First, it's not being called in list context. That means something else. I call this the multiple argument form.

When you use the single argument form, system expects a shell command and will launch a shell to execute the command*, so 

system('echo $PATH');

[download]

is the same as 

system('/bin/sh', '-c', 'echo $PATH');

[download]

The shell expands $PATH, and in turn, does 

system('echo', '/foo:/bar');

[download]

which is quite different than your 

system('echo', '$PATH');

[download]

You must either use the shell 

system('echo $PATH');

[download]
system('/bin/sh', '-c', 'echo $PATH');

[download]

or you must do what it would do 

system('echo', $ENV{PATH});

[download]

My code is supposed to set $PATH, then run a command on the same line, in the same shell.

You should start by launching a shell, then! 

system('PATH=/foo prog arg');

[download]

Or not. This is something you can do yourself quite easily. 

local $ENV{PATH} = '/foo';
system('prog', 'arg');

[download]

* — As an optimisation, Perl avoids launching a shell when it's obvious that the shell isn't needed.

In reply to Re: System() in list mode? by ikegami
in thread System() in list mode? by 1337John

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.