A simple shell command such as
echo a b c consists of the command
itself followed by arguments, separated by spaces.
More complex shell commands are composed of simple commands arranged together in a variety of ways: in a pipeline in which the output of one command becomes the input of a second, in a loop or conditional construct, or in some other grouping.
|• Reserved Words||Words that have special meaning to the shell.|
|• Simple Commands||The most common type of command.|
|• Pipelines||Connecting the input and output of several commands.|
|• Lists||How to execute commands sequentially.|
|• Compound Commands||Shell commands for control flow.|
|• Coprocesses||Two-way communication between commands.|
|• GNU Parallel||Running commands in parallel.|