· 8 years ago · Apr 22, 2018, 05:42 AM
1The descriptions of these Linux commands are based on their manual pages. To access the man page:
2
3man command_name
4
5For eg: man cat
6
7If you find any discrepancy, please feel free to contact for any correction.
8Linux Commands – A
9Command Description
10accept Accept or Reject jobs to a destination, such as a printer.
11access Check a user’s RWX permission for a file.
12aclocal GNU autoconf too
13aconnect ALSA sequencer connection manager.
14acpi Show information about the Advanced Configuration and Power Interface.
15acpi_available Check if ACPI functionality exists on the system.
16acpid Informs user-space programs about ACPI events.
17addr2line Used to convert addresses into file names and line numbers.
18addresses Formats for internet mail addresses.
19agetty An alternative Linux Getty
20alias Create an alias for Linux commands
21alsactl Access advanced controls for ALSA soundcard driver.
22amidi Perform read/write operation for ALSA RawMIDI ports.
23amixer Access CLI-based mixer for ALSA soundcard driver.
24anacron Used to run commands periodically.
25aplay Sound recorder and player for CLI.
26aplaymidi CLI utility used to play MIDI files.
27apm Show Advanced Power Management (APM) hardware info on older systems.
28apmd Used to handle events reported by APM BIOS drivers.
29apropos Shows the list of all man pages containing a specific keyword
30apt Advanced Package Tool, a package management system for Debian and derivatives.
31apt-get Command-line utility to install/remove/update packages based on APT system.
32aptitude Another utility to add/remove/upgrade packages based on the APT system.
33ar A utility to create/modify/extract from archives.
34arch Display print machine hardware name.
35arecord Just like aplay, it’s a sound recorder and player for ALSA soundcard driver.
36arecordmidi Record standard MIDI files.
37arp Used to make changes to the system’s ARP cache
38as A portable GNU assembler.
39aspell An interactive spell checker utility.
40at Used to schedule command execution at specified date & time, reading commands from an input file.
41atd Used to execute jobs queued by the at command.
42atq List a user’s pending jobs for the at command.
43atrm Delete jobs queued by the at command.
44audiosend Used to send an audio recording as an email.
45aumix An audio mixer utility.
46autoconf Generate configuration scripts from a TEMPLATE-FILE and send the output to standard output.
47autoheader Create a template header for configure.
48automake Creates GNU standards-compliant Makefiles from template files
49autoreconf Update generated configuration files.
50autoscan Generate a preliminary configure.in
51autoupdate Update a configure.in file to newer autoconf.
52awk Used to find and replace text in a file(s).
53Linux Commands – B
54Command Description
55badblocks Search a disk partition for bad sectors.
56banner Used to print characters as a poster.
57basename Used to display filenames with directoy or suffix.
58bash GNU Bourne-Again Shell.
59batch Used to run commands entered on a standard input.
60bc Access the GNU bc calculator utility.
61bg Send processes to the background.
62biff Notify about incoming mail and sender’s name on a system running comsat server.
63bind Used to attach a name to a socket.
64bison A GNU parser generator, compatible with yacc.
65break Used to exit from a loop (eg: for, while, select).
66builtin Used to run shell builtin commands, make custom functions for commands extending their functionality.
67bzcmp Used to call the cmp program for bzip2 compressed files.
68bzdiff Used to call the diff program for bzip2 compressed files.
69bzgrep Used to call grep for bzip2 compressed files.
70bzip2 A block-sorting file compressor used to shrink given files.
71bzless Used to apply ‘less’ (show info one page at a time) to bzip2 compressed files.
72bzmore Used to apply ‘more’ (an inferior version of less) to bzip2 compressed files.
73Linux Commands – C
74Command Description
75cal Show calendar.
76cardctl Used to control PCMCIA sockets and select configuration schemes.
77cardmgr Keeps an eye on the added/removes sockets for PCMCIA devices.
78case Execute a command conditionally by matching a pattern.
79cat Used to concatenate files and print them on the screen.
80cc GNU C and C++ compiler.
81cd Used to change directory.
82cdda2wav Used to rip a CD-ROM and make WAV file.
83cdparanoia Record audio from CD more reliably using data-verification algorithms.
84cdrdao Used to write all the content specified to a file to a CD all at once.
85cdrecord Used to record data or audio compact discs.
86cfdisk Show or change the disk partition table.
87chage Used to change user password information.
88chattr Used to change file attributes.
89chdir Used to change active working directory.
90chfn Used to change real user name and information.
91chgrp Used to change group ownership for file.
92chkconfig Manage execution of runlevel services.
93chmod Change access permission for a file(s).
94chown Change the owner or group for a file.
95chpasswd Update password in a batch.
96chroot Run a command with root privileges.
