what is #!/usr/local/bin/perl in perl program

The perl executable, normally installed in /usr/bin or /usr/local/bin on your machine, is also called the perl interpreter .

Every Perl program must be passed through the Perl interpreter in order to execute. The first line in many Perl programs is something like:

    #!/usr/bin/perl

For Unix systems, this #! (hash-bang or shebang) line tells the shell to look for the /usr/bin/perl program and pass the rest of the file to that program for execution. Sometimes you'll see different pathnames to the Perl executable, such as /usr/local/bin/perl .