Mac OS X Tiger in a Nutshell

Command Forms

Table 5-19. bash command forms

Syntax	Effect
cmd &	Execute cmd in background.
cmd1; cmd2	Command sequence; execute multiple cmds on the same line.
(cmd1; cmd2)	Subshell; treat cmd1 and cmd2 as a command group.
cmd1 | cmd2	Pipe; use output from cmd1 as input to cmd2.
cmd1 'cmd2'	Command substitution; use cmd2 output as arguments to cmd1.
cmd1 $(cmd2)	Command substitution; nesting is allowed.
cmd1 && cmd2	AND; execute cmd2 only if cmd1 succeeds.
cmd1 || cmd2	OR; execute cmd2 only if cmd1 fails.
{ cmd1; cmd2 }	Execute commands in the current shell.

Examples

    $ cd; ls                Execute sequentially
    $ (date; who; pwd) > logfile   All output is redirected

    $ sort file | pr -3 | lp      Sort file, page output, then print
    $ vi 'grep -l ifdef *.c'      Edit files found by grep
    $ egrep '(yes|no)' 'cat list'  Specify a list of files to search
    $ egrep '(yes|no)' $(cat list) Same as previous using bash command
                                 substitution
    $ egrep '(yes|no)' $(<list)   Same, but faster
    $ grep XX file && lp file  Print file if it contains the pattern
    $ grep XX file || echo "XX not found"  Echo an error message if pattern
                     not found