As ferrency suggested in the crisis he describes in "Don't try this at home", composing all the bits of a system command into one line is dangerous, because one of those variables might contain a malicious command.

Instead, consider using the system LIST syntax, e.g.:

#  # add double-quote characters to either end of realname
#  # $realname = '"' . $realname . '"';

  # commented out above line after fruiture pointed out that 
  # system LIST format makes it unnecessary -- and even 
  # wrong, since realname would then be stored with '"' 
  # on either side!

  # run system command, but pass args directly to the 
  # adduser program, rather than booting a shell
  if (!system("adduser",
              $username,
              '-g', '100',
              '-s', '/bin/false',
              '-d', "/home/$username",
              '-p', $encrypted_pass,
              '-e' $expiry_date,
              '-c' $realname
              )
     ) {
     die "trouble adding user: returned non-zero\n";
   }

[download]

This will:

  1. Solve your problem with quotes, since you've added them $realname is passed as a single argument.
  2. Protect you from malicious examples like ferrency pointed out before.

See perldoc -f system.

update: fruiture pointed out that quotes were not needed in system LIST syntax.

In reply to Re: Running System Commans With "" by jkahn
in thread Running System Commands With "" by lostperls

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