Since many basic tasks can be done graphically, the command line interface
became less important. There are still some occasions, where it is very
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
In UNIX a script can be named arbitrarily and the full name has to
be used, e.g. file initall.pl has to be called as
The basic form of a system command is
COMMAND OPTIONS ARGUMENTS,
name of the command
special flags or switches which modify the command
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).