Please add use strict; to the top of your program. Then Perl will tell you what happens:

Global symbol "$JAVA_HOME" requires explicit package name at 564926.pl
+ line 4.

[download]

Perl sees the variable $JAVA_HOME and replaces it with its value, which is empty. The strict pragma prevents you from inventing variables.

If all you want to do is get at the value of environment variables, these are all available in the %ENV hash:

my $res = $ENV{JAVA_HOME};

[download]

If you want to know how to pass strings that look like variable names to the shell via backticks, you need to quote the special chars:

my $res = `echo \$JAVA_HOME`;

[download]

In reply to Re: taking an output in a variable by Corion
in thread taking an output in a variable by s_gaurav1091

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.