Both backquotes and system should pass their argument to the shell, which will do the same thing with that. Therefore they should not behave differently up to the point where the command has started up.

This suggests to me that the difference in behaviour is in the external command itself. One wild guess is that the external command is testing whether or not it is talking to a tty, and then dying if not? (And then a poorly written error-report somewhere along the chain is lying to you about what is wrong...) You can check this by seeing if it will refuse to let its output be piped into another program. If this is the problem, you should be able to fix the problem with Expect or the older Comm.pl library. (You might have to dig around for a version/variation that will work on 5.004_04.)

Good luck...

In reply to Re: Inconsistent system call from backticks vs system() by tilly
in thread Inconsistent system call from backticks vs system() by Tanalis

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.