While the GUI may have an appeal of its own, it simply doesn’t have the pace of a lightning fast command line on Linux. In the command line, you can rattle off several commands in a matter of seconds. Likewise, your capabilities are only limited by the number of linux commands you know rather than the display on your screen.
If you have a wide vocabulary then the sky’s the limit. If not, then you’re more restricted in what you can do. However, if you’re part of the latter group don’t fear, we’re here to assist you with the only Linux commands you’ll ever need. This guide has been designed specifically for network administrators to take you from passable command knowledge to outright fluency.
Overview from A-Z:
A: acpi, alias, apropos, apt-get, arch, Aspell, autoupdate 8. AWK
B: bash, bg, bzip2
C: cat, cd, chmod, chown, cmp, comm, cp, cpio, CRON
D: date, declare, dirs, df
E: echo, enable, env, eval, exec, exit, expect, export
F: fc-list, find, for, free, fsck
G: grep, grpck, gunzip, gzip, groffer
H: hash, head, history, hostid, hwclock
I: ifconfig, ifup, ifdown
J: jobs, join
K: kbdrate, kill, killall
L: less, locate, lft, lftp, ln, Is
M: man, mc, mkdir, mmv, mtr
N: neat, netconfig/netcfg, netstat, notify-send, nslookup
O: objcopy, od, openvt
P: passwd, ping, poweroff, ps, pwd
Q: quota, quotacheck, quotactl
R: read, RPM, rsync
S: screen, sdiff, sed, shutdown, Snort, sort, sudo, SSH
T: tar, tcpdump, telnet, TOP, Tr, traceroute
U: uname, uniq
V: vi, vmstat
W: wc, Wget, whoami
X: xargs, xdg-open
Y: yppasswd, yppoll, yptest
Z: zcat, zcmp, zdiff, zip
A
| No. | Command Name | Description |
|---|
| 1 | acpi | Shows information about the Advanced Configuration and Power Interface. |
| 2 | alias | Runs a command (or series of commands) with a shorter name than the full command name). |
| 3 | apropos | Displays a list of all topics from the man pages related to your query. |
| 4 | apt-get | Used to update a Debian machine automatically and install a package or program. |
| 5 | Arch | Displays print machine hardware name.
|
| 6 | Aspell | GNU Aspell is an open source spell checker utility. |
| 7 | autoupdate | Updates a configure.in file to a new autoconf. |
| 8 | AWK | Find and replace text in a file. |
B
| No. | Command | Description |
|---|
| 9 | bash | GNU Bourne-Again Shell. |
| 10 | bg | Sends processes to the background. |
| 11 | bzip2 | An open source program that is used to compress or decompress files rapidly. |
C
| No. | Command | Description |
|---|
| 12 | cat | Used to read, modify, or concentrate text files. |
| 13 | cd | Changes the current directory. |
| 14 | chmod | Changes the permissions or access mode of a file(s). Only a privileged user or file owner can change the access mode. |
| 15 | chown | Changes the ownership of a file or group of files. Can change ownership for objects within an entire directory tree. |
| 16 | cmp | Compares two files. If the files are the same nothing happens but if they’re different then cmp reports to byte and line number. |
| 17 | comm | Compares two files line by line. |
| 18 | cp | Copies files and directories. |
| 19 | cpio | Copies files in or out of a cpio or tar archive (a tar archive is a file with other files inside it). Tar archives also include information including; owner, file name, timestamps and access permissions. |
| 20 | CRON | Daemon used to execute programs at a specific time. You need to create a text file that dictates what file will be executed and the time to be executed. CRON then loads the text file. |
D
| No. | Command | Description |
|---|
| 21 | date | Used to set the date and time of a system. |
| 22 | declare | Used to declare variables and provide them with attributes. |
| 23 | dirs | Shows a list of remembered directories. |
| 24 | df | Shows how much disk usage there is on your system. |
E
| No. | Command | Description |
|---|
| 25 | echo | Used with shell scripts to enable a user to repeat a string variable to a standard output. |
| 26 | enable | Used to start or stop printers and classes. |
| 27 | env | Displays current environment variables. |
| 28 | eval | Used to evaluate several arguments at once and concatenates them into one command. |
| 29 | exec | Replaces parent process with the entered command. |
| 30 | exit | Exits the terminal/terminates a script. |
| 31 | expect | Talks to other programs and waits for a response. |
