Search for files and perform actions on them. First failed action stops processing of current file. Defaults:

        -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:

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

Wrap input lines in each

        -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

Free all memory used by the specified ramdisk

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

Download a file via

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

Upload a file to a

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

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

Example:

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

        -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

Search for

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

Print the group memberships of

Decompress FILEs (or stdin)

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

Compress FILEs (or stdin)

        -d      Decompress
        -c      Write to stdout
        -f      Force

Halt the system

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

Print first 10 lines of each

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

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

Display FILEs (or stdin) in a user specified format

        -b              One-byte octal display
        -c              One-byte character display
        -C              Canonical hex+ASCII, 16 bytes per line
        -d              Two-byte decimal display
        -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 hostname or

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

Listen for incoming

        -i              Inetd mode
        -f              Don't daemonize
        -v[v]           Verbose
        -p [IP:]PORT    Bind to IP:PORT (default *:80)
        -u USER[:GRP]   Set uid/gid after binding to port
        -r REALM        Authentication Realm for Basic Authentication
        -h HOME         Home directory (default .)
        -c FILE         Configuration file (default {/etc,HOME}/httpd.conf)
        -m STRING       MD5 crypt STRING
        -e STRING       HTML encode STRING
        -d STRING       URL decode STRING

Query and set hardware clock (

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

Print information about

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

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] ...

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

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

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

Load the specified kernel modules into the kernel

Change I/O priority and class

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

ip [

Calculate

        -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

Send a signal (default:

        -l      List all signal names and numbers

Send a signal (default:

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

Kernel logger

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

Show listing of the last users that logged into the system

View

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

Create a link

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

Load a console font from stdin

Load a binary keyboard translation table from stdin

Write

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

Begin a new session on the system

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

Print the name of the current user

Show messages in syslogd's circular buffer

        -f      Output data as log grows

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

List directory contents

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

List the currently loaded kernel modules

Decompress to stdout

Decompress

        -d      Decompress
        -c      Write to stdout
        -f      Force

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

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

Print or check

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

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

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

It uses /etc/mdev.conf with lines         [-][ENV=regex;]...DEVNAME

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

Copy bytes for stdin to

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

Create

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

Create named pipe

        -m MODE Mode (default a=rw)

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

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

Prepare

        -L LBL  Label

Create a temporary file with name based on

        -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

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

        -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

View

Mount a filesystem. Filesystem autodetection requires /proc.

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

There are filesystem-specific -o flags.

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

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

Rename network interface while it in the down state. The device with address

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

Open a pipe to

        -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

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

Query the nameserver for the

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

Start

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

Change

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

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

List PIDs of all processes with names that match NAMEs

Send

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

Send

        -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

Move the current root file system to

Halt and shut off power

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

Format and print

Show list of processes

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

Print the full filename of the current working directory

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

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

Display the value of a symlink

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

Return the absolute pathnames of given

Reboot the system

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

Change scheduling priority for a running process

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

Reset the screen

Reverse lines of

Remove (unlink) FILEs

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

Remove

        -p|--parents    Include parents
        --ignore-fail-on-non-empty

Unload kernel modules

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

Edit kernel routing tables

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

Manipulate

Commands:

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

Output a cpio archive of the rpm file

Run a bunch of scripts in

        -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

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

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

Print numbers from

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

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

Run

Unix shell interpreter

Print or check

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

Print or check

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

Print or check

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

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 lines of text

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

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

Process matching:

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

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

Display file (default) or filesystem status

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

Valid format sequences for files:

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

Valid format sequences for file systems:

 %a     Free blocks available to non-superuser
 %b     Total data blocks in file system
 %c     Total file nodes in file system
 %d     Free file nodes in file system
 %f     Free blocks in file system
 %i     File System ID in hex
 %l     Maximum length of filenames
 %n     File name
 %s     Block size (for faster transfer)
 %S     Fundamental block size (for block counts)
 %t     Type in hex
 %T     Type in human readable form

Display printable strings in a binary file

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

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

Run shell under

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

Single user login

        -t N    Timeout

Stop swapping on

        -a      Stop swapping on all swap devices

Start swapping on

        -a      Start swapping on all swap devices

Free initramfs and switch to another root fs:

chroot to

        -c DEV  Reopen stdio to DEV after switch

Write all buffered blocks to disk

Show/set kernel parameters

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

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

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

Concatenate FILEs and print them in reverse

Print last 10 lines of each

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

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

Create, extract, or list files from a tar file

Operation:

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

Set or get

        -p      Operate on an existing PID

Copy stdin to each

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

Connect to telnet server

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

Handle incoming telnet connections

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

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

Transfer a file from/to tftp server

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

Run

        -v      Verbose

Runs

Provide a view of process activity in real time. Read the status of all processes from /proc each

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

Options:

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

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

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

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

Trace the route to

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

Trace the route to

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

Return an exit code of

Print file name of stdin's terminal