one mount.
Example:
$ mount
/dev/hda3 on / type minix (rw)
proc on /proc type proc (rw)
devpts on /dev/pts type devpts (rw)
$ mount /dev/fd0 /mnt -t msdos -o ro
$ mount /tmp/diskimage /opt -t ext2 -o loop
$ mount cd_image.iso mydir
mountpoint checks if the directory is a mountpoint
Options:
-q Quiet
-d Print major/minor device number of the filesystem
-x Print major/minor device number of the blockdevice
Example:
$ mountpoint /proc
/proc is not a mountpoint
$ mountpoint /sys
/sys is a mountpoint
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
Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY
Options:
-f Don't prompt before overwriting
-i Interactive, prompt before overwrite
Example:
$ mv /tmp/foo /bin/bar
Rename network interface while it in the down state
Options:
-c FILE Use configuration file (default is /etc/mactab)
-s Use syslog (LOCAL0 facility)
IFNAME MACADDR new_interface_name interface_mac_address
Example:
$ nameif -s dmz0 00:A0:C9:8C:F6:3F
or
$ nameif -c /etc/my_mactab_file
-l Listen mode, for inbound connects
B<-n> Do not do DNS resolution
B<-s> addr Local address
B<-p> port Local port
B<-u> UDP mode
B<-v> Verbose (cumulative: B<-vv>)
B<-w> secs Timeout for connects and final net reads
B<-i> sec Delay interval for lines sent" /* ", ports scanned" */
B<-o> file Hex dump of traffic
B<-z> Zero-I/O mode (scanning)
B<-e> prog [args] Program to exec after connect (must be last)/* "
B<-r> Randomize local and remote ports" */
To use netcat as a terminal emulator on a serial port:
$ stty 115200 -F /dev/ttyS0 $ stty raw -echo -ctlecho && nc -f /dev/ttyS0
Example:
$ nc foobar.somedomain.com 25
220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600
help
214-Commands supported:
214- HELO EHLO MAIL RCPT DATA AUTH
214 NOOP QUIT RSET HELP
quit
221 foobar closing connection
Display networking information
Options:
-l Display listening server sockets
-a Display all sockets (default: connected)
-e Display other/more information
-n Don't resolve names
-t Tcp sockets
-u Udp sockets
-w Raw sockets
-x Unix sockets
-r Display routing table
-W Display with no column truncation
Run a program with modified scheduling priority
Options:
-n ADJUST Adjust the scheduling priority by ADJUST
Monitor system in real time
| Format specifiers: | |
| %Nc or %[cN] | Monitor CPU. N - bar size, default 10 |
(displays: S:system U:user N:niced D:iowait I:irq i:softirq)
%[niface] Monitor network interface 'iface'
%m Monitor allocated memory
%[mf] Monitor free memory
%[mt] Monitor total memory
%s Monitor allocated swap
%f Monitor number of used file descriptors
%Ni Monitor total/specific IRQ rate
%x Monitor context switch rate
%p Monitor forks
%[pn] Monitor # of processes
%b Monitor block io
%Nt Show time (with N decimal points)
%Nd Milliseconds between updates (default=1000)
%r Print <cr> instead of <lf> at EOL
Example:
nmeter '%250d%t %20c int %i bio %b mem %m forks%p'
Run a command immune to hangups, with output to a non-tty
Example:
$ nohup make &
Query the nameserver for the IP address of the given HOST optionally using a specified DNS server
Example:
$ nslookup localhost
Server: default
Address: default
Name: debian
Address: 127.0.0.1
Write an unambiguous representation, octal bytes by default, of FILE to standard output. With no FILE, or when FILE is -, read standard input.
Start a command on a new virtual terminal
Example:
openvt 2 /bin/ash
Change a user password. If no name is specified, changes the password for the current user.
