Do you know what is Linux?

Linux is a name that broadly denotes a family of free and open-source software operating systems built around the Linux kernel. Typically, Linux is packaged in a form known as a Linux distribution for both desktop and server use. Linux works on command line interface (CLI) i.e. most of the work done in Linux is done by typing some set commands on the terminal. Here are a few of those commands which will help you to begin on Linux.

Terminal Control Characters

^h                  backspace erase previously typed characters

^u                  erase entire line of input so far typed

^d                  end-of-input for programs reading from terminal

^s                  stop printing on terminal

^q                  continues printing on terminal

^z                  currently running job; restart with bg or fg

DEL, ^c         kill currently running program and allow clean-up before exiting

^\                   emergency kill of currently running program with no chance of clean-up

Login and Authentication

login             access computer; start interactive session

logout           disconnect terminal session

passwd         change local login password; you MUST set a non-trivial password Information

date               show date and time

history           list of previously executed commands

pine               send or receive mail messages

msgs             display system messages

man               show on-line documentation by program name

info                on-line documentation for GNU programs

w, who           who is on the system and what are they doing

who am i        who is logged onto this terminal

top                 show system status and top CPU-using processes

uptime           show one line summary of system status

finger             find out info about a user@system

File Management

cat                 combine files

cp                  copy files

ls                   list files in a directory and their attributes

mv                 change file name or directory location

rm                  remove files

ln                   create another link (name) to a file

chmod           set file permissions

des                encrypt a data file with a private key

find                find files that match specified criteria

locate            finds all the files on the file system, starting at the root, that contain all or any part of the search criteria

Display Contents of Files

cat                 copy files to display device

vi                   screen editor for modifying text files

more              show text file on display terminal with paging control

head              show first few lines of a file(s)

tail                  show last few lines of a file; or reverse line order

grep               display lines that match a pattern

lrp                  send files to line printer

pr                   format files with page headers, multiple columns etc.

diff                 compare two files and show differences

cmp               compare two binary files and report it differently

od                  display binary file as equivalent octal/hex codes

file                 examine file(s) and tell you whether text, data, etc.

wc                 count characters, words, and lines in a file

Directories

cd                  change to new directory

mkdir             create new directory

rmdir              remove empty directory (remove files first)

mv                  change name of directory

pwd                show current directory

Devices

df                   summarize free space on disk device

du                  show disk space used by files or directories

Special Character Handling for C-shell

*                  match any character in a file name

~user          shorthand for home directory of “user”

$name        substitute value of variables “name”

\                  turn off special meaning of character that follows

‘                  In pairs, quote string with special chars, except !

“                  In pairs, quote string with special chars, except !, $

`                  In pair, substitute output from enclosed command

Controlling Program Execution for C-shell

&                run job in background

DEL, ^c      kill job in foreground

^z               suspend job in foreground

fg                restart suspended job in foreground

bg               run suspended job in background

;                  delimit commands on same line

()                 group commands on same line

!                  re-run earlier commands from history list

ps                print process status

kill               kill background job or previous process

nice            run program at lower priority

at                run program at later time

crontab       run program at specified intervals

limit             see or set resource limit for programs

alias            create alias name for program (in .login)

sh, csh        execute command file