playing with "$@"

As you may know, in sh, $0, $1, $2, $3... $9, $* and $@ are special variables holding the command line arguments.

$0 is the name of the program and $1 ... $9 the program parameters.

$# is a number: the count of all arguments (starting from $1, unlike argc in C).

$* is a concatenation of $1 ... $9 with spaces.

$@ is an array, not just one string, but a list of strings:


Even though `$@' was quoted, printf received multiple arguments.

You can edit $1 -> $9 with the `set' built-in command:

• `set "$@"' does not change anything.
  
• `set new "$@"' insert `new' before all the arguments,
  
• `set "$1" "$2"' keeps only $1 and $2,
  

And the `shift' built-in command:

• `shift' removes the first argument from the argument stack (or error).
  
• `shift 2' removes the first 2 arguments from the argument stack.
  

The first argument is $1, but what about the last?


This last will take all $@ values until the end and keep the last value after the loop.

If you are using these a lot, you probably should use a programming language. ;)