Options:
-a Define which algorithm shall be used for the password
(choices: des, md5)
" /* ", sha1)" */ B<-d> Delete the password for the specified user account
-l Locks (disables) the specified user account
-u Unlocks (re-enables) the specified user account
-p NUM Strip NUM leading components from file names
-i DIFF Read DIFF instead of stdin
Example:
$ patch -p1 < example.diff
$ patch -p0 -i example.diff
Display process(es) selected by regex pattern
Options:
-l Show command name too
-f Match against entire command line
-n Signal the newest process only
-o Signal the oldest process only
-v Negate the matching
-x Match whole name (not substring)
List the PIDs of all processes with names that match the names on the command line
USAGE_PIDOF
-s Display only a single PID
-o PID Omit given pid
Use %PPID to omit the parent pid of pidof itself
Example:
$ pidof init
1
$ pidof /bin/sh
20351 5973 5950
$ pidof /bin/sh -o %PPID
20351 5950
Send ICMP ECHO_REQUEST packets to network hosts
Options:
-4, -6 Force IPv4 or IPv6 hostname resolution
-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
Example:
$ ping localhost
PING slag (127.0.0.1): 56 data bytes
64 bytes from 127.0.0.1: icmp_seq=0 ttl=255 time=20.1 ms
--- debian ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 20.1/20.1/20.1 ms
Send ICMP ECHO_REQUEST packets to network hosts
Options:
-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
Example:
$ ping6 ip6-localhost
PING ip6-localhost (::1): 56 data bytes
64 bytes from ::1: icmp6_seq=0 ttl=64 time=20.1 ms
--- ip6-localhost ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 20.1/20.1/20.1 ms
Move the current root file system to PUT_OLD and make NEW_ROOT the new root file system
Send a signal to process(es) selected by regex pattern
Options:
-l List all signals
-f Match against entire command line
-n Signal the newest process only
-o Signal the oldest process only
-v Negate the matching
-x Match whole name (not substring)
Halt and shut off power
Options:
-d Delay interval for halting
-n No call to sync()
-f Force power off (don't go through init)
Print all or part of environment. If no environment VARIABLE specified, print them all.
Format and print ARGUMENT(s) according to FORMAT,
where FORMAT controls the output exactly as in C printf
Example:
$ printf "Val=%d\n" 5
Val=5
Report process status
USAGE_PS
-Z Show SE Linux context
w Wide output
Example:
$ ps
PID Uid Gid State Command
1 root root S init
2 root root S [kflushd]
3 root root S [kupdate]
4 root root S [kpiod]
5 root root S [kswapd]
742 andersen andersen S [bash]
743 andersen andersen S -bash
745 root root S [getty]
2990 andersen andersen R ps
Scan a host, print all open ports
Options:
-p Scan from this port (default 1)
-P Scan up to this port (default 1024)
-t Timeout (default 5000 ms)
-T Minimum rtt (default 5 ms, increase for congested hosts)
Print the full filename of the current working directory
Example:
$ pwd
/root
Tell the kernel to automatically search and start RAID arrays
Example:
$ raidautorun /dev/md0
Get and possibly set the system date and time from a remote HOST
Options:
-s Set the system date and time (default)
-p Print the date and time
Preload FILE(s) in RAM cache so that subsequent reads for thosefiles do not block on disk I/O
Display the value of a symlink
Options:
-f Canonicalize by following all symlinks
Options:
-m mapfile (Default: /boot/System.map)
-p profile (Default: /proc/profile)
-M mult Set the profiling multiplier to mult
-i Print only info about the sampling step
-v Verbose
-a Print all symbols, even if count is 0
-b Print individual histogram-bin counts
-s Print individual counters within functions
-r Reset all the counters (root only)
-n Disable byte order auto-detection
Return the absolute pathnames of given argument
Reboot the system
Options:
-d Delay interval for rebooting
-n No call to sync()
-f Force reboot (don't go through init)
Change priority of running processes
Options:
-n Adjusts 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
Resize the screen
Reset security contexts of files in pathname
-i Ignore files that do not exist
-f filename File with list of files to process. Use - for stdin
-e directory Directory to exclude
-R,-r Recurse directories
-n Don't change any file labels
-o filename Save list of files with incorrect context
-v Verbose
-vv Show changed labels
-F Force reset of context to match file_context
for customizable files, or the user section,
if it has changed
Remove (unlink) the FILE(s). You may use '--' to indicate that all following arguments are non-options.
Options:
-i Always prompt before removing each destination
-f Remove existing destinations, never prompt
-r,-R Remove the contents of directories recursively
Example:
$ rm -rf /tmp/foo
Remove the DIRECTORY, if it is empty
Example:
# rmdir /tmp/foo
Unload the specified kernel modules from the kernel
Options:
-a Remove all unused modules (recursively)
Example:
$ rmmod tulip
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