Basic Linux Commands

mkdir - make directories

eg:- mkdir vishnu

cd - change directories. Use cd to change directories. 

eg:- cd /home/vishnu/test/

mv- used to move files or directories and also used to chage its name 

eg:- mv test.txt /home/vishnu/example/

  mv test.txt example.txt

pwd - print working directory or present working directory

eg:- pwd

/home/vishnu/test/example/

rmdir - Remove an existing directory

rm -rf

eg:- rmdir test

rm -rf test

chown - change file owner and group

eg:- chown vishnu.vishnu example.txt

  chown vishnu. * -R

  chown vishnu. example.txt

chgrp - change group 

eg:- chgrp vishnu text.txt

  chgrp vishnu example

 chmod - change file access permissions

eg:- chmod 644 test.txt

  chmod 777 example

usage;- chmod [ .. ] file/folder

u - User who owns the file. 

g - Group that owns the file. 

o - Other. 

a - All. 

r - Read the file. 

w - Write or edit the file. 

x - Execute or run the file as a program. 

Numeric Permissions: 

CHMOD can also to attributed by using Numeric Permissions: 

400 read by owner 

040 read by group 

004 read by anybody (other) 

200 write by owner 

020 write by group 

002 write by anybody 

100 execute by owner 

010 execute by group 

001 execute by anybody 


ls - Short listing of directory contents

eg:- ls 

  ls -la

usage:-

-a list hidden files 

-d list the name of the current directory 

-F show directories with a trailing '/' 

  executable files with a trailing '*' 

-g show group ownership of file in long listing 

-i print the inode number of each file 

-l long listing giving details about files and directories 

-R list all subdirectories encountered 

-t sort by time modified instead of name 


cp - Copy files

eg:- cp text.txt /vishnu/example/

  cp -pr example /home/folders/

cal month year - Prints a calendar for the specified month of the specified year.

clear - Clears the terminal screen.(ctrl + l)

cmp file1 file2 - Compares two files, reporting all discrepancies. Similar to the diff command, though the output format differs.

diff file1 file2 - Compares two files, reporting all discrepancies. Similar to the cmp command, though the output format differs.

passwd - change password

Linux Filesystem Management

df :- free disk space 

du :- disk usage 

du -sh :- disk usage in human readable format

cat /proc/swap :- see swap details 

free- free memory usage 

cat /proc/meminfo :- get info about RAM in ur system 

fdisk :- Used to fix or create partitions on a hard drive 

mount :- Used to mount a filesystem. 

umount :- Unmounts a filesystem

File compression, backing up and restoring

gunzip :- unzip - unzip a gz file. 

gzip :-gzip - zip a file to a gz file. 

tar :- Can store files on tapes. 

Usage: tar -cvf - Archive copy groups of files 

tar -xzvf test.tar.gz 

zip :-zip - make a zip file. 

grep :- grep pattern filename

File editing and managing tools

emacs :-Full screen editor.

gitview :-A hexadecimal or ASC file viewer.

Head:- head linuxdoc.txt - Look at the first 10 lines of linuxdoc.txt.

Jed:- Editor

less :- Used to view files.

more :- Used to view files.

pico :-Simple text editor.

tail :-tail linuxdoc.txt - Look at the last 10 lines of linuxdoc.txt.

vi :-Editor with a command mode and text mode. Starts in command mode.

Vim :- advanced text editor

Cat :- file viewer 

Linux Process management

ps :- To see currently running process 

kill :- To stop any process by PID i.e. to kill process 

eg:- kill process id 

killall :- To stop processes by name i.e. to kill process 

eg:- killall firefox 

ps -ag :- To get information about all running process 

ps aux :- To display the owner of the processes along with the processes 

top :- To see currently running processes and other information like memory and CPU usage with real time updates. 

pstree :- To display a tree of processes 

skill :- Report process status. 

gitps :- a graphical process viewer and killer program