Linux Commands (Case Sensitive):

​

Basic:

pwd                ==> print the name of current directory   || Ex: pwd

whoami             ==> print the current user                || Ex: whoami

cd [directoryName] ==> enter a directory                     || Ex: cd Music

cd ..              ==> go back to the parent directory       || Ex: cd ..

cp [file]          ==> copy file                             || Ex: cp music.mp3

ls                 ==> list all items in the current folder  || Ex: ls

clear              ==> clears the terminal                   || Ex: clear

mkdir [foldername] ==> makes folder with the specified name  || Ex: mkdir Songs

rmdir [foldername] ==> removes the specified folder          || Ex: rmdir Songs

echo [param]       ==> outputs the value of the variable     || Ex: echo "Hi"

                       or string to stdout                   

tree               ==> lists the files in the current        || Ex: tree 

                       directory in tree like format 

​

For sorting files:

mv [file] [newname]==> rename a file or folder               || Ex: mv exe txt

cat [filename]     ==> reads the specified file              || Ex: cat cmds.txt

tac [filename]     ==> reads the specified file in reverse   || Ex: tac cmds.txt

tail [file, file]  ==> reads first 10 lines of the files     || Ex: tail cmds.txt

zip [file, file]   ==> compresses the specified files        || Ex: zip files

vi [file]          ==> edit file in the terminal             || Ex: vi cmds.txt

gedit [file]       ==> edits the file in text editor         || Ex: gedit cm.txt

nano [file]        ==> edit file in nano editor              || Ex: nano cmds.txt

tar                ==> same as bzip2                         || Ex: tar file

bzip2 -z / -d      ==> compress and decompress files with    || Ex: bzip2 -z cmds

                       the extension "bz2" respectively  

gzip               ==> same as bzip2 but compresses files    || Ex: gzip file

                        with a gz extension.

​

Getting help:

man [command]      ==> show the manual of the command        || Ex: ls man

[command] --help   ==> similar to man but ouputs in terminal || Ex: pwd --help

apropos [word]     ==> search for the word in description    || Ex: aprpos list

                       of all commands

​

More advanced: 

reboot             ==> reboot the system                     || Ex: reboot

which [command]    ==> ouputs the location of the command    || Ex: which ls

su [username]      ==> impersonate as the specified user     || Ex: su root

id                 ==> print user and group information      || Ex: id

hostname           ==>  display or seta computer`s hostname  || Ex: hostname

uname -a          ==> show  all the information of the OS    || Ex: uname -a

exit               ==> exit the current user or the terminal || Ex: exit

shutdown -P +min   ==> shutdowns the system                  || Ex: shutdown -P

​

Networking: 

ifconfig           ==> lists all the network interfaces on   || Ex: ifconfig

                       your machine 

netstat            ==> displays network connections for TCP, || Ex: netstat

                       routing tables, and a number of 

                       network interface and network 

                       protocol statistic

​

For listing hardware:

lscpu             ==> list CPU architecture information      || Ex: lscpu

lsusb             ==> list information about usbs            || Ex: lsusb

lsblk             ==> list block devices                     || Ex: lsblk

lsof              ==> list opened files                      || Ex: lsof

lspci             ==> list PCI devices                       || Ex: lscpi

​

System Administration: 

  User Management:

  who                ==> prints the current logged in users  || Ex: who

  users              ==> shows names of users logged in      || Ex: users

  adduser [username] ==> adds another user                   || Ex: adduser david

  useradd [username] ==> same as adduser but is not preferrd || Ex: useradd david

  deluser            ==> deletes a user                      || Ex: deluser david

  usermod [user]     ==> modify user settings & prefrences   || Ex: usermod david --shell /bin/bash

  passwd [user]      ==> change the password of the user     || Ex: passwd  

  uptime             ==> shows how long the system has been  || Ex: uptime

                         running, number logged on users and 

                         the system load averages       

  visudo             ==> recommended way to edit             || Ex: sudo visudo

                         /etc/sudoers file

  vipw               ==> recommended way to edit /etc/passwd || Ex: sudo vipw

                         file

  systemctl          ==> mangae all the background running   || Ex: sudo systemctl disable ssh

                         services (daemons)

  journalctl         ==> see all the logs for systemctl      || journalctl -xe

  Important Files:

  /etc/passwd     ==> stores information of all the users    || cat /etc/passwd

  /etc/shadow     ==> stores the hashed version of every     || cat /etc/passwd

                    user`s password

ps(Process Status)==> displays currently-running processes   || Ex: ps

ss(Socket Status) ==> used to dump socket statistics and     || Ex: ss

                      displays information 

​

1. ls - used to list the files and directories in a directory

2. cd - used to change the current directory

3. pwd - used to display the current working directory

4. mkdir - used to create a new directory

5. rmdir - used to remove an empty directory

6. rm - used to remove a file or directory

7. touch - used to create a new file

8. cp - used to copy a file or directory

9. mv - used to move or rename a file or directory

10. nano or vim - used to edit text files in the command line

11. cat - used to display the contents of a file

12. less - used to view the contents of a file one page at a time

13. grep - used to search for a specific string of text in a file or multiple files

14. find - used to search for files in a directory

15. chmod - used to change the permissions of a file or directory

16. chown - used to change the owner of a file or directory

17. su - used to switch to the superuser or root account

18. sudo - used to execute a command as the superuser or root account

19. exit - used to log out of the current user account

20. clear - used to clear the terminal screen

21. history - used to display a list of recently executed commands

22. top - used to display the currently running processes and their resource usage

