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Some general things to keep in mind about UNIX

*** UNIX is case sensitive so myfile.txt and MyFile.txt do not mean the same thing.

*** UNIX is stable because every program is handled by the core operating system (known as the kernel) as a distinct process with its own little chunk of dedicated memory. If that program runs into trouble, it dies, but does not affect the affect the kernel or the other programs running on the computer.

*** You communicate with a UNIX computer through a comand program known as a shell. The shell interprets comands that you type on the keyboard.

*** There are actually many different shells available for UNIX computers, and on some systems you can choose the shell in which you wish to work.


*** UNIX commands are short and cryptic like vi or rm. Computer geeks like it that way; you will get used to it.

*** Every command has a host of modifiers which are generally single letters preceded by a hyphen. Capital letters have different functions than small letters, often completely unrelated.

*** A comand also generally requires an argument, meaning some file on which it will act.


*** You can substitute the * as a wildcard symbol for any part of a filename in any command.

*** If you make a typing mistake in UNIX, you are doomed!

*** Actually there are several ways to edit the text on a command line:

  • the delete key removes the character that you just typed
    However, exactly what key on your particular keyboard (using a particular Telnet program to connect to a particular server which is running a particular version of UNIX using a particular shell) will function as delete is often a mystery.
  • ctrl-W erases the previous word
  • ctrl-U erases the whole command line


*** You type Control characters by holding down the key while also pressing the speicified character.


*** Some other handy Control commands:
(most of these work most of the time)
  • ctrl-S suspends (halts) output scrolling up on your terminal screen
  • ctrl-Q resumes the typing of output on your screen
  • ctrl-C will abort a process
  • ctrl-Z suspends the current program
    [You can resume the suspended program by giving the fg (foreground) command]
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Using Computers for Molecular Biology
Stuart M. Brown, Ph.D, RCR, NYU Medical Center
Comments to: browns02@mcrcr.med.nyu.edu