Unix tcsh - alias using command line argument $1 versus \!:1
In Unix (tcsh), I've referenced command line arguments in my aliases with two different notations - $1 and \!:1.
But I noticed that if I try to save $1 to an environment variable, it doesn't get saved. However \!:1 does get saved.
alias hear 'setenv x \!:1 && echo $x'
--> hear that
that
--> echo $x
that
alias oh 'setenv x $1 && echo $x'
--> oh no
no
--> echo $x
Nothing shows up on the echo of $x when $1 is used to store the value. What is the reason for this?
Answer
$1 returns the first argument passed to the script that contains the alias command. So if you are calling it from the command line, it will return nothing.
\!:1 returns the first argument passed to the aliased command, so that is clearly what you should be using.