Presuming you're asking how to specify the name of the file? To do what you're doing here I would do: 
my $userid = "rsennat";    # assume userid is set to a var

my $string = "$str1,$str2";

# NB: using double quotes so that the $userid is interpolated
# Single quotes would protect the literal string like \$userid
my $tmp_file = "/tmp/$userid";

open(TMPFILE, ">> $tmp_file") ||
  die "Can't write to '$tmp_file': $!\n";
print TMPFILE $string;
close(TMPFILE);

[download]
You're better off opening a file and printing to it straight from Perl than relying on shelling out to echo or another command to do the same thing - shelling out (using system or *cough* backticks) uses another process, is less portable and takes away your script's full control over what you're doing.

The only minus with doing it this way is that you have 3 lines of code instead of 1, but I'd take that hit any day for the improvement it makes to the efficiency, security, reliability and portability of the program!

In reply to Re: put data in dynamic file by serf
in thread put data in dynamic file by rsennat

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.