23. ps - used to display the currently running processes

24. kill - used to terminate a running process

25. df - used to display the available and used disk space on a file system

26. du - used to display the size of a directory or file

27. free - used to display the amount of free and used memory in the system

28. ln - used to create a symbolic link between a file or directory

29. tar - used to create and extract archive files

30. gzip and gunzip - used to compress and decompress files

31. ssh - used to securely connect to a remote system

32. scp - used to securely copy files between systems

33. rsync - used to efficiently copy files and directories between systems

34. ping - used to test network connectivity

35. traceroute - used to display the route a packet takes to reach a host

36. netstat - used to display information about network connections and routing tables

37. ipconfig - used to configure network interfaces

38. apt-get - used to manage packages on Debian-based systems

39. yum - used to manage packages on Red Hat-based systems

40. systemctl - used to manage and view system services

1.sudo // meaning superUser do give access to superuser work

    sudo -h // gives the command help 

2.pwd // meaning path of working directory

    pwd <options(-L or -P)> // -L gives path to logical path and -P for physical path

    //-L For example,if existing in a dir /home/symlinked, it's a symlink to /home/realdir; it would display /home/symlinked.

    //-P For example, if existing in a dir /home/symlinked, it's a symlink to /home/realdir; it would display /home/realdir.

3.cd <options(~[username] or .. or -)>

4.ls <options (-R or -a or -lh)>//-R recursive, -a means all including hidden files

    //-lh shows the file size with easy readable format

5.cat // meaning conacat used to conacat files

    cat filename.txt // view the file

    cat > filename.txt // creates a new file and ctrl+D to save the file

    cat file1.txt file2.txt > file3.txt // merges two files

    tac filename.txt // display content of file in reverse order

6.cp // to copy the files and directories

    cp filename.txt destinationPath

    cp filename.txt /home/username/Documents

    cp filename1.txt filename2.txt filename3.txt /home/username/Documents

    cp filename1.txt filename2.txt // copy content of file in another file

    cp -R /home/username/documents /home/username/documents_backup

        // -R copy everything recursively meaning copy whole directory

7.mv // primary use is to move and rename files and directories

    mv filename.txt /home/username/Documents // moves file to this directory

    mv old_filename.txt new_filename.txt // renames the filename

​

8.mkdir // used for creating one or many directries at once and set permission

    // for each one of them

    mkdir [options] directory_name

    mkdir Music // create a directory called Music

    mkdir Music/Songs // create a directory inside Music

    mkdir -p Anime/Movies // create multiple parent directories if needed

    mkdir -m a=rwx [directories] // read and write and execution access

    mkdir -v [directories] // verbose meaning print statement for each directory created

​

9.rmdir // removes empty directory but user must have sudo privilage in parent directory

    rmdir folder_name

    rmdir -p Anime/Movies //if both directores are empty we can delete both by using this flag

10.rm //this command is used to delete files in the directory

    // user performing this command must have write permission

    rm [options] filename.txt

    rm file1.txt file2.txt file3.txt // removes multiple files

    rm -i file1.txt file2.txt file3.txt // prompts for confirmation before deleting file

    rm -r directoryname/ // remvoes file recursively

    rm -f file1.txt file2.txt file3.txt // removes file without any confirmation

​

11.touch // this allows you to create empty file or to modify time stamp

    touch filename.txt // for creating file

    touch filename{1..3}.txt // create multiple file filename1.txt, filename2.txt, filename3.txt

    touch -a filename.txt // changes access time to currenttime

    touch -m filename.txt // chagnes modified time to currenttime

    touch -a -t YYYYMMDDhhmm.ss filename.txt// this will set the acess time as per provided

    touch  file1.txt -r file2.txt // this will copy access and modified time of file2.txt and update in file1.txt

    touch -d '8 Mar' filename.txt // this will set the give string as date and rest will be same as current time

    touch -d '20:10' filename.txt // this will se the time and rest will be same current date   

​

12. stat filname.txt // gives access, modified and created time data etc

​

13.locate // will help to find the file with the name

    locate filename.txt 

    locate -i school // will find all filenames having school word in it

    // -i ignores the case

    locate -i school*notes // finds all files with containing words school and notes

​

14.find // to find file or directory with directory path to look for

    find [directory] -name [filename]

    find /home -name notes.txt // will find notes.txt in home directory and its sub folder

    find -name notes.txt //will find notes.txt in current directory 

    find ./ type d -name directoryname // will find the directory with name

​

15.grep // to find some data in the file

    grep [options] pattern [FILE]

    grep -A2 pattern file_name // print 2 more lines after the pattern match

    grep -B2 pattern file_name // print 2 lines before the pattern match

    grep -C3 pattern file_name // print 3 lines before and after the patten match

    options:

    -i // case insensative search

    -w // search for words only

    -c // counts the total matches

    -r // search in recursive pattern

    -n // prints lines numbers

    -v //this options show the reverse match i.e which don't match

    grep pattern file1, file2, file3

    grep pattern * // search in the all present files

    grep 'query1\|query2' file // serarching for multiple queryies at a time

    egrep 'query1|query2' file 

    grep -e query1 -e query2 file

    grep -E 'query1|query2' file

    grep '^query' file // search the lines which starts with query

    grep '^query1.*query2$' file // finds lines which starts with query1 and endswith query2

# cursor to the front 

ctrl + a

​

# cursor at the end

ctrl + e

​

# clear the current cmd

ctrl + u

​

# Exit or Stop cmd

ctrl + c

​

username ec2-user

sudo su

yum install httpd

service start httpd

chkconfig httpd on