The following is a complete list of all Linux commands and their descriptions in alphabetical order:

#
Used to make comments in a shell script or tells witch shell to use as an interpreter for the script.

.
Reads commands from a script and execute them in your current environment.

/etc/hosts
Configures names and aliases of IP -addresses. Fields should be separated with Tab or white space.

/etc/inittab
Controls process dispatching. Used by init.

/etc/lilo.conf
Is the configuration file used by the Linux Loader while booting.

/etc/modules.conf
Loads modules specific options at startup.

/etc/nologin
Is a text file that, if it exists in /etc/, will prevent non-root users from logging in. If a user attempts to login, it will be shown the contents of the file, and then be disconnected.

/etc/nsswitch.conf
Specifies how the lookup for different databases are performed and in what order. Lookups are done left to right.

/etc/printcap
Describes printers and allows dynamic addition and deletion of printers by the spooling system.

/etc/resolv.conf
Configures DNS name servers to use for hostname lookups.

/etc/sysconfig/network
Configures the system's network. Specifies hostname and gateway.

/etc/xinetd.conf
Contains the configuration for the extended internet services started by the xinetd command.

a2p
Transforms awk scripts to perl scripts, and shows the result on STDOUT.

ab
Benchmarks your Apache server by sending requests to it.

access
Checks whether if a file can be accessed. Exits successfully if the file can be accessed with the specified mode.

actctrl
Configures the IBM Active 2000 ISDN device driver and downloads firmware into the ISDN card.

addftinfo
Reads troff font file and adds font metric information that is used by the groff system.

addr
Shows information about network addresses. Will show you the hexadecimal format of the IP address .

addr2line
Shows file names and line numbers for a specified program addresses.

adsl-connect
Is a user-space PPPoE client. It manages an ADSL connection and reestablishes a dropped connection.

adsl-setup
Is a PPPoE client configuration script. It is used for the adsl-start, adsl-stop and adsl-connect scripts.

adsl-start
Starts the Roaring Penguin user-space PPPoE client.

adsl-status
Shows status of the PPPoE link that was established by the Roaring Penguin user-space PPPoE client.

adsl-stop
Stops the Roaring Penguin user-space PPPoE client.

afm2tfm
Used to convert an Adobe font metric file to TeX font metric format.

ali
Shows addresses for mail aliases.

alias
Creates an alias for a command. If options aren't specified it will show all aliases.

allneeded
Forces the calculation of all fonts that are needed to preview a set of dvi files.

alloc
Shows how much memory is used and free.

anacron
Runs commands periodically

answer
Is a utility that secretaries can use for easily creating emails while recieving a phone call.

apm
Shows power status and can configure the server in standby or suspend mode.

apmd
Is a monitor daemon and works together with the APM BIOS driver in the OS kernel .

apmsleep
Sets the computer in suspend or sleep mode.

appres
Shows how much resources are used by a specific application.

apropos
Shows all manual pages that contain the specified keywords, including the section number and a short description.

ar
Creates and updates library files. It combines files into a single archive file.

arch
Shows the hardware architecture of the current host.

arp
Shows and alters the ARP table which is used to map MAC addresses to their assigned IP addresses.

arping
Ppings the destination address using arp packets on the specified interface.

arpsnmp
Saves the Ethernet/IP address pairings. Logs the activity to syslog and sends a report of the changes by e-mail.

arpwatch
Saves the Ethernet/IP address pairs. Logs the activity to syslog and sends a report of the changes by e-mail

as
Is an assembler that will create object files using assembly language source files as input.

as86
Assembles code for the 8086 to 80386 processors.

ascii-xfr
Sends or receives files in ASCII mode.

ash, bsh
Is a shell similar to sh with similar features as system V shell.

askrunlevel
Allows selection of the operation mode at boot time.

aspell
Checks for misspelled words. It has filter for e-mail, sgml, and TeX.

aspell (2)
More options

at
Schedules commands to be executed at a later time.

atd
Runs jobs that are queued by at.

atq
Shows any queued at jobs for the current user or for a specified user.

atrm
Removes jobs from the at or batch queues.

atrun
Runs jobs that are queued by the at command to run later. It is used for backward compatibility.

authconfig
Configures /etc/sysconfig/network to support NIS.

autoexpect
Inspects your actions in a command and creates an expect script that recreates your interactions.

avmcapictrl
Configures active AVM ISA cards.

avmcapictrl(2)
Loads the firmware to an active AVM ISA card.

badblocks
Searches a device for bad blocks.

banner
Shows the specified strings in large letters on STDOUT.

basename
Removes the prefix and suffix from a string and shows the output to STDOUT.

bash, sh
Is a free version of Bourne-shell with many features from C- TC- and Korn shell.

bashbug
Creates and sends bug reports about the bash shell to the address specified.

batch
Executes commands at a future time when the system load level permits. The commands is read from STDIN.

bc
Reads a file or STDIN and uses a C-like arithmetic language. Acts as a pre-processor for the command dc.

bcc
It is the Bruce's C compiler. A simple C compile that use K&R C syntax.

bdftopcf
Compiles a font for the X server and the font server. It converts BDF-fonts into PCF-fonts.

bg
Places the specified job in the background.

bind
Shows or binds key sequence to readline function or macro.

bindkey
Binds keys to an edit command. All bindings will be shown if no options is specified.

bison
Generates a parser program for specified grammar file.

bltin
Runs the internal command in the shell.

break
Exits from a for, foreach, while, select or until loop.

builtin
Forces the use of a shell that builtin commands.

builtins
Shows all built-in commands in tcsh.

bunzip2
Decompresses bzip2 files.

burst
Allows a message to be split into several new messages.

bzcat
Decompresses a bzip2 file to STDOUT.

bzip2
Compresses, decompresses or tests bzip2 files.

bzip2recover
Recovers data from a damaged bzip2 compressed file.

c++
Is a complete compiler for C, C++, and assembler.

c++filt
Organizes the C++ symbols.

cal
Shows the calendar for a selected month in the year, or the entire year.

cancel
Terminates a printer job.

captoinfo
Searches file for termcap descriptions and shows the equivalent terminfo description with any comments.

cardctl
Administers and controls the state of PCMCIA sockets.

cardmgr
Manages and monitors PCMCIA card sockets and does automatic installation/uninstallation.

case
Matches each pattern successively against the word and run the commands when the first match is found.

cat
Shows files and can also combine several files into one file.

cc
Is the C and C++ Compiler for Linux. See gcc or g++ for complete information.

cd, chdir
Changes the working directory. If no directory is specified $HOME is used.

cdecl
Encodes or decodes C or C++ type declarations.

cdp, cdplay
Controls and plays audio CDs interactively or non interactively.

cdparanoia
Reads audio tracks from a CD-ROM drive that is CDDA compatible.

cdrecord
Records data or audio to a CD-ROM with the specified CD recorder.

cfdisk
Controls and alters partitions on hard disk drives by use of interactive menus.

chage
Alters or shows the user password expiry information for the specified user.

charset
Changes one of the two slots for character sets.

chat
Controls a conversation automatically between two computers over a modem connection.

chattr
Alters the file attributes on a Linux second extended file system.

checkalias
Shows information about mail aliases.

checkpc
Administers information about entries in the printcap database.

chfn
Changes your finger information.

chgrp
Sets or changes the group ID for the file or files specified.

chkconfig
Administers runlevel information for system services.

chkfontpath
Configures the directories in the X font server path.

chmod
Alters or assigns permissions to a file.

chown
Alters the ownership ID of files and also sets the group ID if it is specified.

chpasswd
Updates the passwords for a group of users with name and password pairs from STDIN.

chroot
Alters the root directory for a command.

chsh
Changes your login shell.

chvt
Changes foreground virtual screen.

ci
Stores revisions in the specified revision control system files.

cjpeg
Creates a JPEG/JFIF image from a specified image file or from STDIN.

cksum
Calculates the checksum (CRC) and number of octets for each input file.

clear
Clears the screen of all information if not disabled by your terminal environment.

clockdiff
Measures clock difference between computers with the resolution of 1 msec.

cmp
Compares two files of any type and shows the line number and byte where the files differ.

co
Checks out a revision from a RCS file and stores it in the corresponding working file.

codepage
Extracts code pages from a file.

col
Converts spaces to Tabs or Tabs to spaces in text files to create or modify columns.

colcrt
Removes underlines or shows them on new lines filtering the nroff file for a CRT preview.

colrm
Deletes selected columns from a file reading from STDIN to STDOUT.

column
Formats input into multiple columns.

combine
Combines images together with new image.

comm
Compares two files and shows you the unique and common lines from both files.

command
Executes the command and will disable lookup functions in the current shell. Can also give information on how the command will be interpreted by the shell.

comp
Creates a mail message with a preconfigured form.

compgen
Generates possible completion matches for the specified word according to the option.

complete
Declares how a command should be completed. Use the Tab key to perform the completion on the command line.

compress
Compresses the size of a file and replaces the old file with a new file with the extension .Z. The new file will inherit the same permissions and modification times from the original file

conflict
Reports conflicts between nmh and the mail transport system.

consolechars
Changes console screen font, screenfont map, and / or application-charset map.

consolehelper
Authenticates users via PAM and runs the program specified including any options the command may have.

consoletype
Shows the screen (console) type that is currently connected to STDIN.

continue
Doesn't run the remaining commands in the loop and continue to the next iteration. Can be used in the commands for, while, until, select and foreach.