97chrt Alter process attributed in real-time.
98chsh Switch login shell.
99chvt Change foreground virtual terminal.
100cksum Perform a CRC checksum for files.
101clear Used to clear the terminal window.
102cmp Compare two files (byte by byte).
103col Filter reverse (and half-reverse) line feeds from the input.
104colcrt Filter nroff output for CRT previewing.
105colrm Remove columns from the lines of a file.
106column A utility that formats its input into columns.
107comm Used to compare two sorted files line by line.
108command Used to execute a command with arguments ignoring shell function named command.
109compress Used to compress one or more file(s) and replacing the originals ones.
110continue Resume the next iteration of a loop.
111cp Copy contents of one file to another.
112cpio Copy files from and to archives.
113cpp GNU C language processor.
114cron A daemon to execute scheduled commands.
115crond Same work as cron.
116crontab Manage crontab files (containing schedules commands) for users.
117csplit Split a file into sections on the basis of context lines.
118ctags Make a list of functions and macro names defined in a programming source file.
119cupsd A scheduler for CUPS.
120curl Used to transfer data from or to a server using supported protocols.
121cut Used to remove sections from each line of a file(s).
122cvs Concurrent Versions System. Used to track file versions, allow storage/retrieval of previous versions, and enables multiple users to work on the same file.
123Linux Commands – D
124Command Description
125date Show system date and time.
126dc Desk calculator utility.
127dd Used to convert and copy a file, create disk clone, write disk headers, etc.
128ddrescue Used to recover data from a crashed partition.
129deallocvt Deallocates kernel memory for unused virtual consoles.
130debugfs File system debugger for ext2/ext3/ext4
131declare Used to declare variables and assign attributes.
132depmod Generate modules.dep and map files.
133devdump Interactively displays the contents of device or file system ISO.
134df Show disk usage.
135diff Used to compare files line by line.
136diff3 Compare three files line by line.
137dig Domain Information Groper, a DNS lookup utility.
138dir List the contents of a directory.
139dircolors Set colors for ‘ls’ by altering the LS_COLORS environment variable.
140dirname Display pathname after removing the last slash and characters thereafter.
141dirs Show the list of remembered directories.
142disable Restrict access to a printer.
143dlpsh Interactive Desktop Link Protocol (DLP) shell for PalmOS.
144dmesg Examine and control the kernel ring buffer.
145dnsdomainname Show the DNS domain name of the system.
146dnssec-keygen Generate encrypted Secure DNS keys for a given domain name.
147dnssec-makekeyset Produce domain key set from one or more DNS security keys generated by dnssec-keygen.
148dnssec-signkey Sign a secure DNS keyset with key signatures specified in the list of key-identifiers.
149dnssec-signzone Sign a secure DNS zonefile with the signatures in the specified list of key-identifiers.
150doexec Used to run an executable with an arbitrary argv list provided.
151domainname Show or set the name of current NIS (Network Information Services) domain.
152dosfsck Check and repair MS-DOS file systems.
153du Show disk usage summary for a file(s).
154dump Backup utility for ext2/ext3 file systems.
155dumpe2fs Dump ext2/ext3/ext4 file systems.
156dumpkeys Show information about the keyboard driver’s current translation tables.
157Linux Commands – E
158Command Desription
159e2fsck Used to check ext2/ext3/ext4 file systems.
160e2image Store important ext2/ext3/ext4 filesystem metadata to a file.
161e2label Show or change the label on an ext2/ext3/ext4 filesystem.
162echo Send input string(s) to standard output i.e. display text on the screen.
163ed GNU Ed – a line-oriented text editor.
164edquota Used to edit filesystem quotas using a text editor, such as vi.
165egrep Search and display text matching a pattern.
166eject Eject removable media.
167elvtune Used to set latency in the elevator algorithm used to schedule I/O activities for specified block devices.
168emacs Emacs text editor command line utility.
169enable Used to enable/disable shell builtin commands.
170env Run a command in a modified environment. Show/set/delete environment variables.
171envsubst Substitute environment variable values in shell format strings.
172esd Start the Enlightenment Sound Daemon (EsounD or esd). Enables multiple applications to access the same audio device simultaneously.
173esd-config Manage EsounD configuration.
174esdcat Use EsounD to send audio data from a specified file.
175esdctl EsounD control program.
176esddsp Used to reroute non-esd audio data to esd and control all the audio using esd.
177esdmon Used to copy the sound being sent to a device. Also, send it to a secondary device.
178esdplay Use EsounD system to play a file.
179esdrec Use EsounD to record audio to a specified file.
180esdsample Sample audio using esd.
181etags Used to create a list of functions and macros from a programming source file. These etags are used by emacs. For vi, use ctags.