| 32 | export | Converts one file into a different format. |
F
| No. | Command | Description |
|---|
| 33 | fc-list | Shows a list of available fonts. |
| 34 | find | Searches the directory tree for groups that meet certain conditions. These conditions include, name, user, type, size, exec, and mtime. |
| 35 | for, while | Used to execute or loop items indefinitely (so long as certain criteria is met). |
| 36 | free | Shows you how much free space there is in your memory. You can also view used memory too. |
| 37 | fsck | Used to check and repair a file system. |
G
| No. | Command | Description |
|---|
| 38 | grep | Searches files for a specific pattern or character string to replace with another. This command is generally used for searching for files. |
| 39 | grpck | Used to verify the integrity of a group’s information. |
| 40 | gunzip | Opens a utility used to compress and expand files. |
| 41 | gzip | GNU open source program used for file compression. |
| 42 | groffer | Display groff files and man pages. |
H
| No. | Command | Description |
|---|
| 43 | hash | Shows the command path locations. |
| 44 | head | Shows first 10 lines of specified files. |
| 45 | history | Shows the systems command history. |
| 46 | hostid | Shows hosts ID in hexadecimal format. |
| 47 | hwclock | View/configure the hardware clock. |
I
| No. | Command | Description |
|---|
| 48 | ifconfig | This command is used to configure resident kernel network interfaces. Most of the time it is used when booting up but it can also be used for debugging as well. |
| 49 | ifup | Used to configure a network interface and enable a network connection. |
| 50 | ifdown | Used to shut down a network interface and disable a network connection. |
J
| No. | Command | Description |
|---|
| 51 | jobs | Shows a list of active jobs. Also shows job status. |
| 52 | join | Joins lines of two files on a common field. |
K
| No. | Command | Description |
|---|
| 53 | kbdrate | Resets the keyboard repeat rate/delay time. |
| 54 | kill | Sends a kill signal to a one or more processes. |
| 55 | killall | Sends a kill signal to all processes running the specified command. |
L
| No. | Command | Description |
|---|
| 56 | less | Displays contents of a file one page at a time. |
| 57 | locate, slocate
| Locate is used to read a database(s) and outputs files that match certain patterns. Similarly slocate (secure locate) is used to index files, search for files, and store file permissions securely. |
| 58 | lft | Identifies connection routes and provides additional information useful for debugging connections. |
| 59 | lftp | An FTP utility. |
| 60 | In | Creates a new name for a file via a hard link. In practice this allows multiple users to share a single file. |
| 61 | Is | Lists files and directories within the current working directory. |
M
| No. | Command | Description |
|---|
| 62 | man | Displays the user manual pages on Linux commands. |
| 63 | mc | A text-based file manager or visual shell for Unix systems. |
| 64 | mkdir | Creates directories. |
| 65 | mmv | Moves and renames files en masse. |
| 66 | mtr | Network diagnostic tool. |
N
| No. | Command | Description |
|---|
| 67 | neat | A GNOME GUI admin tool which allows users to dictate what information is needed to set up a network card. |
| 68 | netconfig/netcfg
| Configures a network and enables network products. |
| 69 | netstat | Shows information about active protocols in TCP/IP network connections. |
| 70 | notify-send
| A program used to send desktop notifications. |
| 71 | nslookup | Enter a host name and find the accompanying IP address. You can also reverse this. |
O
| No. | Command | Description |
|---|
| 72 | objcopy | Copies and translates object files. |
| 73 | od | Dumps binary files in octal, hex, or binary to standard output. |
| 74 | openvt | Starts a program through a virtual terminal. |
P
| No. | Command | Description |
|---|
| 75 | passwd | Updates the user’s current password. |
| 76 | ping | Enables the user to check that an IP address exists. Can also determine response times. |
| 77 | poweroff | Shuts the machine down. |
| 78 | ps | Reports status of all current processes within a system. |
| 79 | pwd | Shows the name of the current working directory. |
Q
| No. | Command | Description |
|---|
| 80 | quota | Shows disk usage for a user or group. |
| 81 | quotacheck | Scans a file system for disk usage.