convert
Converts image formats, colors, sizes, creates filter effects, rotations, sequences, and more.

cp
Copies files and directories to a new destination.

cpio
Copies files into and out of a cpio archive. It operates in three different modes.

cpp
Is a C language preprocessor that insert include files in the source code of the source file creating a single file.

cproto
Creates C function prototypes and converts function definitions.

createdb
Creates databases on a postgres server.

createlang
Adds new programming languages to the specified postgres database.

createuser
Creates users in a postgres database.

cron, crond
Starts the cron daemon used to execute commands at scheduled dates and times specified in the crontab file.

crontab
Views, creates, deletes, or edits the crontab file which contains a list of jobs including the time and date they will execute. If option isn't given read from STDIN.

csplit
Splits whole or parts of a file into new files.

ctags, etags
Inserts tags into programming source code files f that can act as markers making it easier to find section headings quickly and edit them using ex or vi.

ctrlaltdel
Sets the function of the Ctrl+Alt+Del buttons used when rebooting a computer.

cut
Selects fields or columns from a text file or a table and shows the result to STDOUT.

cvs
Is a version control and logging system for files or directory tree structures including any versionable files.

cvsbug
Sends a CVS problem report to a central support site that runs GNATS.

cytune
Configures the interruption threshold for the Cyclades driver.

date
Shows current date and time or sets the date and time on your computer.

dbmmanage
Manages DBM files with user names and passwords to authenticate HTTP users.

dc
Is a calculator that use reverse-polish notation. It use a stack to performs calculations.

dd
Copies and converts an input file to an output file.

ddate
Shows the date in the discordian date format.

deallocvt
Disconnects the specified virtual terminal or terminals.

debugfs
Debugs the ext2 file system specified.

depmod
Controls dependency descriptions for loadable kernel modules.

df
Shows used and free disk space for all file system or the one specified.

dga
Tests video modes for X-window by filling the screen with different colors each time a key is pressed.

dhcpcd
Manages requests for an IP address from a DHCP server.

dhcrelay
Forwards BOOTP and DHCP requests from one subnet to another subnet.

dialog
Shows boxes containing questions or messages from the shell.

diff
Compares two text files in every line.

diff3
Compares the difference between three files.

diffstat
Creates statistic histograms from diff output.

dig
Gathers information from the DNS servers in interactive or batch mode.

dip
Controls dial-up or dial-in PPP connections. It dials using a specified dial-up script.

diplogin
Specifies the user name to login to the dial-in server that exists in the file /etc/diphosts.

dir
Shows files in the current directory or a specified directory.

dircolors
Shows or sets LS_COLORS environment variable.

dirname
Shows everything up to the last level of the given path name.

dirs
Shows the directory stack with the most recent one to the left.

dislocate
Disconnects a session without logging off to enable you to reconnect to the same session from another location.

disown
Removes the specified job from the active job list.

display
Shows images on the screen in X-window. Multiple images can be shown.

djpeg
Decompresses the JPEG file specified and creates an image file on the STDOUT.

dmesg
Examines and controls the kernel ring buffer

dnsdomainname
Shows the domain that you are in.

dnskeygen
Creates and maintains public, private, and shared secret keys for DNS servers.

dnsquery
Shows information about nameservers through BIND resolver library calls.

doexec
Runs a specified command showing it with another name passing the arguments provided.

domainname
Sets or shows the domain your system is configured for.

dosfsck, fsck.msdos
Checks a DOS file system; can also be used to fix damaged DOS file systems.

dp
Converts dates fitting the ARPA Internet standard (822 format).

dropdb
Removes a postgres database specified from the system.

droplang
Connects to a postgres database and removes a selected programming language.

dropuser
Connects to a postgres database and removes the specified user.

du
Shows disk usage for a directory and its subdirectories.

dump, rdump
Is a backup program that examines files in an ext2 file system and determines if the files need to be backed up.

dumpe2fs
Shows the super block and blocks group information of a file system present on a device.

dumpkeys
Shows the contents of the keyboard translation tables on STDOUT.

e2fsck, fsck.ext2
Checks Linux second extended file systems.

e2label
Shows or changes the label of an ext2 filesystem.

echo
Copies the written string to the screen. Exist as internal in all shells.

echotc
Exercises the terminal capabilities arguments.

ecpg
Is a preprocessor for embedded SQL code within C and Postgres programs.

ed
Is a line based editor. It is often used to edit files automatically in a script.

edquota
Manages user quotas for a ufs file system.

egrep
Shows lines form the file that matches the given pattern using full regular expressions.

eiconctrl
Configures active Eicon ISDN cards.

eject
Ejects floppies and CDs from their drives. Works for VM managed devices and devices without eject buttons.

elksemu
Emulates 8086 ELKS programs on an i386.

elm
Is an interactive mailer program that takes the place of mail and mailx.

elmalias
Shows information on specified elm aliases.

emacs
Edits text files, read and send mail, perform outline edits, compiles and run subshells.

enable
Enables or disables internal commands.

env
Alters the current environment and invokes a utility or shows the current environment.

eqn, geqn
Preprocesses files for troff which contain mathematics equations.

eval
Reads the argument as input to the shell and runs the resulting commands.

ex, e
Is a line base text editor. It is able to work on several files at the same time.

exec
Runs a command in place of the current shell. Usually another shell.

exit
Exits a shell or shell script with an exit status

expand
Replaces Tabs with spaces in text files. If no input files are specified STDIN will be used.

expect
Is used to automatically control interactive programs. It acts by reading commands from a file.

expectk
Is used to automatically control interactive programs. Is the same as expect, With Tk support.

export
Exports a shell variable to environment.

exportfs
Controls the exported file system table for NFS.

expr
Evaluates an expression and show the result to STDOUT.

extcompose
Creates a file containing a reference to external files on the computer.

factor
Finds the prime factor of a number. Also shows if the number is a prime factor.

faillog
Manages the summary of failures in /var/log/faillog.

false
Provides a false value in scripts, does nothing but always exits with a non zero-value.

fastmail
Sends e-mails fast in a batch to a large group of receivers.

fc
Reruns, edits or lists commands that have recently been used. With no options, edits and runs the last command.

fdformat
Formats new diskettes.

fdisk
Handles partiton tables. If no arguments is specified, an interactive prompt will be used.

fetchmail
Retrieves mail from POP , IMAP, or ETRN servers and forwards it to your local mail agent.

fg
Resumes the execution of a stopped job in the foreground. Without an argument the current job is used.

fgconsole
Shows you the number of the active virtual terminal.

fgrep
Shows lines form the file that matches the given pattern.

file
Performs tests on each file that you have specified to determine what file type it is.

filetest
Tests a file for different things.

find
Finds files in the specified directories and subdirectories using the Boolean expression from the input line.

findsmb
Shows information about computers on the network running MS Windows operating systems.

finger, safe_finger
Shows information about logged in users.

flex, flex++, lex
Creates a scanner program that recognizes lexical patterns in a text.

fmt
Is a text formatter. It will take the text from the file and produce output lines that are joined in the correct way.

fold
Breaks lines in text files to the specified width.

folder, folders
Shows the current folder and information about the messages in it.

for
Is used to go trough each word in the list, assign the value to variable and run the commands.

foreach
Is used to go trough each word in the list, assign the value to variable and run the commands.

fortune
Shows an interesting or funny phrase from various people randomly each time you execute it.

free
Shows the amount of free and used memory in the system.

fsck
Checks file systems for inconsistencies and repair them.

fsck.minix
Checks the minix file system for consistency.

fsinfo
Shows information including the capabilities about X font servers on the network.

fslsfonts
Shows the fonts on the font server that match the pattern specified. Wildcards (*) can be used.

fstobdf
Creates BDF fonts from an X font server. Debugs font and re-create BDF files.

ftl_check
Shows bookkeeping information for a Flash Translation Layer partition .

ftl_format
Formats a Flash Translation Layer partition on a flash memory device.

ftp
Transfers files from a remote network. It uses the File Transfer Protocol .

ftpcount
Shows current number of users using the FTP server.

ftprestart
Automatically restarts shutdown FTP servers.

ftpshut
Is an automatic shutdown procedure that notifies FTP users when the server is shutting down.

ftpwho
Shows information about the current processes for each FTP user.

function
Defines function in a shell.

funzip
Extracts the first file from a zip archive within a pipe to the standard, or specified, input.

fuser
Shows all processes that are using the specified files or file systems.

g++
Is the C++ compiler version of gcc. It assumes that the preprocessed files .i are in C++.

g77, f77
Is the GNU Fortran compiler. This can also be started using f77.

gawk, awk
Is a processing language from GNU built from awk and supports all of the options found in awk.

gcc
Is the GNU C/C++ compiler. It assumes that the preprocessed .i files are C based.

gdb
Is the GNU debugger program. This can start a specified program and modify its behavior.

gendiff
Generates a diff file that contains the differences between two directories.

genksyms
Creates a file with version information by first running gcc -E on it.

getconf
Retrieves current configuration values and show them to STDOUT.

getent
Retrieves entries using keywords that must already exist from a system configuration file.

getfilename
Uses a file in the specified format, then creates a copy of it using the specified file name.

getkeycodes
Shows kernel scan-code to key-code mapping table. Can be used to define functions of special keys.

getopt
Cleans up and checks options given to a shell script. It split option given together and place each option in its own variable. Any additional arguments is placed after --

getopts
Will retrieve or set environment options and process them from the command line. The values specified by name and the index of the next arguments are placed into the shell variable OPTIND.