182ethtool Used to query and control network driver and hardware settings.
183eval Used to evaluate multiple commands or arguments are once.
184ex Interactive command
185exec An interactive line-based text editor.
186exit Exit from the terminal.
187expand Convert tabs into spaces in a given file and show the output.
188expect An extension to the Tcl script, it’s used to automate interaction with other applications based on their expected output.
189export Used to set an environment variable.
190expr Evaluate expressions and display them on standard output.
191Linux Commands – F
192Command Description
193factor Display prime factors of specified integer numbers.
194false Do nothing, unsuccessfully. Exit with a status code indicating failure.
195fc-cache Make font information cache after scanning the directories.
196fc-list Show the list of available fonts.
197fdformat Do a low-level format on a floppy disk.
198fdisk Make changes to the disk partition table.
199fetchmail Fetch mail from mail servers and forward it to the local mail delivery system.
200fg Used to send a job to the foreground.
201fgconsole Display the number of the current virtual console.
202fgrep Display lines from a file(s) that match a specified string. A variant of grep.
203file Determine file type for a file.
204find Do a file search in a directory hierarchy.
205finger Display user data including the information listed in .plan and .project in each user’s home directory.
206fingerd Provides a network interface for the finger program.
207flex Generate programs that perform pattern-matching on text.
208fmt Used to convert text to a specified width by filling lines and removing new lines, displaying the output.
209fold Wrap input line to fit in a specified width.
210for Expand words and run commands for each one in the resultant list.
211formail Used to filter standard input into mailbox format.
212format Used to format disks.
213free Show free and used system memory.
214fsck Check and repair a Linux file system
215ftp File transfer protocol user interface.
216ftpd FTP server process.
217function Used to define function macros.
218fuser Find and kill a process accessing a file.
219Linux Commands – G
220Command Description
221g++ Run the g++ compiler.
222gawk Used for pattern scanning and language processing. A GNU implementation of AWK language.
223gcc A C and C++ compiler by GNU.
224gdb A utility to debug programs and know about where it crashes.
225getent Shows entries from Name Service Switch Libraries for specified keys.
226getkeycodes Displays the kernel scancode-to-keycode mapping table.
227getopts A utility to parse positional parameters.
228gpasswd Allows an administrator to change group passwords.
229gpg Enables encryption and signing services as per the OpenPGP standard.
230gpgsplit Used to split an OpenPGP message into packets.
231gpgv Used to verify OpenPGP signatures.
232gpm It enables cut and paste functionality and a mouse server for the Linux console.
233gprof Shows call graph profile data.
234grep Searches input files for a given pattern and displays the relevant lines.
235groff Serves as the front-end of the groff document formatting system.
236groffer Displays groff files and man pages.
237groupadd Used to add a new user group.
238groupdel Used to remove a user group.
239groupmod Used to modify a group definition.
240groups Show the group(s) to which a user belongs.
241grpck Verifies the integrity of group files.
242grpconv Creates a gshadow file from a group or an already existing gshadow.
243gs Invokes Ghostscript, and interpreter and previewer for Adobe’s PostScript and PDF languages.
244gunzip A utility to compress/expand files.
245gzexe Used compress executable files in place and have them automatically uncompress and run at a later stage.
246gzip Same as gzip.
247Linux Commands – H
248Command Description
249halt Command used to half the machine.
250hash Shows the path for the commands executed in the shell.
251hdparm Show/configure parameters for SATA/IDE devices.
252head Shows first 10 lines from each specified file.
253help Display’s help for a built-in command.
254hexdump Shows specified file output in hexadecimal, octal, decimal, or ASCII format.
255history Shows the command history.
256host A utility to perform DNS lookups.
257hostid Shows host’s numeric ID in hexadecimal format.
258hostname Display/set the hostname of the system.
259htdigest Manage the user authentication file used by the Apache web server.
260htop An interactive process viewer for the command line.
261hwclock Show or configure the system’s hardware clock.
262Linux Commands – I
263Command Description
264iconv Convert text file from one encoding to another.
265id Show user and group information for a specified user.
266if Execute a command conditionally.
267ifconfig Used to configure network interfaces.
268ifdown Stops a network interface.
269ifup Starts a network interface.
270imapd An IMAP (Interactive Mail Access Protocol) server daemon.
271import Capture an X server screen and saves it as an image.
272inetd Extended internet services daemon, it starts the programs that provide internet services.
273info Used to read the documentation in Info format.
274init Systemd system and service manager.
275insmod A program that inserts a module into the Linux kernel.
276install Used to copy files to specified locations and set attributions during the install process.
277iostat Shows statistics for CPU, I/O devices, partitions, network filesystems.
278ip Display/manipulate routing, devices, policy, routing and tunnels.
