The most important Linux commands you need daily

Use this guide to most important Linux commands, Utilities, and tools for beginners, enterprise administrators, and managers.

Directory Operations:

Command Description pwd Show current directory cd dir Change to directory dir mkdir dir Create a new directory dir rmdir dir Delete directory dir ls dir List Contents directory dir

Example:

vijayan@vijayan-VPCCA35FA:~$ pwd /home/vijayan vijayan@vijayan-VPCCA35FA:~$ cd Downloads/ vijayan@vijayan-VPCCA35FA:~/Downloads$ mkdir techpulsetoday vijayan@vijayan-VPCCA35FA:~/Downloads$ ls techpulsetoday vijayan@vijayan-VPCCA35FA:~/Downloads$ rmdir techpulsetoday/

Special Directories:

Command Description . Current Directory .. Up a Directory ~ Home Directory / Root Directory - Previous Directory

Example:

vijayan@vijayan-VPCCA35FA:~$ pwd /home/vijayan vijayan@vijayan-VPCCA35FA:~$ cd . vijayan@vijayan-VPCCA35FA:~$ pwd /home/vijayan vijayan@vijayan-VPCCA35FA:~$ cd .. vijayan@vijayan-VPCCA35FA:/home$ pwd /home vijayan@vijayan-VPCCA35FA:/home$ cd ~ vijayan@vijayan-VPCCA35FA:~$ pwd /home/vijayan vijayan@vijayan-VPCCA35FA:~$ cd / vijayan@vijayan-VPCCA35FA:/$ pwd / vijayan@vijayan-VPCCA35FA:/$ cd - /home/vijayan vijayan@vijayan-VPCCA35FA:~$

ls Options:

Syntax:

ls [options] [file|dir]

Command Description -a All inc. hidden file -l Long Format -i List file's inode index number -t Sort by time & date -d List directories with ' */' [eg1. ls -d */ ][eg2. ls -d $PWD/* ] -s List file size -S Sort by time -r Reverse order -R Recursive -X Sort by extension name

Example:

vijayan@vijayan-VPCCA35FA:~/Music/ringtone$ ls -lash total 5.3M 4.0K drwxrwxr-x 2 vijayan vijayan 4.0K Jan 3 01:51 . 4.0K drwxr-xr-x 3 vijayan vijayan 4.0K Dec 31 22:53 .. 648K -rw-rw-r-- 1 vijayan vijayan 643K Dec 31 22:53 Aval Azhakai.mp3 564K -rw-rw-r-- 1 vijayan vijayan 557K Dec 31 22:54 Azhagiya Theeye.mp3 480K -rw-rw-r-- 1 vijayan vijayan 475K Dec 31 22:54 Azhagiya Theeye Whistle.mp3 680K -rw-rw-r-- 1 vijayan vijayan 675K Dec 31 22:55 Iru Vizhi unathu.mp3 624K -rw-rw-r-- 1 vijayan vijayan 617K Dec 31 22:55 Nenjai Poopoal.mp3 584K -rw-rw-r-- 1 vijayan vijayan 580K Dec 31 22:55 Pooppol Pooppol.mp3 540K -rw-rw-r-- 1 vijayan vijayan 536K Dec 31 22:55 Vaseegara Theme.mp3 620K -rw-rw-r-- 1 vijayan vijayan 613K Dec 31 22:55 Venmathi love fail.mp3 596K -rw-rw-r-- 1 vijayan vijayan 590K Dec 31 22:56 Verenna Verenna Male.mp3

File Operations:

Command Descriptions touch file Create a new file cp file1 file2 Copy file1 to file2 mv file1 file2 Move file1 to file2 rm file Delete a file cat file Display content of a file cat file1 file2 Cancatenate files less file Display file (paginated), q to quit head file Show first 10 lines tail file Show last 10 lines [-n N →N lines; -f → Continuos update]

File Searching:

Command Descriptions grep pattern file Searching for a line with a pattern in a file grep -v Inverted search grep -r Recursive search grep -e pattern -e pattern Multiple patterns locate file Quick search for a file which cmd Find locations of binary find dir -name pattern Find a file with a pattern in dir