gettext
Gets the domain name variable from a message object made by msgfmt.

gif2tiff
Creates a TIFF image file from a GIF image file.

glob
Performs file name expansion on the words. The result is separated by a NULL-character.

goto
Jumps to label in a shell script.

gpasswd
Administers the /etc/group and /etc/gshadow files.

gpg
Is the main security program for the GNUPG system and can check, sign, encrypt and decrypt.

gphoto
Administers picture handling with digital cameras. Can also be used with Web cameras and in scripts.

gpm
Enables the mouse in screen mode and sets various attributes such as baud rate and mouse type.

gpm-root
Allows Control-Mouse events to be able to draw menus during screen mode.

gprof
Shows an execution (call-graph) profile of a program. It can also create files containing portions of this information.

grep
Shows lines form the file that matches the given pattern.

grodvi
Is a groff driver that creates TeX dvi files that can then be printed out.

groff
Is the front end to the document formatting system used by groff.

grog
Guesses which groff option is required for printing a specific file and sends this answer to STDOUT..

grolj4
Is a groff driver that is used for creating output that can be printed onto an HP LaserJet 4 type printer.

grops
Translates GNU troff output into PostScript.

grotty
Translates GNU troff output into a simple printer format.

groupadd
Creates a new group definition on the system.

groupdel
Deletes a specified group definition in the system.

groupmod
Alter's a specific group definition on the system.

groups
Shows the groups that a user is a member of.

grpck
Checks the integrity of the /etc/group and /etc/gshadow files.

grpconv
Updates the /etc/gshadow if the /etc/group file has been changed manually.

grpunconv
Creates the /etc/group file from the /etc/gshadow file, then removes the /etc/gshadow file.

gs
Starts Ghostscript and reads Adobe Systems PostScript and PDF files.

gtbl
Compiles descriptions of any tables that are embedded inside troff files.

gunzip
Extracts files created by gzip, zip, compress or pack.

gv
Allows you to view PostScript and PDF documents.

gzexe
Compresses executable files into a self extracting archive.

gzip
Compresses files with Lempel Ziv-coding.

h2ph
Converts the specified C header files into Perl header file format.

h2xs
Creates Perl extensions from C header files.

halt
Writes any remaining data in memory to the disks and then stops the computer.

hash
Shows or changes information in the internal hash table that stores information about executed commands.

hashstat
Show information about how effective the internal hash table is.

hdparm
Sets or retrieves hard drive parameters.

head
Show lines from the beginning of each file on the screen.

help
Shows help information about internal commands.

hexdump
Dumps a file in hexadecimal format on the screen.

hisaxctrl
Setups the HiSax-ISDN device driver, if you are using the HiSax driver.

history
Shows a list of previously used commands, and can optionally execute them again.

host
Looks up hostnames or IP-addresses using name servers.

hostid
Shows na identifier for the current host in hexadecimal format.

hostname
Sets or shows the hostname for the computer.

hpftodit
Uses an HP tagged font metric file and creates a font file for use with groff -Tlj4.

htdigest
Manages HTTP user authentication files.

htpasswd
Manages HTTP user authentication.

httpd
Is the Apache internet Web server.

hup
Allows a command to catch a hangup signal. This is the opposite of nohup.

hwclock, clock
Shows and configures the hardware clock.

ibench
Shows how many connections the daemon can manage during a specified time. Will also identify users.

iceauth
Modifies or shows authorization information to connect with ICE.

id
Shows the userID and groupID of the user that you specify.

ident
Searches for RCS keyword strings in files.

if
Makes a decision inside a shell script. If the first expr is true run the first commands. If not check the next expr and so on. If no expr was true run commands after then.

ifcfg
Configures the Ethernet interfaces.

ifconfig
Configures network interface parameters or show the status for network interface.

ifdown
Deactivates a network interface.

ifport
Set or views the transceiver type for the network interface.

ifup
Activates a network interface.

ifuser
Shows whether any of the specified hosts are routed through the specified interface.

igawk
Adds the ability to have include files in gawk. It accepts all gawk options. Gawk also includes additional options from Bell Labs and GNU specific options.

imon
Monitors your ISDN activities.

imontty
Shows the status of all ISDN lines.

import
Captures some or all of an X server screen and saves it to a file.

in.fingerd, fingerd
Is the daemon the manages the finger protocol.

in.ftpd, ftpd
Is the Internet FTP daemon that manage FTP services. It is only started by the inetd daemon when requested.

in.identd, identd
Returns user information about the owner of a connection to a remote computer.

in.rexecd, rexecd
Is a daemon that services remote execution requests and uses use rname and password authentication. inetd will automatically start the daemon when needed.

in.rlogind, rlogind
Is the server for the rlogin command. The server looks at client's source port. If port is not in the range 0-1023, the server will abort the connection.

in.rshd, rshd
Is the server for rsh (remote shell) and allows clients to execute commands from remote clients. The server accepts connections from the client on any port lower the 1024.

in.telnetd, telnetd
Used to process incoming requests on the telnet port. Started by the Internet Server (inetd).

in.tftpd, tftpd
Is a server that gives you TFTP functionality, it uses the UDP protocol instead of TCP.

indent
Inserts or erases whitespace in C code to make it easier to read. Converts from one C style to another.

indxbib
Creates an index for a database file in inverted form. It can be read by the commands lookbib and refer. Is an executable in Linux, BSD and a script in AIX, Solaris.

info
Reads hypertext info nodes. Info nodes fill the same function on as man pages.

infocmp
Shows terminal information or compare descriptions between two or more terminals.

infotocap
Reads the specified file and converts found terminfo descriptions to termcap descriptions. The converted descriptions is shown on STDOUT.

init, telinit
Changes run levels for the system. Shuts down or restart the computer in different modes.

initdb
Creates a new Postgres database system.

initlocation
Creates another Postgres secondary database storage area.

initlog
Sends log messages to the system logging facility.

insmod
Installs loadable kernel modules (device drivers) in the running kernel.

install
Manages the installation of files to a specific location or creates directories in a file system.

install-info
Installs or erases menu entries in info directory files.

install-mh
Creates the initial setup for a first-time nmh user.

iostat
Shows input and output statistics for disks, terminals and tapes.

ipcalc
Calculates IP address information.

ipcclean
Cleans up shared memory and semaphores from aborted backends.

ipchains
Manages IP firewall rules in the Linux 2.2 kernel.

ipchains-restore
Restores IP firewall chains from STDIN.

ipchains-save
Shows the firewall chains on the screen.

ipcrm
Releases shared memory by removing identifiers from message queues, semaphores, and shared memory segments that programs or services have left behind.

ipcs
Shows information about inter-process communications currently active in the system, such as shared memory segments, semaphores and message queues.

ipppd
Is a modified pppd that provides synchronous PPP support for ISDN connections.

ipppstats
Shows PPP-related statistics.

iprofd
Creates the modem register of the ISDN-ttys AT-emulator permanent.

iptables
Manages IP firewall rules in the Linux 2.4 kernel.

iptunnel
Configures various types of IP tunnels.

ipx_cmd
Is a bridge between local IPX network and Novell's SCMD driver.

ipx_configure
Queries or configures IPX behavior with respect to automatic IPX interface detection.

ipx_interface
Manages IPX interfaces.

ipx_internal_net
Adds or removes the IPX internal network.

ipx_route
Adds or removes an IPX route.

isapnp
Reads the configuration file to configure ISA PnP cards.

isdnconf
Manipulates or reads ISDN phone number config files.

isdnctrl
Configures ISDN device information.

isdnlog
Shows decoded information from the ISDN card.

isdnrate
Shows telephone rates and various info from rate files.

isdnrep
Shows ISDN activity.

isoinfo
Does directory-like listings of iso9660 images.

isovfy
Checks an iso9660 image for errors.

ispell
Is a compatibility script for the aspell spell checker.

jobid
Shows the process id for the job or for the current job if not given.

jobs
jobs is used to report all jobs that are stopped or executing in the background.

join
Compares two files and joins them together where the fields are identical and show the result to STDOUT.

jpegtran
Converts JPEG from one compression to another.

kbdconfig
Configures the keyboard.

kbdrate
Changes keyboard configurations.

kbd_mode
Changes the keyboard translation mode. Useful when a program don't restore the translation mode.

kernelversion
Shows the major version of the kernel.

kibitz
Allows multiple interactions to one shell.

kill
Stops a process or sends a signal to a processes.

killall
Kills all processes running the specified commands.

killall5
Kills all processes but the ones in it's own session. Same as the System V killall command.

klogd
Is a daemon that is used to log kernel messages.

ksymoops
Decodes Linux kernel Oops.

ksyms
Shows kernel symbols that have been exported.

kudzu
Checks the hardware. If there are some changes in the system, it gives the opportunity to configure the hardware.

