Run a separate program
system PROGRAM LIST
Does exactly the same thing as ``
exec LIST'' except that a fork is done first, and the parent process
waits for the child process to complete. Note that argument processing varies depending on the number of arguments.
If there is more than one argument in LIST, or if LIST is an array
with more than one value, starts the program given by the first element of the list with arguments given by the
rest of the list. If there is only one scalar argument, the argument is checked for shell metacharacters, and if
there are any, the entire argument is passed to the system's command shell for parsing (this is
on Unix platforms, but varies on other platforms). If there are no shell metacharacters in the argument, it is
split into words and passed directly to
execvp(), which is more efficient.
The return value is the exit status of the program as returned by the wait() call. To
get the actual exit value divide by 256. See also exec. This is NOT what you want
to use to capture the output from a command, for that you should use merely backticks or qx//,
as described in `STRING`.
Like exec(), system() allows you to lie to a program about
its name if you use the ``
system PROGRAM LIST'' syntax. Again, see exec.
Because system() and backticks block
killing the program they're running doesn't actually interrupt your program.
@args = ("command", "arg1", "arg2");
system(@args) == 0
or die "system @args failed: $?"
You can check all the failure possibilities by inspecting
$? like this:
$exit_value = $? >> 8;
$signal_num = $? & 127;
$dumped_core = $? & 128;
When the arguments get executed via the system shell, results and return codes will be subject to its quirks
and capabilities. See `STRING` and exec for details.