279ipcrm Used to remove System V interprocess communication (IPC) objects and associated data structures.
280ipcs Show information on IPC facilities for which calling process has read access.
281iptables Administration tool for IPv4 packet filtering and NAT.
282iptables-restore Used to restore IP tables from data specified in the input or a file.
283iptables-save Used to dump IP table contents to standard output.
284isodump A utility that shows the content iso9660 images to verify the integrity of directory contents.
285isoinfo A utility to perform directory like listings of iso9660 images.
286isosize Show the length of an iso9660 filesystem contained in a specified file.
287isovfy Verifies the integrity of an iso9660 image.
288ispell A CLI-based spell-check utility.
289Linux Commands – J
290Command Description
291jobs Show the list of active jobs and their status.
292join For each pair of input lines, join them using a command field and display on standard output.
293Linux Commands – K
294Command Description
295kbd_mode Set a keyboard mode. Without arguments, shows the current keyboard mode.
296kbdrate Reset keyboard repeat rate and delay time.
297kill Send a kill (termination) signal to one more processes.
298killall Kills a process(es) running a specified command.
299killall5 A SystemV killall command. Kills all the processes excluding the ones which it depends on.
300klogd Control and prioritize the kernel messages to be displayed on the console, and log them through syslogd.
301kudzu Used to detect new and enhanced hardware by comparing it with existing database. Only for RHEL and derivates.
302Linux Commands – L
303Command Description
304last Shows a list of recent logins on the system by fetching data from /var/log/wtmp file.
305lastb Shows the list of bad login attempts by fetching data from /var/log/btmp file.
306lastlog Displays information about the most recent login of all users or a specified user.
307ld The Unix linker, it combines archives and object files. It then puts them into one output file, resolving external references.
308ldconfig Configure dynamic linker run-time bindings.
309ldd Shows shared object dependencies.
310less Displays contents of a file one page at a time. It’s advanced than more command.
311lesskey Used to specify key bindings for less command.
312let Used to perform integer artithmetic on shell variables.
313lftp An FTP utility with extra features.
314lftpget Uses lftop to retrieve HTTP, FTP, and other protocol URLs supported by lftp.
315link Create links between two files. Similar to ln command.
316ln Create links between files. Links can be hard (two names for the same file) or soft (a shortcut of the first file).
317loadkeys Load keyboard translation tables.
318local Used to create function variables.
319locale Shows information about current or all locales.
320locate Used to find files by their name.
321lockfile Create semaphore file(s) which can be used to limit access to a file.
322logger Make entries in the system log.
323login Create a new session on the system.
324logname Shows the login name of the current user.
325logout Performs the logout operation by making changes to the utmp and wtmp files.
326logrotate Used for automatic rotation, compression, removal, and mailing of system log files.
327look Shows any lines in a file containing a given string in the beginning.
328losetup Set up and control loop devices.
329lpadmin Used to configure printer and class queues provided by CUPS (Common UNIX Printing System).
330lpc Line printer control program, it provides limited control over CUPS printer and class queues.
331lpinfo Shows the list of avaiable devices and drivers known to the CUPS server.
332lpmove Move on or more printing jobs to a new destination.
333lpq Shows current print queue status for a specified printer.
334lpr Used to submit files for printing.
335lprint Used to print a file.
336lprintd Used to abort a print job.
337lprintq List the print queue.
338lprm Cancel print jobs.
339lpstat Displays status information about current classes, jobs, and printers.
340ls Shows the list of files in the current directory.
341lsattr Shows file attributes on a Linux ext2 file system.
342lsblk Lists information about all available or the specified block devices.
343lsmod Show the status of modules in the Linux kernel.
344lsof List open files.
345lspci List all PCI devices.
346lsusb List USB devices.
347Linux Commands – M
348Command Description
349m4 Macro processor.
350mail Utility to compose, receive, send, forward, and reply to emails.
351mailq Shows to list all emails queued for delivery (sendmail queue).
352mailstats Shows current mail statistics.
353mailto Used to send mail with multimedia content in MIME format.
354make Utility to maintain groups of programs, recompile them if needed.
355makedbm Creates an NIS (Network Information Services) database map.
356makemap Creates database maps used by the keyed map lookups in sendmail.
357man Shows manual pages for Linux commands.
358manpath Determine search path for manual pages.
359mattrib Used to change MS-DOS file attribute flags.
360mbadblocks Checks MD-DOS filesystems for bad blocks.
361mcat Dump raw disk image.
362mcd Used to change MS-DOS directory.
363mcopy Used to copy MS-DOS files from or to Unix.
364md5sum Used to check MD5 checksum for a file.
365mdel, mdeltree Used to delete MS-DOS file. mdeltree recursively deletes MS-DOS directory and its contents.