LANG=language
Change the regional setting and language translation.

last
Shows login information about users, hosts, and terminals.

lastb
Shows all bad login attempts.

lastlog
Shows the contents of the last login log. The information includes login name, port, and last login time.

lbxproxy
Is an X proxy that uses the low bandwidth extension to X (LBX). Some optimizations is made to the connections that increases speed over slow connections.

lc
Runs the last function specified by function or the last command entered

ld
Is a linker for object files used to link executables or shared libraries. Ld operates in two modes, static or dynamic.

ld86
Links object files produced by the as86 assembler into I&D executables.

ldconfig
It is used to configure run time bindings for the dynamic linker.

ldd
Shows a list of executable files and their dynamic dependencies or shared objects

less
Is a text pager for UNIX system, used to show ASCII files.

lesskey
Manages key bindings for less.

let
Performs arithmetic calculations using the arguments specified, can be used in advanced shell scripts.

let
Will evaluate the arguments and if the result is zero the exit status is 1 otherwise 0.

lex
Creates C programs to be used in lexical processing of character input. That can be used as an interface to yacc.

lilo
Allows you to have several operating systems installed and boot into any of them at startup.

limit
Set limitations on the system resources available to the current shell.

links
Is a simple command-line URL browser.

linuxconf
Is an interactive menu configuration program.

listalias
Shows user and system mail aliases in the system. This is one part of the elm mailer.

listres
Creates a list of widget's names and classes.

lkbib
Finds references in the bibliographic database that contain the specified keyword.

ln
Creates a link between the specified source and destination files.

lndir
Makes a shadow directory tree from fromdir with symbolic links.

loadkeys
Reads and modifies the keyboard translation tables.

local
Creates a local variable within a function and set variable's attribute.

locale
Shows locale-specific information.

localedef
Compiles or creates locale specifications.

lockfile
Creates semaphore files used to limit the access so that only one program is allowed to access the file or files.

logger
Adds messages to the system log from the command line.

login
Lets you sign on to the system.

logname
Shows your login name.

logout
Exits a login shell form in Bash, C, TC and Z-Shell (bash, csh, tcsh, zsh).

logresolve
Resolves IP addresses in Apache's access log files. This is to reduce the impact for the name server.

logrotate
Administrates log files by rotating, compressing, removing, and mailing the log files.

look
Will find words in the system dictionary and show all lines that begins with the specified string.

lookbib, glookbib
Finds references in a bibliographic database and recover records containing the keywords entered at the prompt.

loopctrl
Configures the isdnloop ISDN driver.

losetup
Administers and controls loop devices.

lp
Sends print request to a printer or printer queue.

lpbanner
Show a banner on a fixed-size font printer.

lpc
Used by the system administrator to control the operation of the line printer system.

lpd
Starts the printer server.

lpf
Is used as a general printer filter. It is often used in the printcap file as a filter.

lpq
Shows the content of a print queue.

lpr
Sends print requests to a printer. Will use STDIN if no file is specified.

lpraccnt
Is a printer accounting program template. It opens a specified TCP port for to send information

lprm
Removes print requests from the print queue and report the file's name of removed request.

lpstat
Shows status information on a printer or printer queue.

lpunlock
Unlocks a printer that is waiting for lock.

ls
Lists the contents of a specified directory and supports wildcards.

ls-F
Lists files like ls -F. It's much faster than ls.

lsattr
Shows the file attributes on a Linux second extended file system.

lsmod
Shows information about the loaded modules.

lsof
Shows a listing of open files.

lspci
Shows information about all PCI buses in the system and all devices connected to them.

ltrace
Traces library calls of a given program.

lynx
Is a fully featured, text only WWW browser. Shows HTML documents with links to files on the local system and for remote hosts running HTTP, FTP, NNTP , WAIS, and Gopher.

m4
Is a front end macro processor that is used for programming languages like C and assembler.

mail, Mail, mailx
Reads and sends mail.

mailq
Shows the mail queue. Shows first line for each mail massage, host for the massage, size the date and time.

mailstats
Shows the statistics collected by the program sendmail.

mailto
Sends multimedia mail in MIME format. It can only be used to send mail.

make, gmake
Updates a target file and all of its dependencies or repairs missing or invalid target dependency trees.

makedbm
Creates a DBM file or converts a DBM file to a text file.

makedepend
Reads each specified source file in the given sequence and then parses it.

MAKEDEV
Creates device entries in the /dev directory.

makeg
Makes an executable file that can be used for debug operations.

makeinfo
Converts Texinfo files to plain text, HTML or info files for online reading.

makemap
Uses the keyed map lookups in sendmail and creates the database map by reading from STDIN.

makepsres
Creates an PostScript language database file that contains the resources in the specified path names.

makestrs
Creates string table C source files and headers and outputs them on STDOUT.

makewhatis
Updates the whatis database.

make_smbcodepage
Creates a codepage for use with Samba.

man
Shows the manual page of the specified command.

man2html
Converts manual pages to HTML format.

manpath
Shows search paths for man pages.

mattrib
Changes file attributes for MS-DOS files

mbadblocks
Tests a floppy disk for bad blocks and marks them in the file allocation table.

mc
Is a file manager used to browse directories and files.

mcat
Copies a disk image to or from a floppy disk.

mcd
Changes directory in a MS-DOS directory structure.

mcedit
Edits file. It starts Midnight Commander (mc) in edit mode.

mcookie
Creates a magic cookie that works with the command xauth.

mcopy
Copies MS-DOS files to or from a UNIX system.

md5sum
Verifies MD5 checksums.

mdel
Deletes a file in an MSDOS file system..

mdeltree
Deletes a directory from an MSDOS file system.

mdir
Shows files in an MSDOS directory.

mdu
Shows disk usage for a specific file or files on an MS-DOS file system.

merge
Merges three files together. It merges the changes between input file 2 and 3 into input file number 1.

mesg
Allows or disallows messages to be sent to your terminal.

messages
Shows how many messages you have in your mailbox or folder.

metamail
Manages how to show mails that are non text-based.

metasend
Sends non text mails.

mformat
Formats MS-DOS floppy disks.

mhl
Shows and filters text messages in New Messages Handling System (NMH).

mhmail
Reads or sends mail.

mhpath
Shows pathnames to folders and mailboxes.

mikmod
Plays modules on a UNIX system.

mimencode
Converts or deconverts any standard mail-encoding formats defined by MIME.

mingetty
Is a smaller getty that works with virtual consoles.

minicom
Is a text-based window serial communication program.

mkbootdisk
Creates a boot floppy for the running system.

mkdep
Creates makefile dependency lines for a specified source file.

mkdir
Ccreates directories.

mkdirhier
Creates the specified directories including any unspecified parent directories as well.

mkdosfs, mkfs.msdos
Creates an MS-DOS file system in Linux.

mke2fs, mkfs.ext2
Creates a second extended file system.

mkfifo
Creates the FIFO special files specified by the paths and filenames on the command line.

mkfontdir
Creates an index file from any X font files found in a directory. It typically looks for .pcf, .snf and .bdf fonts and then creates the file fonts.dir in the same specified directory.

mkfs
Creates a Linux file system on the specified device.

mkfs.minix
Creates a minix file system.

mkinitrd
Create a ramdisk to preload modules to gain access to the root file system.

mkisofs
Creates an ISO9660, Joliet, or HFS file system that is used on CDs and handles Rock Ridge attributes.

mklost+found
Creates a lost+found directory.

mkmanifest
Creates a shell script that restores UNIX file names that has been shortened by MS-DOS file systems.

mknetid
Creates the NIS netid map called netid.byname using the contents of the hosts, passwd, group and netid files.

mknod
Creates a directory entry for a specified special file.

mkpasswd
Generates a new password and assigns it to a user if you specify one.

mkraid
Manages RAID arrays.

mkswap
Creates a swap area in Linux.

mktemp
Creates a temporary file name using another file name as a template.

mktexlsr
Manages ls-R databases.

mkxauth
Manages .Xauthority files.

mlabel
Creates a volume label on MS-DOS file systems.

mmd
Create directories on MS-DOS file systems.

mmount
Mounts a MS-DOS file system in Linux.

mmove
Moves files on MS-DOS file systems.

modinfo
Shows information about the specified kernel module.

modprobe
Probes for modules in Linux.

mogrify
Modifies images by scaling, rotating, twisting and cropping. It also converts image files.

more
Shows a textfile one page at a time. Continues reading files specified on the command line.

mount
Mounts a file system or shows a file system that is already mounted. The file system can be local or remote.

mountd, rpc.mountd
Answers file system mount requests and NFS access information checks.

mouseconfig
Manages mouse configuration.

mpage
Prints several pages on one sheet of paper. The input files can be either plain text or PostScript.

mpartition
Partitions an MS-DOS hard disk, to create an MS-DOS file system.

mpg123
Reads files or URLs and plays them on the audio device or outputs them to STDOUT.

mrd
Deletes an MS-DOS directory.

mren
Renames or moves MS-DOS files.

msgchk
Checks maildrops for new incoming mail messages.

msgfmt
Creates message object files from portable object files. It doesn't change the portable object files.

msh
Reads a usual mail message file or a message file compressed with packf.

mshowfat
Shows file allocation table entries for an MS-DOS file.

mt
Sends commands to a tape device.

mtools
Shows all the programs in the mtools package which are used for accessing DOS FAT volumes.

mtype
Shows the content of an MS-DOS file.

mutt
Manages mail boxes. Sends and reads e-mails.

mv
Moves or renames files and directories.

mzip
Sends commands to an Iomega ZIP drive.

named, in.named
Is the domain name server that answers DNS request and resolves host names and finds their assigned IP address.

named-xfer
Handles inbound zone transfer. Is used by named and should not be used directly.

namei
Shows which kind of file each part of a pathname is. Follows symbolic links until they stop in a proper file.

ncftp
Is a browser program for the Internet FTP service.

ncftpbatch
Processes FTP requests added by the ncftp program.

