It's also worth pointing out that

• you don't need to use curly braces to bracket an arguement to eval if that arguement is a simple string.
• and you don't need to eval a back-ticked string.

  When perl encounters a back-ticked string, it passes the contents of the string (after interpolating any embedded vars) to a system shell for processing, captures any output from the command, and returns that to the calling program once the command completes. eg.

  print "`set tmp` returned:", `set tmp`, $/;

  results in

  `set tmp` returned:TMP=D:\TEMP

  on my system.

  If you need to know the exit status of the command being issued, then you need to look at $? see perlman:perlvar. eg.

  print "`set tmp` returned:", `set tmp`, " and had an exit code of:$?",
  +$/;
  print "`set non-existant-env` returned:", `set non-existant-env`, " an
  +d had an exit code of:$?",$/;
  [download]

  gives

  `set tmp` returned:TMP=D:\TEMP
   and had an exit code of:0
  Environment variable non-existant-env not defined
  `set non-existant-env` returned: and had an exit code of:256
  [download]

Finally, you're almost certainly better of using the system function (see perlamn:perlfunc), as Aristotle suggest's, but don't be confused by the => ! This is colloqually known as 'the fat comma', and when used as Aristotle has, it is simply equivalent to a comma, and is used here rather than a comma simply for emphasis. I point this out as I spent several hours searching the docs trying to find out what it meant when I first encountered it in a reply to one of my questions.