Linux Terminal for beginners.
Must know these commands to start your Linux terminal journey.
Introduction:
The terminal is an important part of any operating system if you're a literal computer user then you don’t need to know about the terminal. If you are a programmer, typist, or even anything which needs long hours of computer work then you have to grasp the terminal.
The Linux command line is a text interface to your computer. Often referred to as the shell, terminal, console, prompt, or various other names, it can give the appearance of being complex and confusing to use. Yet the ability to copy and paste commands from a website, combined with the power and flexibility the command line offers
-from linux official website
1. pwd Command
pwd command displays the name of the current/working directory as below.
$ pwdls Command
ls command is used to list the contents of a directory. It works more or less like dir command.
The -l option enables a long listing format like this.
$ ls -l file11. List Files using ls with no option
ls with no option list files and directories in a bare format where we won’t be able to view details like file types, size, modified date and time, permission and links, etc.
# ls0001.pcap Desktop Downloads index.html install.log.syslog Pictures Templates
anaconda-ks.cfg Documents fbcmd_update.php install.log Music Public Videos
2 List Files With option –l
Here, ls -l (-l is a character, not one) shows file or directory, size, modified date and time, file or folder name, and owner of the file and its permission.
# ls -ltotal 176
-rw-r--r--. 1 root root 683 Aug 19 09:59 0001.pcap
-rw-------. 1 root root 1586 Jul 31 02:17 anaconda-ks.cfg
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Desktop
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Documents
drwxr-xr-x. 4 root root 4096 Aug 16 02:55 Downloads
-rw-r--r--. 1 root root 21262 Aug 12 12:42 fbcmd_update.php
-rw-r--r--. 1 root root 46701 Jul 31 09:58 index.html
-rw-r--r--. 1 root root 48867 Jul 31 02:17 install.log
-rw-r--r--. 1 root root 11439 Jul 31 02:13 install.log.syslog
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Music
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Pictures
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Public
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Templates
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Videos
3. View Hidden Files
List all files including hidden files starting with ‘.‘.
# ls -a. .bashrc Documents .gconfd install.log .nautilus .pulse-cookie
.. .cache Downloads .gnome2 install.log.syslog .netstat.swp .recently-used.xbel
0001.pcap .config .elinks .gnome2_private .kde .opera .spice-vdagent
anaconda-ks.cfg .cshrc .esd_auth .gtk-bookmarks .libreoffice Pictures .tcshrc
.bash_history .dbus .fbcmd .gvfs .local .pki Templates
.bash_logout Desktop fbcmd_update.php .ICEauthority .mozilla Public Videos
.bash_profile .digrc .gconf index.html Music .pulse .wireshark
4. List Files with Human Readable Format with option -lh
With a combination of -lh option, shows sizes in human-readable format.
# ls -lhtotal 176K
-rw-r--r--. 1 root root 683 Aug 19 09:59 0001.pcap
-rw-------. 1 root root 1.6K Jul 31 02:17 anaconda-ks.cfg
drwxr-xr-x. 2 root root 4.0K Jul 31 02:48 Desktop
drwxr-xr-x. 2 root root 4.0K Jul 31 02:48 Documents
drwxr-xr-x. 4 root root 4.0K Aug 16 02:55 Downloads
-rw-r--r--. 1 root root 21K Aug 12 12:42 fbcmd_update.php
-rw-r--r--. 1 root root 46K Jul 31 09:58 index.html
-rw-r--r--. 1 root root 48K Jul 31 02:17 install.log
-rw-r--r--. 1 root root 12K Jul 31 02:13 install.log.syslog
drwxr-xr-x. 2 root root 4.0K Jul 31 02:48 Music
drwxr-xr-x. 2 root root 4.0K Jul 31 02:48 Pictures
drwxr-xr-x. 2 root root 4.0K Jul 31 02:48 Public
drwxr-xr-x. 2 root root 4.0K Jul 31 02:48 Templates
drwxr-xr-x. 2 root root 4.0K Jul 31 02:48 Videos
5. List Files and Directories with ‘/’ Character at the end
Using -F option with ls command will add the ‘/’ Character at the end of each directory.
# ls -F0001.pcap Desktop/ Downloads/ index.html install.log.syslog Pictures/ Templates/
anaconda-ks.cfg Documents/ fbcmd_update.php install.log Music/ Public/ Videos/
6. List Files in Reverse Order
The following command with ls -r option displays files and directories in reverse order.
# ls -rVideos Public Music install.log fbcmd_update.php Documents anaconda-ks.cfg
Templates Pictures install.log.syslog index.html Downloads Desktop 0001.pcap
7. Recursively list Sub-Directories
ls -R option will list very long listing directory trees. See an example of the output of the command.