ncftpget
Transfers files from the command line or shell scripts instead of using interactive FTP programs.

ncftpls
Creates remote directories listings without using interactive FTP programs.

ncftpput
Transfers files from the command line or shell scripts instead of using interactive FTP programs.

ncopy
Copies files over the NetWare network.

ncpmount
Mounts volumes on a NetWare file server.

ncpumount
Unmounts a NetWare file system that was previously mounted with the ncpmount.

ndc
Administers and manages the operations of a name server.

neqn
Is a preprocessor for the command nroff and is used to help out in equations.

netconf
Is an interactive user interface that allows configuration of a TCP/IP network.

netconfig
Configures the network on the command line or in interactive mode.

netreport
Requests network management scripts send a SIGIO signal when network interface changes occur.

netscape
Is a graphic based web browser.

netstat
Shows statistics and other network information, based on options selected.

newalias
Installs new elm aliases for system and/or user.

newaliases
Rebuilds the mail aliases file.

newer
Compares modification times of two files and exits successfully if file1 is at least as old as file2.

newgrp
Changes a user's real and effective group ID to the specified group.

newusers
Updates and creates new users in batch. User information is taken from the specified file.

nfsd, rpc.nfsd
Manages NFS file system requests for clients.

nfsstat
Shows NFS and RPC statistics.

nhfsstone
Benchmarks Network File System (NFS).

nice
Starts commands to be run in a different priority.

nisdomainname
Shows or sets system's NIS domain name.

nl
Reads lines from STDIN or a file, adds line numbers, and shows the result to STDOUT.

nm
Shows a table of the symbol names used for the specified ELF object file.

nmbd
Is a server that replies to NetBIOS over IP name service requests from a Windows client.

nmblookup
Requests NetBIOS names and maps them to IP addresses.

nohup
Is a way to run a command which will be immune to any hang up signals.

notify
Will notify a user asynchronous when the status of a job is changed. If job is not given, the current job is used.

nprint
Prints files to print queues located on a NetWare file server.

nroff
Processes a text file and formats the output for use with a letter quality printer or line printer.

nsend
Sends messages to NetWare users or user groups.

nslookup
Contacts and sends queries to DNS servers interactively or non-interactively.

nsupdate
Updates DNS name servers interactively or non-interactively.

ntsysv
Configures run levels to set what services that should be started or stopped.

nwauth
Logs into a NetWare server. If no arguments are given, the user's .nvclient file is used.

nwbocreate
Creates a NetWare bindery object.

nwbols
Shows specified NetWare bindery objects that are visible for the user.

nwboprops
Shows all the properties of the specified NetWare bindery objects.

nwborm
Removes a NetWare bindery object.

nwbpadd
Specifies the value of a NetWare bindery property.

nwbpcreate
Creates the specified NetWare property.

nwbprm
Removes the specified NetWare bindery property.

nwbpset
Creates a Bindery property or configures the values.

nwbpvalues
Shows NetWare bindery property's contents.

nwdir
Shows files, directories, and their attributes from a NetWare directory.

nwfsctrl
Performs commands remotely on a NetWare server.

nwfsinfo
Shows some information about a NetWare server without logging in.

nwfstime
Shows or sets a NetWare server's date and time.

nwgrant
Adds a bindery object with the matching trustee rights to a directory.

nwmsg
Is called using kerneld when a NetWare server sends a broadcast message.

nwpasswd
Changes a user's password.

nwpurge
Permanently erases previously erased files.

nwrevoke
Revokes the specified NetWare bindery object with corresponding trustee rights from the directory.

nwrights
Asks a NetWare server for the effective rights in a file or directory for the user.

nwsfind
Searches for a NetWare server and locates a route to the server.

nwtrustee
Shows the trustee directories' assignments that a user has on a volume.

nwuserlist
Shows information about the users logged in to a NetWare server.

nwvolinfo
Shows information on a NetWare server volume.

objcopy
Copies object files using the GNU BFD Library.

objdump
Shows information about object files.

od
Reads a file from STDIN or from a specified file and exports the content to STDOUT in octal format.

odvitype
Checks and translate DVI files to human-readable form.

oldps
Shows process status information.

omega, iniomega, viromega
Converts extended Unicode TeX.

onintr
Specifies the shell will do with an interrupt. If option isn't given normal interrupt handle are restored.

openssl
Performs various cryptographic functions from the shell and can creates certificates.

openvt
Opens a new virtual terminal and runs the specified command with the arguments specified.

pack
Is a packing tool used for maintaining a packing list.

packf
Copies and formats messages from a folder into a file.

passmass
Lets you change passwords on many computers.

passwd
Changes login password and password attributes for the current or the specified user.

paste
Creates vertical columns of the content in the specified input files.

patch
Makes changes to files with patch files.

patch-metamail
Attempts to retrieve a patch from a server via FTP and install in the local metamail installation directory.

pathchk
Checks whether the file or files specified are valid or portable.

pcinitrd
Creates an initrd RAM disk image, which can be useful to boot the system from a PCMCIA device.

pclbanner
Prints a PCL banner on a fixed-size font printer.

perl
Is a programming language. Perl stands for Practical Extraction Report Language.

perlbug
Creates bug reports for perl.

perldoc
Finds and shows perl documentation from inside installations trees or scripts.

pfbtops
Converts a PostScript font in .pfb format into ASCII format.

pgrep
Searches for specific processes by using different criteria.

pg_ctl
Starst, stops, or restarts the postmaster.

pg_dump
Extracts a Postgres database into a script file.

pg_dumpall
Extracts all Postgres databases into a script file.

pg_passwd
Manipulates the flat password file for Postgres.

pg_upgrade
Allows upgrade from a previous release without reloading data.

pick
Filters messages through specified expressions.

ping
Sends ICMP echo requests to specified hosts. The remote host will, if it can, respond with a ICMP echo reply.

pinky
Shows information about users. Similar to finger.

pkill
Finds and kilsl processes by signaling it with the kill command.

pl2pm
Converts perl4 files to perl5 modules.

pmake
Compiles files depending on other files based on a makefile, and it does this in parallel mode.

pmap_set
Restarts a running portmapper or sets the list of registrated RPC programs on the local host. For restarting the portmapper you must redirect the output of pmap_dump to a file.

pnpdump
Dumps ISA Plug-and-Play device resource information to a specified file or STDOUT.

pnpprobe
Searches the ISA bus for Plug and Play sound cards.

pod2html
Converts pod to HTML files.

pod2latex
Converts Perl pod document files into LaTeX document files.

pod2man
Generates *roff input from a POD source which can then be shown on STDOUT using nroff or to a printer using troff.

pod2text
Converts POD files into formatted ASCII text files.

popd
Pops a directory from the directory stack and changes to it.

portmap
Converts RPC program numbers into DARPA protocol port numbers.

post
Delivers messages to local and remote users. Is the default program for send to use.

postgres
Runs a Postgres single-user backend.

postgresql-dump
Administers PostgreSQL when the database format is incompatible with an old version.

postmaster
Runs the Postgres multiuser backend.

poweroff
Writes pending information to disk, stops the processing and powers off the computer.

ppp-watch
Runs from within a ifup-ppp script that allows PPP interfaces to act like other interfaces.

pppd
Starts the Point to Point Protocol daemon.

pppdump
Converts PPP record file to readable format.

pppoe
Runs the user-space PPPoE client.

pppoe-server
Starts the user-space server for PPPoE

pppoe-sniff
Examines network for non-standard PPPoE frames.

pppstats
Shows PPP-related statistics for a PPP-interface. The statistics are shown since the last report.

pqlist
Shows print queues on a NetWare server.

pqrm
Removes print requests from a NetWare print queue.

pqstat
Shows the specified NetWare print queue, showing the jobs being processed.

pr
Filters printing and pagination, each input file/files are read, formatted and written to STDOUT.

praliases
Shows system mail aliases. If no key is specified all keys and their values are shown.

printenv
Shows the variable values in the environment.

printf
Interprets certain characters in the format string.

printmail
Shows all mails in your mailbox.

privatepw
Administers WU-FTPD group access file information.

proxymngr
Is the proxy manager service that determines client requests, keeping track of available and starting new proxies.

ps
Shows process ID, execution time, command name, terminal and other information about the active processes.

ps2ascii
Is a Ghostscript converter from PostScript or PDF to ASCII format.

ps2epsi
Converts a PostScript file and creates a new file in Adobe's Encapsulated PostScript Interchange format.

ps2pdf
Converts a PostScript file into a file in Adobe Portable Document Format.

psbanner
Prints a PostScript banner on a fixed-size font printer.

pserver
Connects to a NetWare server's print queues and sends the incoming print jobs to the Linux printing system.

psql
Starts Postgres interactive terminal.

pstree
Shows the current processes in a tree format.

pstruct, c2ph
Translates C to perl code (union and structure declarations).

pswrap
Creates wraps that send PostScript language code to the PostScript Interpreter.

ptx
Makes a permuted index of the specified file's contents.

pump
Is a network interface manager daemon working with the DHCP or BOOTP protocol.

pushd
Changes to a new working directory and places the current working directory into a direcory stack.

pwck
Verifies the integrity of password files.

pwconv
Modifies or creates the shadow password file /etc/shadow from the passwd password file.

pwd
Shows the absolute path to the current working directory.

pwunconv
Converts from shadow password file to standard passwd file.

quota
Shows the disk usage and limits for a user on mounted file systems.

