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UNIX Tutorial


Typographical conventions

In what follows, we shall use the following typographical conventions:

  • Characters written in bold typewriter font are commands to be typed into the computer as they stand.
  • Characters written in italic typewriter font indicate non-specific file or directory names.
  • Words inserted within square brackets [Ctrl] indicate keys to be pressed.

So, for example,

ls anydirectory [Enter]

means "at the UNIX prompt % or $, type ls followed by the name of some directory, then press the key marked Enter"

Don't forget to press the [Enter] key: commands are not sent to the computer until this is done.

Note: UNIX is case-sensitve, so LS is not the same as ls.

The same applies to filenames, so myfile.txt, MyFile.txt and MYFILE.TXT are three seperate files. Beware if copying files to a PC, since DOS and Windows do not make this distinction.

Unix Shell Advanced

List of unix shells

  • Bourne shell (sh)
  • C shell (csh)
  • TC shell (tcsh)
  • Korn shell (ksh)
  • Bourne Again shell (bash)
  • Z shell (zsh)

To check current login shell

echo $0

cat /etc/shells 

# to change shell for `username`
usermod -s /bin/bash <username>

# alternate method with chsh 
chsh -s /bin/bash <username>