Good, but not sufficient. Input may come from a pipe or a file, so you also should check STDOUT. But even that is not sufficient, because STDOUT could be redirected or piped, too, so you may also want to check STDERR. And, you may already have guessed that, even that is not sufficient, as also STDERR can be piped or redirected.

If you have a dual-mode script that can work both as a daemon ("background process") and as an interactive command, use a command line switch for the daemon mode. Make the daemon starter (daemontools, init, srvany.exe) pass that switch to your command. Alternatively, use a symbolic link and decide based on $0, or use two scripts that have their shared code in one or more modules.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

In reply to Re^4: Detecting forground and background process by afoken
in thread Detecting forground and background process by astroboy

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.