quotacheck
Will check and update the quota for mounted file system.

quotaoff
Turns off disk quotas for file systems.

quotaon
Enables disk quotas for file systems.

raid0run
Starts up old RAID0 or LINEAR arrays.

raidstart
Starts existing RAID devices.

raidstop
Stops an existing RAID device.

ramsize
Sets the RAM disk size for the system, and is equivalent to rdev -r.

random
Snapshots a random state, then reloads that state at boot time a random number generator.

ranlib
Appends a table of contents to archive libraries so that they are linked faster.

rarp
Alters the information in the kernels RARP table.

raw
Binds a Linux raw character device.

rb
Will receive files using YMODEM, XMODEM, and ZMODEM protocols.

rc
Starts and stops services when the system runlevel changes.

rcp
Copies files between two computers. The computer can be local or remote.

rcs
Creates and or changes the attributes of RCS files.

rcsclean
Removes files based upon revision differences. If there is no difference, it removes the working file.

rcsdiff
Compares different versions of RCS files using the diff command.

rcsmerge
Merges two RCS files by finding the differences between them, then creating a new file.

rcvdist
Forwards mail to other addresses. It reads mail from STDIN.

rcvpack
Creates a copy of the message and saves it in the specified file.

rcvstore
Adds messages from STDIN into a mailbox folder.

rcvtty
Reports a new mail. Runs a command with the message as its STDIN, and shows the results on the screen.

rdate
Gets the time from a specified remote system and sets or shows it on the local system.

rdev
Shows or sets the root device for bootable Linux kernel images.

rdist
Distributes files from one computer to others. Will keep the owner, group, mode and modification times.

rdistd
Is used by the rdist command as a remote file distribution server program.

rdjpgcom
Shows the embedded comments in JPEG files.

read
Reads a line from STDIN.

readlink
Shows the destination name of a symbolic link.

readonly
Sets a variable read-only. If no name is given show all read-only variables.

readprofile
Shows kernel profile information to STDOUT in a three-column table if the profile buffer exists.

reboot
Restarts the operating system.

rec
Records audio.

red
Is a restricted version of ed and is often used to edit files automatically in a script.

refer, grefer
Finds and formats references as a preprocessor for nroff or troff.

rehash
Recalculates the internal hash table.

rename
Renames multiple files by replacing strings.

renice
Alters the priority of currently running processes.

repeat
Executes a command a specified number of times.

repquota
Shows the quota limit and the usage of the file systems.

reset
Restores a session's run-time parameters to default values.

resize
Shows current size of the xterm window and will set the TERMCAP settings to active window.

resize2fs
Resizes an ext2 file system on specified device altering the amount of blocks to size.

restore, rrestore
Restores files or file systems from a dump backup.

return
Reports from a shell function. If used outside a function it will function as exit.

rev
Reverses every line of a file or STDIN.

revnetgroup
Reverses the order of host and user listings in the network group /etc/netgroup file in NIS maps.

revpath
Generates a relative path.

rexec
Runs commands on a remote host.

rlog
Shows information about RCS files and log messages.

rlogin
Runs a remote login to a remote computer.

rm
Removes files and directories from the file system.

rmail
Administer received mail from remote hosts through basic networking utilities.

rmdir
Removes empty directories from the file system.

rmmod
Unloads specified loadable modules as long as they are not in use and not referred to by other modules.

rmt
Allows remote access to magnetic tape devices, normally started from a rexec or rcmd subroutine.

rootflags
Sets the flags used when mounting the root file system. Is the same as rdev –R.

rotatelogs
Starts a new log file and saves the old.

route
Manages and shows the routing tables on the host.

rpc.lockd
Starts the NFS lock manager (NLM). Useful for kernels that don't do this automatically.

rpc.rquotad
Is an RPC server that manages users of a local file system mounted over the NFS by reporting quotas.

rpc.rstatd
Returns statistics received from the kernel about performance.

rpc.rusersd
Is the user name server that lists users on the host.

rpc.rwalld
Is the rwall server that manages rwall requests. It is applied by using wall on all appropriate hosts.

rpc.statd
Performs passive monitoring of the server and implements the reboot notification service used by rpc.lockd that performs file lock recovery functions in the event the server is rebooted.

rpc.yppasswdd, yppasswdd
Handles the requests that comes from yppasswd to set new correct passwords.

rpc.ypxfrd
Transfers NIS maps from the master server to the slave server.

rpcgen
Creates C code to make an rpc protocol.

rpcinfo
Creates an RPC call to an RPC server and shows the information on what it finds.

rpm
Adds and removes software on a system. It's also used to create software packages.

rpm2cpio
Converts a Red Hat Package (RPM) file to a cpio archive on STDOUT.

rsh, remsh
Is a remote shell which is used to connect to a host and execute one specified command.

rstart
Executes programs on a remote computer using the Remote Execution Protocol.

rstartd
Is a script that helps the use of working with a remote shell.

rsync
Copies files from or to a remote site.

runlevel
Shows the previous and current system runlevel.

rup
Shows the status of machines on the network. Similar to uptime but for remote computers.

ruptime
Shows the status of machines on the network. Similar to uptime but for remote machines.

rusers
Lists users logged into the remote server. Similar to who but for remote servers.

rwho
Shows who is logged in to hosts on the local network.

rwhod, in.rwhod
Is a system status server for the programs rwho and ruptime.

rx
Will receive files using XMODEM protocol.

rz
Will receive files using ZMODEM protocol.

s2p
Converts a sed script to a perl script. The converted script will be shown on STDOUT.

sa1
Saves system activity int o the binary file /var/log/sa/sadd, where dd is the current day.

sa2
Saves system activity into the file /var/adm/sa/sardd where dd is the current day.

sadc
Saves system activity in binary format to a specified file.

samba
Manages samba smbd and nmdb daemons.

sar
Shows system utilization information earlier saved in files. Please see sadc to set up data collection.

sash
Is a stand-alone shell with many extra built-in commands.

sasldblistusers
Shows the users in the SASL password database (usually /etc/sasldb).

saslpasswd
Sets the SASL password for server programs.

sb
Sends files in batch using YMODEM or ZMODEM protocol.

scan
Gives a brief description of messages stored in the specified folder, or default folder if not specified.

scanpci
Shows information about your PCI bus.

sched
Is a simple scheduler used to run commands at a later time.

sclient
Is a Kerberos client. When connected to Kerberos server it returns a Kerberos authentication.

scp
Copies files in a secure way with all network traffic encrypted by ssh.

screen
Runs many programs on one terminal. Makes programs detached so they can be attached somewhere else.

screendump
Dumps the contents of the screen to STDOUT.

script
Records everything that is shown on the screen during a terminal session and saves the information into a file.

scsi
Administers PCMCIA SCSI adapters.

scsi_info
Shows information about SCSI-devices, such as addess parameters, device vendor information, etc.

sdiff
Compares the two files and shows the differences between them, side by side on the screen.

sed
Edits text files using a script of specified edit commands and shows the result.

select
Shows words as a menu on STDERR and $PS3 as a prompt wait for user input. Repeats until terminated.

send
Sends the specified letter files to it's destinations, defined in the message.

sendfiles
Sends multiple files via a MIME message.

sendmail
Is a mail router used to deliver mail messages locally or via the internet.

sessreg
Manages utmp/wtmp entries for xdm sessions.

set
Sets a shell variable to value. With no argument it shows all variables. In Bourne, Bash, Korn and Z-shell (sh, bash, ksh, zsh) set is used to set shell flags.

setclock
Sets the time for the hardware clock.

setenv
Sets an environment variable. With no argument it shows all environment variables.

setfdprm
Is a utility to set and change parameters on auto-detecting floppy devices.

setleds
Sets the status flags for the keyboard LED's. Shows current status if no option is specified.

setpci
Is used to query and configure PCI devices. All numbers are entered in hexadecimal values.

setquota
Sets the specified quota for a user or a group from the command line.

setserial
Sets or retrieve serial port information.

setsid
Runs the specified program in a new session.

settc
Makes the shell believe that the terminal capability has the specified value.

setterm
Sets terminal attributes.

setty
Sets which tty modes the shell allows to be changed.

setup
Configures the system in interactive mode.

setvar
Sets variable to value.

setxkbmap
Sets the keyboard layout by means of the X keyboard extension.

sfdisk
Administers partition tables.

shar
Converts binary files to a text friendly archive.

shift
Shifts the command line argument one (or number) step to the left.

shopt
Alters optional shell variables controlling the behavior of the shell.

show
Shows specified messages or folders. This is part of the NMH package.

showaudio
Plays an audio email message on your workstation.

showfont
Shows information from the X font server about a specified font.

showmount
Shows all clients that have remote mounts from a server.

showrgb
Converts a compiled RGB color name database back to the original form.

shred
Erases files by overwriting them repeatedly. Which makes it very hard to restore the information.

shutdown
Changes the current run level. Most often to shut the system down.

size
Shows segment or section size information for each loaded section in object files.

skill
Kills processes. Combines features from kill and killall.

slattach
Transfers a serial line connection to a network interface.

sleep
Puts the system to sleep for a period of time.

slist
Shows all NetWare servers present on the network.

slocal
Processes inbound messages according to a selection criterion.

slocate, locate
Looks quickly in a database in order to find files.

smbadduser
Adds users to SMB’s password file.

smbclient
Connects to a remote service using SMB.

smbd
Starts the Samba daemon that handles SMB/CIFF requests.