|
| 82 | quotactl | Change disk quotas.
|
R
| No. | Command | Description |
|---|
| 83 | read | Takes lines of text from a standard input and assigns values to each file. |
| 84 | RPM | RPM or Red Hat Package Manager is a command line program that allows you to install, manage, or uninstall software packages with Linux. |
| 85 | rsync | Syncs data from one file (or disk) to another. Good choice for data backups. |
S
| No. | Command | Description |
|---|
| 86 | screen | A window manager which allows the user to run multiple terminal applications or windows through one terminal window. |
| 87 | sdiff | Looks for differences between two files. Shows you lines that are dissimilar before merging them. |
| 88 | sed | This is a stream editor that is used to filter text. Used to filter, extract and replace parts of files. |
| 89 | shutdown | Shuts down the computer. If you combine with -h it will stop after shutdown or you can use -r to reboot automatically after shutdown. |
| 90 | Snort | A network intrusion detection system and packet sniffer based in libpcap. Used to monitor network traffic. |
| 91 | sort | Sorts text alphabetically or numerically. |
| 92 | sudo | Gives the user permissions to run some or all commands. |
| 93 | SSH | Command interface used for gaining access to remote computer securely. |
T
No.
| Command | Description |
|---|
| 94 | tar | You can create archives from a number of specified files. |
| 95 | tcpdump | Network packet analysis tool. |
| 96 | telnet | User interface for the Telnet protocol. |
| 97 | TOP | Allows you to monitor system processes with distributed information processing. Sorts tasks by CPU usage, memory usage and runtime. |
| 98 | tr | Translates or deletes characters from a text stream. Only accepts standard input. |
| 99 | traceroute | Identifies and records a route over the internet between two computers. Good for troubleshooting and determining network issues. |
U
| No. | Command | Description |
|---|
| 100 | uname | Displays the name of the current operating information. Can also print information. |
| 101 | uniq | Compares lines adjacent lines within a file and removes duplicate lines. |
V
| No. | Command | Description |
|---|
| 102 | vi | Vi is a well known text editor that allows users to control their system via the keyboard. |
| 103 | vmstat | Gives the user a snapshot of everything with information on things like memory, processes, paging and CPU activity. |
W
| No. | Command | Description |
|---|
| 104 | wc | Counts the number of words, lines, and characters in text files. |
| 105 | Wget | Network utility used to pull files from the web with support for http, https, and ftp. Works in the background while a user is logged off. |
| 106 | whoami | Products the user/login name linked to the current user ID. |
X
| No. | Command | Description |
|---|
| 107 | xargs | Uses standard input to read, build, and execute arguments. |
| 108 | xdg-open
| Opens a file or UTL in the user’s preferred application. |
Y
| No. | Command | Description |
|---|
| 109 | yppasswd | Changes NIS login password.
|
| 110 | yppoll | Shows the ID number/version of NIS map on the NIS server.
|
| 111 | yptest | Uses NIS functions to check if NIS configuration is correct.
|
Z
| No. | Command | Description |
|---|
| 112 | zcat | Compresses/uncompress files (similar to gzip).
|
| 113 | zcmp | Compares compressed files.
|
| 114 | zdiff | Compares compressed files line by line.
|
| 115 | zip | Compression and file packing utility.
|
Conclusion
When it comes to Linux commands, there is no telling how many commands there actually are. The commands available on a Linux system depend on the operating system you’re on. That being said the list is extensive and the commands we’ve covered in this article are just the tip of the iceberg. However few commands will be as integral to your day-to-day usage as the commands outlined above.
These commands will give you a lot of mileage so that you can supplement in niche commands as you learn them. Obviously, the catch is you’re going to need to learn them first! While much of this will rely on you simply using the commands over and over again you can also use this guide as a cheat-sheet. However, if you want to make things easier there is a command you can use to help you locate other commands. This is called the Apropos command. We’ve listed this above but we will repeat below for convenience:
apropos “list directory”
Depending on the command you searched for, this will bring up a list of relevant commands. The example above would display commands such as dir, ls, ntfsls, and vdir. Ultimately the more time you spend using these commands the better you’ll retain them and the more you’ll get out of your distribution.
