Department of Engineering

IT Services

Summary of Commands

(For any commands not listed below try typing "man" or "man -k" followed by the command name)

File and Directory handling
  • cat stands for concatenate and takes any number of file names as arguments. The contents of the files are printed to the standard output (usually the screen) one after another.

  • more takes any number of files as arguments and displays them one after another on the screen, pausing between screenfulls. Press the <space> bar to continue.

  • tail takes a file as its argument and prints out the last 10 lines of the file.

  • cp copies files, from its first argument to its second.

  • mv renames files, from its first argument to its second.

  • chmod changes the permissions on a file, i.e. who can read, write and execute it. The first arguments determine how the permissions are changed and all successive arguments are files to operate on. (Type man chmod for details).

  • rm deletes files. Once removed, files can never be recovered so use this command with great care.

  • mkdir takes an argument and makes a new directory with that name.

  • rmdir takes a directory name as argument and deletes that directory. This only works if the directory is empty.

  • cd changes the directory you are working in. If called without any arguments it takes you back to your home directory.

  • pwd prints your current working directory.

  • ls lists the files in the current working directory. If you give a different directory as an argument then the files in that directory are listed instead. If you use ls -l a long format listing is produced. Use ls -al to see the `dot files' as well.


  • passwd lets you change your password.

  • date prints the date and time.

  • hostname prints out the name of the machine you are working on.

  • who shows who is logged into the workstations near to you.

  • man takes a unix topic as argument and prints its manual entry. The command man -k string supplies unix topics related to a given string.

  • lp takes file name arguments and prints these files on the line printer.

  • sleep takes a numeric argument and does nothing for that number of seconds.

  • bc is a desk calculator. You type bc on a line by itself and then type in expressions for it to evaluate. Gives the answer to things like 3+4. For real numbers you will have to say scale=10. Finish with C-d.

  • wc takes filenames as arguments and counts the number of characters, words and lines in each.
Job Control
  • fg brings the current background job into the foreground.

  • bg runs the current stopped job (if any) in the background.

  • C-z suspends the current foreground job.

  • The interrupt character is C-c (i.e. hold the control key down and press c).