You seem to be confusing just what a shell is. A shell is just another program. So bash is a program that runs in a process, as is ksh, as is csh, as is ls, as is ps, as is perl, as is python, etc. Some shell commands are 'built-ins', like cd, and those do not require a separate process. Others that can be shell commands, which you might inaccurately call an "OS command", are programs like ls and ps which have nothing to do with a shell - it is just that we often invoke them from a shell.

You can't directly 'source' the ls or ps programs for example, they are binary (ELF) executables that run in a separate process. You can source the command to invoke them, but they will still run in a different process to your shell. The perl program is no different.

Fortunately there are Perl equivalents to many UNIX programs and utilities that you might call from a shell, see UNIX 'command' equivalents in Perl.

In reply to Re: How to execute commands in the same shell as Perl script by cdarke
in thread How to execute commands in the same shell as Perl script by bhagperl

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.