Alternatively, use the "full path" to sh, and the target command. use "-c" to parse from the command options (instead of from the standard input).

These are standard "sh" parameters, nothing to do with perl.

system("/bin/sh -c  /bin/uname -a")
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Update::

To properly pass the "-a" parameter to uname above, the command needs to be written as :

 system("/bin/sh -c  \"/bin/uname -a\"") ; 
  # or  (more readable):
   system(qq(/bin/sh -c  "/bin/uname -a"))
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