# ls -Rtotal 1384
-rw-------. 1 root root 33408 Aug 8 17:25 anaconda.log
-rw-------. 1 root root 30508 Aug 8 17:25 anaconda.program.log./httpd:
total 132
-rw-r--r-- 1 root root 0 Aug 19 03:14 access_log
-rw-r--r--. 1 root root 61916 Aug 10 17:55 access_log-20120812./lighttpd:
total 68
-rw-r--r-- 1 lighttpd lighttpd 7858 Aug 21 15:26 access.log
-rw-r--r--. 1 lighttpd lighttpd 37531 Aug 17 18:21 access.log-20120819./nginx:
total 12
-rw-r--r--. 1 root root 0 Aug 12 03:17 access.log
-rw-r--r--. 1 root root 390 Aug 12 03:17 access.log-20120812.gz
8. Reverse Output Order
With a combination of -ltr will show the latest modification file or directory date as the last.
# ls -ltrtotal 176
-rw-r--r--. 1 root root 11439 Jul 31 02:13 install.log.syslog
-rw-r--r--. 1 root root 48867 Jul 31 02:17 install.log
-rw-------. 1 root root 1586 Jul 31 02:17 anaconda-ks.cfg
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Desktop
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Videos
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Templates
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Public
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Pictures
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Music
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Documents
-rw-r--r--. 1 root root 46701 Jul 31 09:58 index.html
-rw-r--r--. 1 root root 21262 Aug 12 12:42 fbcmd_update.php
drwxr-xr-x. 4 root root 4096 Aug 16 02:55 Downloads
-rw-r--r--. 1 root root 683 Aug 19 09:59 0001.pcap
9. Sort Files by File Size
With a combination of -lS displays file size in order, will display big in size first.
# ls -lStotal 176
-rw-r--r--. 1 root root 48867 Jul 31 02:17 install.log
-rw-r--r--. 1 root root 46701 Jul 31 09:58 index.html
-rw-r--r--. 1 root root 21262 Aug 12 12:42 fbcmd_update.php
-rw-r--r--. 1 root root 11439 Jul 31 02:13 install.log.syslog
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Desktop
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Documents
drwxr-xr-x. 4 root root 4096 Aug 16 02:55 Downloads
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Music
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Pictures
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Public
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Templates
drwxr-xr-x. 2 root root 4096 Jul 31 02:48 Videos
-rw-------. 1 root root 1586 Jul 31 02:17 anaconda-ks.cfg
-rw-r--r--. 1 root root 683 Aug 19 09:59 0001.pcap
10. Display Inode number of File or Directory
We can see some numbers printed before file/directory name. With -i options list file/directory with an inode number.
# ls -i20112 0001.pcap 23610 Documents 23793 index.html 23611 Music 23597 Templates
23564 anaconda-ks.cfg 23595 Downloads 22 install.log 23612 Pictures 23613 Videos
23594 Desktop 23585 fbcmd_update.php 35 install.log.syslog 23601 Public
11. Shows version of ls command
Check the version of ls command.
# ls --versionls (GNU coreutils) 8.4
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Richard M. Stallman and David MacKenzie.
12. Show Help Page
The list help page of ls command with their option.
# ls --helpUsage: ls [OPTION]... [FILE]...
13. List Directory Information
With ls -l command list files under directory /tmp. Wherein with -ld parameters displays information of /tmp directory.
# ls -l /tmp
total 408
drwx------. 2 narad narad 4096 Aug 2 02:00 CRX_75DAF8CB7768
-r--------. 1 root root 384683 Aug 4 12:28 htop-1.0.1.tar.gz
drwx------. 2 root root 4096 Aug 4 11:20 keyring-6Mfjnk
drwx------. 2 root root 4096 Aug 16 01:33 keyring-pioZJr
drwx------. 2 gdm gdm 4096 Aug 21 11:26 orbit-gdm
drwx------. 2 root root 4096 Aug 19 08:41 pulse-gl6o4ZdxQVrX
drwx------. 2 narad narad 4096 Aug 4 08:16 pulse-UDH76ExwUVoU
drwx------. 2 gdm gdm 4096 Aug 21 11:26 pulse-wJtcweUCtvhn
-rw-------. 1 root root 300 Aug 16 03:34 yum_save_tx-2012-08-16-03-34LJTAa1.yumtx# ls -ld /tmp/drwxrwxrwt. 13 root root 4096 Aug 21 12:48 /tmp/
14. Display UID and GID of Files
To display UID and GID of files and directories. use option -n with ls command.
# ls -ntotal 36
drwxr-xr-x. 2 500 500 4096 Aug 2 01:52 Downloads
drwxr-xr-x. 2 500 500 4096 Aug 2 01:52 Music
drwxr-xr-x. 2 500 500 4096 Aug 2 01:52 Pictures
-rw-rw-r--. 1 500 500 12 Aug 21 13:06 tmp.txt
drwxr-xr-x. 2 500 500 4096 Aug 2 01:52 Videos
15. ls command and its Aliases
We have made an alias for ls command when we execute ls command it’ll take -l option by default and display a long listing as mentioned earlier.
# alias ls="ls -l"Note: We can see a number of aliases available in your system with the below alias command and the same can be un-alias as shown below example.
# aliasalias cp='cp -i'
alias l.='ls -d .* --color=auto'
alias ll='ls -l --color=auto'
alias ls='ls --color=auto'
alias mv='mv -i'
alias rm='rm -i'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'
To remove an alias previously defined, just use the un-alias command.
# unalias ls
