I suspect you made the (not unreasonable) assumption that the script was producing no output because the output file /tmp/xx was empty.

Due to the way that output redirection is handled by the shell, the output file is created regardless of whether there is any actual output.

You can use this behaviour to your advantage to quickly create an empty file. Here's an example:

$ ls -l redirect_out
ls: cannot access redirect_out: No such file or directory

$ > redirect_out

$ ls -l redirect_out
-rw-r--r-- 1 ken None 0 Oct 16 14:50 redirect_out

[download]

-- Ken

In reply to Re: output redirection when calling perl from shell - perl -pe "blabla" by kcott
in thread output redirection when calling perl from shell - perl -pe "blabla" by noname

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.