366mdir Used to display an MS-DOS directory.
367mdu Used to display the amount of space occupied by an MS-DOS directory.
368merge Three-way file merge. Includes all changes from file2 and file3 to file1.
369mesg Allow/disallow osends to sedn write messages to your terminal.
370metamail For sending and showing rich text or multimedia email using MIME typing metadata.
371metasend An interface for sending non-text mail.
372mformat Used to add an MS-DOS filesystem to a low-level formatted floppy disk.
373mimencode Translate to/from MIME multimedia mail encoding formats.
374minfo Display parameters of an MS-DOS filesystem.
375mkdir Used to create directories.
376mkdosfs Used to create an MS-DOS filesystem under Linux.
377mke2fs Used create an ext2/ext3/ext4 filesystem.
378mkfifo Used to create named pipes (FIFOs) with the given names.
379mkfs Used to build a Linux filesystem on a hard disk partition.
380mkfs.ext3 Same as mke2fs, create an ext3 Linux filesystem.
381mkisofs Used to create an ISO9660/JOLIET/HFS hybrid filesystem.
382mklost+found Create a lost+found directory on a mounted ext2 filesystem.
383mkmanifest Makes a list of file names and their DOS 8.3 equivalent.
384mknod Create a FIFO, block (buffered) special file, character (unbuffered) special file with the specified name.
385mkraid Used to setup RAID device arrays.
386mkswap Set up a Linux swap area.
387mktemp Create a temporary file or directory.
388mlabel Make an MD-DOS volume label.
389mmd Make an MS-DOS subdirectory.
390mmount Mount an MS-DOS disk.
391mmove Move or rename an MS-DOS file or subdirectory.
392mmv Mass move and rename files.
393modinfo Show information about a Linux kernel module.
394modprobe Add or remove modules from the Linux kernel.
395more Display content of a file page-by-page.
396most Browse or page through a text file.
397mount Mount a filesystem.
398mountd NFS mount daemon.
399mpartition Partition an MS-DOS disk.
400mpg123 Command-line mp3 player.
401mpg321 Similar to mpg123.
402mrd Remove an MS-DOS subdirectory.
403mren Rename an existing MS-DOS file.
404mshowfat Show FTA clusters allocated to a file.
405mt Control magnetic tape drive operation.
406mtools Utilities to access MS-DOS disks.
407mtoolstest Tests and displays the mtools configuration files.
408mtr A network diagnostic tool.
409mtype Display contents of an MS-DOS file.
410mv Move/rename files or directories.
411mzip Change protection mode and eject disk on Zip/Jaz drive.
412Linux Commands – N
413Command Description
414named Internet domain name server.
415namei Follow a pathname until a terminal point is found.
416nameif Name network interfaces based on MAC addresses.
417nc Netcat utility. Arbitrary TCP and UDP connections and listens.
418netstat Show network information.
419newaliases Rebuilds mail alias database.
420newgrp Log-in to a new group.
421newusers Update/create new users in batch.
422nfsd Special filesystem for controlling Linux NFS server.
423nfsstat List NFS statistics.
424nice Run a program with modified scheduling priority.
425nl Show numbered line while displaying the contents of a file.
426nm List symbols from object files.
427nohup Run a command immune to hangups.
428notify-send A program to send desktop notifications.
429nslookup Used performs DNS queries. Read this article for more info.
430nsupdate Dynamic DNS update utility.
431Linux Commands – O
432Command Description
433objcopy Copy and translate object files.
434objdump Display information from object files.
435od Dump files in octal and other formats.
436op Operator access, allows system administrators to grant users access to certain root operations that require superuser privileges.
437open Open a file using its default application.
438openvt Start a program on a new virtual terminal (VT).
439Linux Commands – P
440Command Description
441passwd Change user password.
442paste Merge lines of files. Write to standard output, TAB-separated lines consisting of sqentially correspnding lines from each file.
443patch Apply a patchfile (containing differences listing by diff program) to an original file.
444pathchk Check if file names are valid or portable.
445perl Perl 5 language interpreter.
446pgrep List process IDs matching the specified criteria among all the running processes.
447pidof Find process ID of a running program.
448ping Send ICMP ECHO_REQUEST to network hosts.
449pinky Lightweight finger.
450pkill Send kill signal to processes based on name and other attributes.
451pmap Report memory map of a process.
452popd Removes directory on the head of the directory stack and takes you to the new directory on the head.
453portmap Converts RPC program numbers to IP port numbers.
454poweroff Shuts down the machine.
455pppd Point-to-point protocol daemon.
456pr Convert (column or paginate) text files for printing.
457praliases Prints the current system mail aliases.
458printcap Printer capability database.
459printenv Show values of all or specified environment variables.