Example:

grep -rnw '/var/www/html/' -e "techpulsetoday"

Standard IO Streams:

Command Descriptions stdin Input typed on the command line stdout Output on the screen stderr Errors output on the screen echo string Write a string to stdout

Example:

echo 'password' | sudo -S cp wp-config.php bkp-wp-config.php

Redirection:

Command Descriptions cmd > file Output of cmd to file cmd < file file used as input to cmd cmd >> file Append output to file cmd 2> file Write errors to file cmd &> file Errors and stdout to file

Pipe Multiple Commands

Command Descriptions cmd1 | cmd2 Stdout of cmd1 is used as input to cmd2 cmd1 | &cmd2 Stderr of cmd1 is used as input to cmd2 cmdpart1 \ cmdpart2 Continue command on next line cmd1; cmd2 Execute cmd1 then cmd2

Processes:

Command Descriptions ps Show processes of user ps -e Show all processes ps -fA Show all processes in detail top Show all processes in real-time cmd & Run command in the background Ctrl-c Stop (kill) currently active process Ctrl-z Suspend currently active process bg Place suspended process in a background fg Bring background process to foreground kill pid Kill process with process id PID Kill -9 pid Kill process PID (ungraceful)

Bash Shortcuts:

Command Descriptions Ctrl-k Cut line of text Ctrl-y Past line of text Ctrl-e Go to end of line Ctrl-a Go to start of line TAB Autocomplete command/file TAB-TAB Show list of possible autocompletes up arrow Scroll previous commands down arrow Scroll previous commands histrory List recent commands !! Repeat the last command !N Execute command N from history !abc:p Print the last command starting with abc !abc Execute the last command starting with abc

Text file operation:

Command Descriptions wc Line, word and character count sort file Sort file, line by line uniq file Display only unique lines of a file sed ‘s/abc/def/g’ file Replace all occurrence of abc with def, out to stdout cut -d “ “ -f N file Display field N of space delimited file cut -d “,” -f M-N file Display field M-N of a comma delimited file

Tar Command:

Command Descriptions -c Creates a new .tar archive file. -x To untar or extract a tar file -v Verbosely show the .tar file progress. -f File name type of the archive file. -z compressed gzip archive file -r To add files or directories to existing tar archive file -j To create a highly compressed tar file -C untar in a different directory -t viewing content of archive file -W Verify an archive file

Example:

How to create a tar.gz file

To create a tar.gz archive from a given folder you can use the following command

tar -zcvf tar-archive-name.tar.gz source-folder-name

How to extract a tar.gz file

To extract a tar.gz compressed archive you can use the following command

tar -zxvf tar-archive-name.tar.gz

How to extract specific file(s) from tar.gz

tar -zxvf <tar filename> <file you want to extract>

Proper file Permissions for WordPress

sudo chown www-data:www-data -R * sudo find . -type d -exec chmod 755 {} \; sudo find . -type f -exec chmod 644 {} \; sudo chmod 444 wp-config.php sudo chmod 444 .htaccess

Three-digit permissions specified in octal

stat -c "%a %n" *

How to find recently modified files

see all files that were modified during the last 2 days

find . -mtime -2 -ls

How can I monitor the progress of an import of a large .sql file?

If you’re just importing from a dump file from the CLI on *nix, e.g.

mysql -uxxx -pxxx dbname < /sqlfile.sql

then first install pipe viewer on your OS then try something like this:

pv sqlfile.sql | mysql -uxxx -pxxxx dbname

How to convert ppk file from pem file?

Make sure puttygen installed on your computer. If it is not installed, type the below command,

sudo apt-get install putty-tools

puttygen keyfile.pem -O private -o avdev.ppk

How to download YouTube Playlist

The program ‘youtube-dl’ is currently not installed. You can install it by typing:

sudo apt install youtube-dl

youtube-dl -o '%(playlist)s/%(playlist_index)s - %(title)s.%(ext)s' https://www.youtube.com/playlist?list=PLtaXuX0nEZk9MKY_ClWcPkGtOEGyLTyCO