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 /bin/sh -c 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.
Beginning with v5.6.0, Perl will attempt to flush all files opened for
output before any operation that may do a fork, but this may not be
supported on some platforms (see perlport). To be safe, you may need
to set $| ($AUTOFLUSH in English) or call the autoflush() method
of IO::Handle on any open handles.
The return value is the exit status of the program as returned by the
wait call. To get the actual exit value shift right by eight (see below).
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 perlop/"`STRING`". Return value of -1
indicates a failure to start the program (inspect $! for the reason).
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 SIGINT and SIGQUIT,
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;
or more portably by using the W*() calls of the POSIX extension; see perlport for more information.
When the arguments get executed via the system shell, results and return codes will be subject to its quirks and capabilities. See perlop/"`STRING`" and /exec for details.