460printf Show arguments formatted according to a specified format.
461ps Report a snapshot of the current processes.
462ptx Produce a permuted index of file contents.
463pushd Appends a given directory name to the head of the stack and then cd to the given directory.
464pv Monitor progress of data through a pipe.
465pwck Verify integrity of password files.
466pwconv Creates shadow from passwd and an optionally existing shadow.
467pwd Show current directory.
468python
469Linux Commands – Q
470Command Description
471quota Shows disk usage, and space limits for a user or group. Without arguments, only shows user quotas.
472quotacheck Used to scan a file system for disk usage.
473quotactl Make changes to disk quotas.
474quotaoff Enable enforcement of filesystem quotas.
475quotaon Disable enforcement of filesystem quotas.
476quotastats Shows the report of quota system statistics gathered from the kernel.
477Linux Commands – R
478Command Description
479raidstart Start/stop RAID devices.
480ram RAM disk device used to access the RAM disk in raw mode.
481ramsize Show usage information for the RAM disk.
482ranlib Generate index to the contents of an archive and store it in the archive.
483rar Create and manage RAR file in Linux.
484rarpd Respond to Reverse Address Resoultion Protocol (RARP) requests.
485rcp Remote copy command to copy files between remote computers.
486rdate Set system date and time by fetching information from a remote machine.
487rdev Set or query RAM disk size, image root device, or video mode.
488rdist Remote file distribution client, maintains identical file copies over multiple hosts.
489rdistd Start the rdist server.
490read Read from a file descriptor.
491readarray Read lines from a file into an array variable.
492readcd Read/write compact disks.
493readelf Shows information about ELF (Executable and Linkable fomrat) files.
494readlink Display value of a symbolic link or canonical file name.
495readonly Mark functions and variables as read-only.
496reboot Restart the machine.
497reject Accept/reject print jobs sent to a specified destination.
498remsync Synchronize remote files over email.
499rename Rename one or more files.
500renice Change priority of active processes.
501repquota Report disk usage and quotas for a specified filesystem.
502reset Reinitialize the terminal.
503resize2fs Used to resize ext2/ext3/ext4 file systems.
504restore Restore files from a backup created using dump.
505return Exit a shell function.
506rev Show contents of a file, reversing the order of characters in every line.
507rexec Remote execution client for exec server.
508rexecd Remote execution server.
509richtext View “richtext†on an ACSII terminal.
510rlogin Used to connect a local host system with a remote host.
511rlogind Acts as the server for rlogin. It facilitates remote login, and authentication based on privileged port numbers from trusted hosts.
512rm Removes specified files and directories (not by default).
513rmail Handle remote mail received via uucp.
514rmdir Used to remove empty directories.
515rmmod A program to remove modules from Linux kernel.
516rndc Name server control utility. Send command to a BIND DNS server over a TCP connection.
517rootflags Show/set flags for the kernel image.
518route Show/change IP routing table.
519routed A daemon, invoked at boot time, to manage internet routing tables.
520rpcgen An RPC protocol compiler. Parse a file written in the RPC language.
521rpcinfo Shows RPC information. Makes an RPC call to an RPC server and reports the findings.
522rpm A package manager for linux distributions. Originally developed for RedHat Linux.
523rsh Remote shell. Connects to a specified host and executes commands.
524rshd A daemon that acts as a server for rsh and rcp commands.
525rsync A versitile to for copying files remotely and locally.
526runlevel Shows previous and current SysV runlevel.
527rup Remote status display. Shows current system status for all or specified hosts on the local network.
528ruptime Shows uptime and login details of the machines on the local network.
529rusers Shows the list of the users logged-in to the host or on all machines on the local network.
530rusersd The rsuerd daemon acts as a server that responds to the queries from rsuers command.
531rwall Sends messages to all users on the local network.
532rwho Reports who is logged-in to the hosts on the local network.
533rwhod Acts as a server for rwho and ruptime commands.
534Linux Commands – S
535Command Description
536sane-find-scanner Find SCSI and USB scanner and determine their device files.
537scanadf Retrieve multiple images from a scanner equipped with an automatic document feeder (ADF).
538scanimage Read images from image aquistion devices (scanner or camera) and display on standard output in PNM (Portable aNyMap) format.
539scp Copy files between hosts on a network securely using SSH.
540screen A window manager that enables multiple pseudo-terminals with the help of ANSI/VT100 terminal emulation.
541script Used to make a typescript of everything displayed on the screen during a terminal session.
542sdiff Shows two files side-by-side and highlights the differences.
543sed Stream editor for filtering and transforming text (from a file or a pipe input).
544select Synchronous I/O multiplexing.
545sendmail It’s a mail router or an MTA (Mail Transfer Agent). sendmail support can send a mail to one or more recepients using necessary protocols.
