Conditional Execution

An AND list has the form 
      command1 && command2
command2 is executed if, and only if, command1 succeeds
An OR list has the form 
      command1 || command2
command2 is executed if, and only if, command1 fails  

A list is a sequence of one or more pipelines separated by one of the operators `;', `&', `&&', or `||', and optionally terminated by one of `;', `&', or a newline.

Of these list operators, `&&' and `||' have equal precedence, followed by `;' and `&', which have equal precedence.

If a command is terminated by the control operator `&', the shell executes the command asynchronously in a subshell. This is known as executing the command in the background. The shell does not wait for the command to finish, and the return status is 0 (true).

Related:

OS X Syntax


© Copyright SS64.com 1999-2014
Some rights reserved