Special Variables
Most shell scripts understand command-line parameters and interact with the commands that they run. To take your scripts from simple lists of commands to more flexible programs, you need to know how to use the special Bourne shell variables. Using special variables is not much different than using any other shell variable (see Environment and Shell Variables), but you cannot change the value of certain special variables.
After reading the next few sections, you will understand why shell scripts accumulate many special characters as they are written. If you're trying to understand a shell script and you come across a line that looks completely incomprehensible, pick it apart piece by piece.
$1, $2, ...
$1, $2, and all variables named ...
Get How Linux Works now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
