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 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`" in perlop. Return value of -1 indicates a failure to start the program (inspect $! for the reason).
system allows you to lie to a program about its name if you use the
system PROGRAM LIST syntax. Again, see "exec".
system and backticks block
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;