Unix Freq used Commands

Unix Commands

 

  • Command : alias
    • Function : allow a string to be substituted for a word when it is used as the first word of a simple command.
    • Syntax : alias [-p] [name[=value] …]
    • Example : alias cls=’clear’

                cls

  • Command : cat
    • Function : To view / display a file.
    • Syntax : cat (file name)
    • Example : cat a1.txt
  • Command : cd
    • Function: To change the directory.
    • Syntax : cd (directory name)
    • Example : cd IT1
  • Command : clear
    • Function: To clear the screen.
    • Syntax : clear
  • Command : Copy / cp
    • Function : To copy the directory and its file to another directory. / to copy file
    • Syntax : cp –r (source directory) (destination directory)
    • Example : cp –r IT1/ IT2
    • Syntax : cp (source filename) (destination filename)
    • Example : cp a1.txt a2.txt
  • Command : date
    • Function : To print date and time.
    • Syntax : date
  • Command : finger
  • Command : fold
    • Function : folding contents of specified files, or standard input. (default 80 columns.)
    • Syntax : fold –w <number of columns> –s <filename>
    • Example : fold –w 5 –s a1.txt
  • Command : history
    • Function : To view the commands which was executed
    • Syntax : history
  • Command : listing directory
    • Function : To list only the directories with in a directory.
    • Syntax : ls -d
  • Command : ls
    • Function : To list the contents of a directory.
    • Syntax : ls
  • Command : man
    • Function : Show manual for a command
    • Syntax : man (command)
    • Example : man cat
  • Command : mkdir
    • Function: To create a directory.
    • Syntax : mkdir (directory name)
    • Example : mkdir CIVIL
  • Command : move / mv
    • Function :To rename a directory / file
    • Syntax : mv (directory 1) (directory 2)
    • Example : mv CIVIL IT
    • Syntax : mv (old file name) (new file name)
    • Example : mv a1.txt a2.txt
  • Command : passwd
    • Function : to change current user password
    • Syntax : passwd
  • Command : ps
    • Function : Displays Process status. Result contains four columns of information – pid (unique process id), tty (terminal), time (amount of time the process has been running) and cmd (name of the command that launched the process)
    • Syntax : ps
  • Command : pwd
    • Function : To print present working directory. / To display complete path of the working directory.
    • Syntax : pwd
  • Command : rm
    • Function : to delete or remove files
    • Syntax : rm <filename>
    • Example : rm a1.txt
  • Command : rd / rmdir
    • Function : To remove directory.
    • Syntax : rmdir (empty directory name)
    • Example : rmdir IT1
    • Syntax : rmdir –r (non-empty directory name)
    • Example : rmdir –r IT2
  • Command : tar
    • Function : to create compressed archive files and that can be moved easily from one disk to another disk or machine to machine.
    • Syntax : tar <tar_file_name> <name of directory to be compressed>
    • Example : tar a1.tar /home/exam01/
  • Command : top
    • Function : Display processor activity of server and tasks managed by kernel in real-time.
    • Syntax : top
  • Command : wait
    • Function : Wait for process to terminate, and return its exit status
    • Syntax : wait <pid>
  • Command : who
    • Function : To find out who is logged in. / To print who is using the system presently.
    • Syntax : who
  • Command : whoami
    • Function : Display user name.
    • Syntax : whoami