546sensors Shows the current readings of all sensor chips.
547seq Displays an incremental sequence of numbers from first to last.
548set Used to manipulate shell variables and functions.
549setfdprm Sets floppy disk parameters as provided by the user.
550setkeycodes Load kernel scancode-to-keycode mapping table entries.
551setleds Show/change LED light settings of the keyboard.
552setmetamode Define keyboard meta key handling. Without arguments, shows current meta key mode.
553setquota Set disk quotas for users and groups.
554setsid Run a program in a new session.
555setterm Set terminal attributes.
556sftp Secure File Transfer program.
557sh Command interpreter (shell) utility.
558sha1sum Compute and check 160-bit SHA1 checksum to verify file integrity.
559shift Shift positional parameters.
560shopt Shell options.
561showkey Examines codes sent by the keyboard displays them in printable form.
562showmount Shows information about NFS server mount on the host.
563shred Overwrite a file to hide its content (optionally delete it), making it harder to recover it.
564shutdown Power-off the machine.
565size Lists section size and the total size of a specified file.
566skill Send a signal to processes.
567slabtop Show kernel slab cache information in real-time.
568slattach Attack a network interface to a serial line.
569sleep Suspend execution for a specified amount of time (in seconds).
570slocate Display matches by searching filename databases. Takes ownership and file permission into consideration.
571snice Reset priority for processes.
572sort Sort lines of text files.
573source Run commands from a specified file.
574split Split a file into pieces of fixed size.
575ss Display socket statistics, similar to netstat.
576ssh An SSH client for logging in to a remote machine. It provides encrypted communication between the hosts.
577ssh-add Adds private key identities to the authentication agent.
578ssh-agent It holds private keys used for public key authentication.
579ssh-keygen It generates, manages, converts authentication keys for ssh.
580ssh-keyscan Gather ssh public keys.
581sshd Server for the ssh program.
582stat Display file or filesystem status.
583statd A daemon that listens for reboot notifications from other hosts, and manages the list of hosts to be notified when the local system reboots.
584strace Trace system calls and signals.
585strfile Create a random access file for storing strings.
586strings Search a specified file and prints any printable strings with at least four characters and followed by an unprintable character.
587strip Discard symbols from object files.
588stty Change and print terminal line settings.
589su Change user ID or become superuser.
590sudo Execute a command as superuser.
591sum Checksum and count the block in a file.
592suspend Suspend the execution of the current shell.
593swapoff Disable devices for paging and swapping.
594swapon Enable devices for paging and swapping.
595symlink Create a symbolic link to a file.
596sync Synchronize cached writes to persistent storage.
597sysctl Configure kernel parameters at runtime.
598sysklogd Linux system logging utilities. Provides syslogd and klogd functionalities.
599syslogd Read and log system messages to the system console and log files.
600Linux Commands – T
601Command Description
602tac Concatenate and print files in reverse order. Opposite of cat command.
603tail Show the last 10 lines of each specified file(s).
604tailf Follow the growth of a log file. (Deprecated command)
605talk A two-way screen-oriented communication utility that allows two user to exchange messages simulateneously.
606talkd A remote user communication server for talk.
607tar GNU version of the tar archiving utility. Used to store and extract multiple files from a single archive.
608taskset Set/retrieve a process’s CPU affinity.
609tcpd Access control utility for internet services.
610tcpdump Dump traffic on network. Displays a description of the contents of packets on a network interface that match the boolean expression.
611tcpslice Extract pieces of tcpdump files or merge them.
612tee Read from standard input and write to standard output and files.
613telinit Change SysV runlevel.
614telnet Telnet protocol user interface. Used to interact with another host using telnet.
615telnetd A server for the telnet protocol.
616test Check file type and compare values.
617tftp User interface to the internet TFTP (Trivial File Transfer Protocol).
618tftpd TFTP server.
619time Run programs and summarize system resource usage.
620timeout Execute a command with a time limit.
621times Shows accumulated user and system times for the shell and it’s child processes.
622tload Shows a graph of the current system load average to the specified tty.
623tmpwatch Recursively remove files and directories which haven’t been accessed for the specified period of time.
624top Displays real-time view of processes running on the system.
625touch Change file access and modification times.
626tput Modify terminal-dependent capabilities, color, etc.
627tr Translate, squeeze, or delete characters from standard input and display on standard output.
628tracepath Traces path to a network host discovering MTU (Maximum Transmission Unit) along this path.
629traceroute Traces the route taken by the packets to reach the network host.
630trap Trap function responds to hardware signals. It defines and creates handlers to run when the shell receives signals.
631troff The troff processor of the groff text formatting system.
632TRUE Exit with a status code indicating success.