smbmnt
Mounts SMB file system shares. Checks if a user has write permissions on the mount point before mounting.

smbmount
Mounts an SMB file system.

smbpasswd
Changes the user's SMB password.

smbspool
Sends a print file to an SMB printer.

smbstatus
Shows the current Samba connections.

smbtar
This command script is a utility that dumps SMB shares into a tape device.

smbumount
Lets users unmount their SMB mounted directories. The directory must have the SUID set to root.

smproxy
Works as an X application proxy and allows the application to use an X11R6 session.

smrsh
Restricts users to only be able to run certain sendmail commands in a shell.

sndAppleSingle
Allows the user to send Macintosh files stored inside a UNIX file system with the CAP AUFS program.

sndconfig
Is a graphic interface program that configures sound cards to work with a Linux kernel module.

snice
Shows process status and sets new priorities for processes.

snmpbulkget
Communicates with a network entity using SNMP BULK requests.

snmpbulkwalk
Communicates with a network entity using SNMP BULK requests.

snmpd
Is an agent that responds to SNMP request packets. Monitors networks.

snmpdelta
Monitors deltas of integer-valued SNMP variables.

snmpget
Communicates with a network entity using SNMP GET requests.

snmpgetnext
Communicates with a network entity using SNMP GET NEXT requests.

snmpnetstat
Shows network status using SNMP.

snmpset
Communicates with a network entity using SNMP SET requests.

snmpstatus
Retrieves important information from a network host.

snmptable
Shows SNMP tables after retrieving them.

snmptest
Communicates with a network entity using SNMP requests.

snmptranslate
Translates SNMP objects into more useful information.

snmptrap
Sends an SNMP TRAP to a manager.

snmptrapd
Receives and logs SNMP trap messages.

snmpusm
Administers SNMPv3 users on a remote entity.

snmpwalk
Communicates with a network entity using SNMP GET next requests.

soelim
Determines and excludes the .so requests from either troff or nroff input.

sort
Sorts and merges lines from the specified files or from STDIN, and prints them to STDOUT.

source
Reads commands form a file and runs them in the current shell.

spell
Is a capability script for the aspell spell checker.

split
Splits a file into a set of smaller files. The output files will get a double letter extension (.aa, .ab, .ac ... ).

splitmail
Splits an e-mail into smaller pieces according to proposed Internet standard for multimedia mail formats.

spost
Delivers a message.

sserver
Is a Kerberos server application. When there is a connection it, returns a Kerberos principal.

ssh, slogin
Logins secure to a remote computer. It's intended to replace rlogin.

ssh-add
Administrates RSA identities for the SSH authentication agent.

ssh-agent
Holds private keys for RSA authentication.

ssh-keygen
Is used it create public and private SSH keys.

sshd
Is the secure shell deamon that allows ssh clients access the computer.

startx
Starts a single session of the X-window system. Is a front end to xinit.

stat
Shows information on the specified files of file systems.

statserial
Shows information about the specified serial port. Useful to debug modems and ports.

stinit
Initializes SCSI magnetic tape drives.

stop
Stops a process.

strace
Records all system calls sent and received by the processes within the specified command.

strfile
Creates a random access file for saving strings. Lines are separated by the delimiting character.

strings
Searches for printable strings in object or binary files.

strip
Strips the symbol table and the information about debugging and line numbers from an object file.

stty
Alters the options for a terminal.

stunnel
Makes it possible to use SSL-enabled connections between two computers, using non-SSL-enabled daemons.

su
Switches to another user in the current session.

suexec
Switches the user when executing an external application through programs that are used internally by Apache.

suidperl
Executes a perl script in suID mode.

sulogin
Prompts for the root password to enter single-user mode, or to press Ctrl-D to proceed with normal startup.

sum
Shows a 16-bit checksum and a 512 byte block count for a file.

SuperProbe
Finds installed video hardware, used by some X11 configuration software to determine configurations.

suspend
Stops the current shell as if Ctrl-Z has been pressed. Login shell can't be stopped.

swapdev
Sets the kernel's swap device. Shows usage information if run without parameters. Is the equivalent of rdev –s.

swapoff
Disables swapping on the specified devices.

swapon
Specifies a device to start swap or page on.

swat
Configures Samba over the web. Short for Samba Web Administration Tool. Is run from xinetd.

switch, breaksw
Matches each pattern successively against the word and runs the commands when the first match is found.

switchdesk
Is used to switch between various desktop environments like GNOME, KDE and AnotherLevel.

switchdesk-helper
Specifies what window manager to run when starting X.

sx
Sends files using XMODEM protocol

sync
Flushs all unwritten file system buffers to disk.

sys-unconfig
Resets the system configuration. The file /.unconfigured tells the system to run the programs to configure system.

sysctl
Configures kernel parameters at runtime - the parameters is listed in /proc/sys/.

sysklogd
Is a system logging utility.

syslogd
Logs system messages and saves it into a file.

sz
Sends files using ZMODEM protocol.

tac
Shows files in reverse order. The opposite of cat.

tail
Shows the tail end of the file specified to STDOUT. Shows the last 10 entries by default.

tailf
Shows the growth of a file.

talk
Is used to talk to another user, using the terminal.

talkd, in.talkd, in.ntalkd, ntalkd
Provides the server function for the talk command. Usually started by the Internet Server.

tangle
Converts a WEB file to Pascal.

tar
Extracts or creates files from or to a tar file, tape by default but can be any media or file.

tbl
Formats tables before to use them in nroff or troff. For BSD and Linux it is only used for troff.

tc
Creates and associate queues with output devices.

tclsh
Is the Tool command language (Tcl) shell.

tcpd
Controls and logs incoming requests for Internet services. Used from inetd.

tcpdchk
Checks your TCP wrapper configuration and reports all potential problems it can find.

tcpdmatch
Predicts how the TCP wrapper would handle a specific request for service.

tcpdump
Shows the headers of packets on a network interface.

tcsh
Is a enchanced version of the C-shell that is completely compatible.

tee
Copies STDIN to STDOUT as well as to files.

telesctrl
Configures the log level of the HiSax-ISDN device driver. Log information is stored in /dev/isdnctrl.

telltc
Shows the current values of all terminal capabilities.

telnet, tn
Uses the telnet protocol to communicate with other hosts.

test
Evaluates conditions. In if structures conditions are often used inside brackets ( [ ] ).

testparm
Reads a Samba configuration file to check whether it is correct.

testprns
Checks whether a given printer name is valid to use with smbd.

tex, initex, virtex
Formats text and typesetting.

texindex
Creates an index for a TeX output file.

tfmtodit
Creates groff font files to use with groff -Tdvi.

tftp
Sends files to and from a remote host using the Trivial File Transfer Protocol (TFTP).

thumbnail
Creates a TIFF image file with thumbnail images.

tic
Compiles a terminfo file. The data is saved in the directory /usr/share/lib/terminfo for AIX and Solaris and in the directory /usr/share/terminfo for BSD and Linux.

tie
Merges or applies WEB system change files.

tiff2bw
Converts a color TIFF image to grayscale.

tiff2ps
Converts TIFF images to PostScript format.

tiffcmp
Compares two TIFF files.

tiffcp
Merges TIFF images together into a single multi-image file.

tiffdither
Converts an 8-bit grayscale TIFF image to a bilevel TIFF image.

tiffinfo
Shows information about TIFF files.

tiffsplit
Creates single-image files from a multi-image TIFF file.

time
Starts a program and shows statistics on STDERR about how long it took to run.

timeconfig
Configures the computer time in a ncurses-based environment.

times
Shows accumulated system and user times for processes run from the shell..

tin
Is a Usenet news reader, which can read locally or remotely via an NNTP server.

tload
Shows system load as a graph.

tmpwatch
Erases files that haven't been accessed for a specified number of hours.

toe
Shows a list of all available terminal types by primary name with their descriptions.

top
Shows a list of the most active CPU processes.

touch
Gives the file specified a new time and date stamp. If the file does not exist it will be created.

tput
This utility is used to initialize a terminal or query a terminfo database.

tr
Replaces or deletes characters while copying from STDIN to STDOUT.

tracepath
Shows the path, and the MTU that is found on the way, to the specified destination.

traceroute
Shows you a list of the route a packets takes to reach a network host.

trap
Runs the command when the shell receive signal. If command is a null string ("") it will reset the signals to there original behavior. Used alone it shows all traps.

troff, gtroff
Formats the text in the specified file for printing or typesetting.

true
Provides a true value in scripts, does nothing but always exits with a value of 0.

tset
Determines and configures your terminal.

tsort
Sorts items from a text file or STDIN and show on STDOUT an ordered listing of the items.

tty
Shows the terminal that is used as STDIN.

tune2fs
Alters tunable file system parameters on second extended file systems.

tunelp
Configures various parameters for the lp device.

twm
Is a X-window manager that provides icon management, macros, key bindings, title bars and shaped windows.

type
Shows a description of a commands type.

typeset, declare
Sets values and attributes for variables. A new variable instance is created when used inside functions.

tzselect
Configures the time zone in an interactive mode.

ul
Reads STDIN or specified files and alter the underscore characters to fit your terminal.

ulimit
Sets and shows the size limits used by the shell and its child processes. Shows the current limit if not given.

umask
Alters the file mode creation mask of the current shell execution environment.

umount, unmount
Unmounts local or remote file systems. AIX also have a unmount command with the same syntax.

