Since many basic tasks can be done graphically, the command line interface became less important. There are still some occasions, where it is very useful:

A sequence of system commands can be written into a file (called ``shell script'' or ``batch file'') and called like a program. Typical command languages contain special programming constructs like tests and loops. This allows to automate rather complex tasks.

In case of system problems (e.g. hardware defects, incorrect startup scripts) system commands are helpful to isolate or fix the problem.

Especially on UNIX systems exist a set of small, but useful utilities, which can be combined to solve common problems in one line.

In DOS a batch file has the extension .bat and is called without the extension, e.g. file initall.bat is executed with initall.

In UNIX a script can be named arbitrarily and the full name has to be used, e.g. file has to be called as

The basic form of a system command is



COMMAND name of the command
OPTIONS special flags or switches which modify the command
ARGUMENTS objects, the command operates on

In the line

dir /o /p c:\windows

dir is the command, meaning ``list all files in the given directory'',
c:\windows is the directory to list
/o /p are options meaning ``display in alphabetic order'' (/o) and ``show one screen at a time'' (/p).

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Peter Junglas 8.3.2000