633tset Initialize terminal.
634tsort Perform topological sort.
635tty Display the filename of the terminal connected to standard input.
636tune2fs Adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems.
637tunelp Set various parameters for the line printer devices.
638type Write a description for a command type.
639Linux Commands – U
640Command Description
641ul Underline text.
642ulimit Get and set user limits for the calling process.
643umask Set file mode creation mask.
644umount Unmount specified file systems.
645unalias Remove alias definitions for specified alias names.
646uname Show system information.
647uncompress Uncompress the files compressed with the compress command.
648unexpand Convert spaces to tabs for a specified file.
649unicode_start Put keyboard and console in Unicode mode.
650unicode_stop Revert keyboard and console from Unicode mode.
651uniq Report or omit repeating lines.
652units Convert units from one scalar to another.
653unrar Extract files from a RAR archive.
654unset Remove variable or function names.
655unshar Unpack shell archive scripts.
656until Execute command until a given condition is true.
657uptime Tell how long the system has been running.
658useradd Create a new user or update default user information.
659userdel Delete a user account and related files.
660usermod Modify a user account.
661users Show the list of active users on the machine.
662usleep Suspend execution for microsecond intervals.
663uudecode Decode a binary file.
664uuencode Encode a binary file.
665uuidgen Created a new UUID (Universally Unique Identifier) table.
666Linux Commands – V
667Command Description
668vdir Same as ls -l -b. Verbosely list directory contents.
669vi A text editor utility.
670vidmode Set the video mode for a kernel image. Displays current mode value without arguments. Alternative: rdev -v
671vim Vi Improved, a text-based editor which is a successor to vi.
672vmstat Shows information about processes, memory, paging, block IO, traps, disks, and CPU activity.
673volname Returns volume name for a device formatted with an ISO-9660 filesystem. For example, CD-ROM.
674Linux Commands – W
675Command Description
676w Show who is logged-on and what they’re doing.
677wait Waits for a specified process ID(s) to terminate and returns the termination status.
678wall Display a message on the terminals all the users who are currently logged-in.
679warnquota Send mail to the users who’ve exceeded their disk quota soft limit.
680watch Runs commands repeatedly until interr
681zdump Displays time for the timezone mentioned.upted and shows their output and errors.
682wc Print newline, word, and byte count for each of the specified files.
683wget A non-interactive file download utility.
684whatis Display one line manual page descriptions.
685whereis Locate the binary, source, and man page files for a command.
686which For a given command, lists the pathnames for the files which would be executed when the command runs.
687while Conditionally execute commands (while loop).
688who Shows who is logged on.
689whoami Displays the username tied to the current effective user ID.
690whois Looks for an object in a WHOIS database
691write Display a message on other user’s terminal.
692Linux Commands – X
693Command Description
694xargs Runs a command using initial arguments a
695zdump Displays time for the timezone mentioned.nd then reads remaining arguments from standard input.
696xdg-open Used to open a file or URL in an application preferred by the user.
697xinetd Extended internet services daemon. Works similar to inetd.
698xz Compress/ Decompress .xz and .lzma files.
699Linux Commands – Y
700Command Description
701yacc Yet Another Compiler Compiler, a GNU Project parser generator.
702yes Repeatedly output a line with a specified string(s) until killed.
703ypbind A daemon that helps client processes to connect to an NIS server.
704ypcat Shows the NIS map (or database) for the specified MapName parameter.
705ypinit Sets up NIS maps on an NIS server.
706ypmatch Shows values for specified keys from an NIS map.
707yppasswd Change NIS login password.
708yppasswdd Acts as a server for the yppasswd command. Receives and executes requests.
709yppoll Shows the ID number or version of NIS map currently used on the NIS server.
710yppush Forces slave NIS servers to copy updated NIS maps.
711ypserv A daemon activated at system startup. It looks for information in local NIS maps.
712ypset Point a client (running ypbind) to a specifc server (running ypserv).
713yptest Calls various functions to check the configuration of NIS services.
714ypwhich Shows the hostname for NIS server or master server for a given map.
715ypxfr Transfers NIS server map from server to a local host.
716Linux Commands – Z
717Command Description
718zcat Used to compress/uncompress files. Similar to gzip
719zcmp Compare compressed files.
720zdiff Compare compressed files line by line.
721zdump Displays time for the timezone mentioned.
722zforce Adds .gz extension to all gzipped files.
723zgrep Performs grep on compressed files.
724zic Creates time conversion information files using the specified input files.
725zip A file compression and packaging utility.
726zless Displays information of a compressed file (using less command) on the terminal one screen at a time.
727zmore Displays output of a compressed file (using more command) on the terminal one page at a time.
728znew Recompress .z files to .gz. files.