Question

I was wondering if there is a way to get Linux commands with a perl script. I am talking about commands such as cd ls ll clear cp

Answer 1

You can execute system commands in a variety of ways, some better than others.

• Using system();, which prints the output of the command, but does not return the output to the Perl script.
• Using backticks (“), which don’t print anything, but return the output to the Perl script. An alternative to using actual backticks is to use the qx(); function, which is easier to read and accomplishes the same thing.
• Using exec();, which does the same thing as system();, but does not return to the Perl script at all, unless the command doesn’t exist or fails.
• Using open();, which allows you to either pipe input from your script to the command, or read the output of the command into your script.

It’s important to mention that the system commands that you listed, like cp and ls are much better done using built-in functions in Perl itself. Any system call is a slow process, so use native functions when the desired result is something simple, like copying a file.

Some examples:

# Prints the output. Don't do this.
system("ls");

# Saves the output to a variable. Don't do this.
$lsResults = `ls`;

# Something like this is more useful.
system("imgcvt", "-f", "sgi", "-t", "tiff", "Image.sgi", "NewImage.tiff");

This page explains in a bit more detail the different ways that you can make system calls.