unalias
Erases the definitions of all aliases specified on the command line from the current shell execution environment.

uname
Shows information about the current system.

unbuffer
Disables the output buffering when the specified program is redirected.

uncomplete
Removes any pattern specified with complete.

uncompress
Uncompresses .Z files. Removes the .Z suffix when it is done.

unexpand
Replaces the spaces in text files created with expand back to Tab characters.

unhash
Disables the internal hash table. In zsh it will remove names from the internal hash table.

unicode_start
Sets Unicode mode to the screen and keyboard.

unicode_stop
Takes screen and keyboard out of Unicode mode and into 8-bit mode.

uniq
Filters out adjacent lines that are alike and shows the output on STDOUT or save it to a file.

unlimit
Removes resource limits. If no options is specified all limits will be erased.

unset
Removes variable or function from the shell.

unsetenv
Removes environment variables.

unshar
Searches mail messages for shell archives, unpacks them, and saves them in a single file.

unstr
Shows the strings from a file created by the strfile command.

until
Repeats the commands until expression is true.

unzip
Uncompress, list, test, or show the compressed files from a zip archive.

unzipsfx
Creates self-extracting zip archives. Is a binary stub to be added to existing zip archives.

up2date
Updates packets installed on your computer.

update
Tells the kernel daemon to flush dirty buffers back to disk (also known as bdflush).

updatedb
Is a utility to update the slocate database.

uptime
Shows how long the system has been up, number of users and the load average for the last 1, 5 and 15 minutes.

urlview
Reads all URLs it can find in a file and shows them in an interactive menu.

useradd, adduser
Creates a new user or updates default new user information.

userconf
Configures system accounts and groups interactively or on the command line.

userdel
Erases a user's account from the system.

userhelper
Is a interface to pam that is used to alter the user's shell, password, and GECOS information.

userinfo
Alters the user's finger information just like the command chfn, but does so interactively.

usermod
Alters a specified user's login account permissions and memberships on the system.

usermount
Starts a graphical tool to mount, unmount, and format file systems.

usernetctl
Changes the status of the specified network interface.

userpasswd
Is a graphical tool that lets users change their passwords.

users
Shows a one-line list of the users who are logged in on the system.

usleep
Sleeps for some number of microseconds.

uudecode
Decodes an encoded file created by uuencode. The decoded file name is set by uuencode.

uuencode
Creates an encoded file to use when you send mail.

uuidgen
Creates a new UUID value.

vacuumdb
Cleans your Postgres database. The Postgres query optimizer uses it to generate internal statistics.

vdir
Shows information about the current or the specified directory.

vi, view
Edits or views text files.

vidmode
Sets video mode for a kernel image. Is equivalent to rdev -v.

viewres
Shows a tree structure of the widget class hierarchy of the Athena Widget Set.

vigr
Is used to edit the /etc/group file.

vimtutor
Shows a help page on how to start using the very powerful editor vim in Linux.

vipw
Edits the /etc/passwd file.

vmstat
Shows various statistics for the system. For example memory and io usages.

vt-is-UTF8
Checks whether current VT is in UTF8- or byte mode.

w
Shows information about logged in users.

wait
Waits for a background process to complete. C and TC-Shell will wait for all background processes.

wall
Shows a message to all currently logged in users.

watch
Runs a specified command several times to show the change of the output

wc
Counts characters, words, and lines in files.

weave
Translates a file from .web style to a TeX style file.

whatis
Shows the header line from the manual page for a command.

whatnow
Is used as a front end for the nmh commands to prompt the user of what to do.

where
Shows where a command is located, including alias, Internal, and in the path.

whereis
Searches binary, source and manual page files for the specified command.

which
Shows the path to a command.

while
Repeats the commands while the expression is true.

who
Shows who is on the system.

who am i
Is actually the who command but only shows the current user. It takes two arguments that can be anything.

whoami
Shows the login name of the current effective user.

whois
Finds names or handles for an internet domain name.

wish
Specifies the Tool command language with a graphic tool kit (Tcl/Tk) used to run Tcl/Tk scripts in graphic mode.

wnewmail
Alerts you when a new mail arrives.

word-list-compress
Compresses or decompresses word list files read from STDIN and output on STDOUT.

write
Writes to another user's screen. The messages is read from the console. Can be used to reply in AIX.

writevt
Inserts a text string in a terminal's input buffer.

wrjpgcom
Inserts text information into a JPEG picture.

wvdial
Dials a modem and initiates PPP. Configured from command line or from the file /etc/wvdial.conf.

wvdialconf
Detects your modem and its attributes, then updates the /etc/wvdial.conf file.

X
Is the X-window system which is a network-transparent GUI system developed by X Consortium, Inc. This is used with bitmap display systems and manages user input to and from various programs.

x11perf
Measures the performance of an X server.

x11perfcomp
Compares and shows the difference between x11servers

xargs
Creates a list of arguments, start a program and run the arguments.

xauth
Manages the authorization rules used when connecting to a X-server.

Xconfigurator
Configures the XFree86 server.

xconsole
Shows console messages with X.

xf86config
Is a console-based application to configure the XF86Config file.

xfindproxy
Finds proxy services to be used with a proxy manager.

XFree86
Is a free X server that is delivered with several Linux distributions.

xfs
Supplies fonts to X-Window servers.

xfwp
Is an X firewall proxy. Provides an application layer firewall for X traffic.

xgetfile
Is a file manager based on X-window.

xgettext
Creates portable message files that contains copies of C strings that are found in ANSI C source code.

xhost
Controls access to the X server by keeping a list of allowed hosts and users.

xinetd
Monitors service ports and starts the required services when the requests comes.

xinit
Starts the the X-Window server specified.

xisdnload
Shows periodically updated information about the ISDN load average.

xkbevd
Monitors for XKB events and runs the requested commands when they occur.

xkibitz
Allows many people to interact with each others' programs.

xkill
Kills an X client. Useful for removing problematic programs.

xload
Shows a histogram over the average system load.

xlsatoms
Shows the specified interned atoms on the server.

xlsclients
Shows client applications that run on a screen.

xlsfonts
Lists X Window fonts that match a specified pattern.

xmag
Enlarges parts of the screen.

xman
Shows man pages in a browser when running X.

xmkmf
Converts an Imakefile to a Makefile.

xmodmap
Shows and modify the keymaps in X.

xmonisdn
Shows the status of ISDN network connections and enables the starting or stopping of subsystems.

xmorph
Morphs images in an X window environment.

xon
Executes the specified command on the specified remote host.

xplaycd
Plays audio CD-ROMs interactively.

xrdb
Contains resources for the X server. This program normally runs from an X startup file.

xrefresh
Refreshes all or part of an X screen.

xset
Sets the user options for the X display. Such as mouse, bell, keys and much more.

xsetmode
Sets the mode for an input device under X window.

xsetpointer
Sets the main pointer for X window.

xsetroot
Modifies how to view the background window on a workstation that runs X.

xsm
Manages X sessions. Allows applications to run and lets them become part of the session.

xterm
Is a terminal emulator for X-Window. Provides terminal emulation for programs that can't use X-Window.

xwd
Saves window images into a dump file.

xwininfo
Shows information about windows.

xwud
Shows an image dump that is saved in a formatted dump file.

xxd
Converts binary files or STDIN to a hexadecimal file, or vice versa.

yacc, byacc
Converts a file containing grammar rules into a C-source file name y.tab.c.

yes
Shows the command-line arguments, separated by spaces and new lines forever.

ypbind
Runs at startup and keeps information about the bindings between NIS clients and servers.

ypcat
Shows the values in the specified NIS map.

ypchfn
Changes the users GECOS field, where full name and user-related information exist.

ypchsh
Alters the users default shell in the NIS database.

ypdomainname
Shows or sets the system's NIS/YP domain name.

ypinit
Sets up an NIS server or client system.

ypmatch
Shows the values of keys from a NIS map.

yppasswd
Alters the yellow pages password in the NIS database.

yppasswdd
A script that executes the rpc.yppasswdd that makes it easier to control the daemon.

yppoll
Uses ypserv to get the version number and master NIS server for the specified map.

yppush
Copies a new NIS map from the master server to the slave servers.

ypserv
Is a NIS server daemon that looks up information requested by other yp commands.

ypset
Tells ypbind to use the specified server for NIS services.

ypwhich
Shows the name of the NIS server that provides the name services to a NIS client.

ypxfr
Manages NIS map transfers between a NIS server and a host.

zcat
Uncompresses a list of files from the command line or STDIN, then writes to STDOUT.

zcmp
Compares two compressed files. Return status is 0 = identical, 1 = different, 1 < error.

zdiff
Compares compressed files. It uses the command diff to run the comparison.

zdump
Shows the current date and time for the time zones that you specify on the command line.

zforce
Adds a .gz extension to a compressed (gzip) file. Useful for files with names truncated after a file transfer.

zgrep, zfgrep, zegrep
Searches for text strings inside compressed files.

zic
Creates files that can be used for time conversion.

zip
Compresses files.

zipcloak
Is used for encryption or decryption of a compressed file.

zipgrep
Searches for text strings inside zip archive files.

zipinfo
Shows technical information about a zip archive.

zipnote
Inserts notes and comments into zip files.

zipsplit
Splits one zip file into many zip files.

zless
Enables compressed text files to be inspected one full screen at a time.

zmore
Shows compressed text files one screen at a time.

znew
Recompresses a .Z compressed file to a .gz file.

Other articles in this Category