I just write a perl script named First.pl. Everytime I run it, I need to type " perl First.pl" or
"./First.pl". My question is how to make my script become a command ?. E.x: I can type
" First.pl" to execute it.

Thank you,

this has nothing to do with perl whatsoever, and besides, it already IS executable. "./First.pl" means you are executing it directly. What you actually mean is how can i not have to type the "./" part... you would need to have the location of that directory in your path variable, however that is a REALLY bad idea... just don't. you type ./ first to specify it is in the current directory, and these conventions exist for good reasons. this file is 100% as executable as any other command on your system. don't break conventions unless you have a handful of genuine reasons, and "because you want to" really doesn't cut it... that's the way to bad habits and poorly managed systems.

You could always copy it to somewhere like /usr/local/bin and then you could run it as "First.pl".