Does exactly the same thing asexec LIST, except that a fork is done first, and the parent process waits for the child process to exit. 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 toexecvp, 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 (seeperlport). To be safe, you may need to set$| ($AUTOFLUSH in English) or call theautoflush() method ofIO::Handle on any open handles.
The return value is the exit status of the program as returned by thewait call. To get the actual exit value, shift right by eight (see below). See also"exec". This isnot what you want to use to capture the output from a command, for that you should use merely backticks orqx//, as described in"`STRING`" in perlop. Return value of -1 indicates a failure to start the program or an error of the wait(2) system call (inspect $! for the reason).
If you'd like to makesystem (and many other bits of Perl) die on error, have a look at theautodie pragma.
Likeexec,system allows you to lie to a program about its name if you use thesystem PROGRAM LIST syntax. Again, see"exec".
SinceSIGINT andSIGQUIT are ignored during the execution ofsystem, if you expect your program to terminate on receipt of these signals you will need to arrange to do so yourself based on the return value.
@args = ("command", "arg1", "arg2");system(@args) == 0 or die "system @args failed: $?"If you'd like to manually inspectsystem's failure, you can check all possible failure modes by inspecting$? like this:
if ($? == -1) { print "failed to execute: $!\n";}elsif ($? & 127) { printf "child died with signal %d, %s coredump\n", ($? & 127), ($? & 128) ? 'with' : 'without';}else { printf "child exited with value %d\n", $? >> 8;}Alternatively, you may inspect the value of${^CHILD_ERROR_NATIVE} with theW*() calls from the POSIX module.
Whensystem's arguments are executed indirectly by the shell, results and return codes are subject to its quirks. See"`STRING`" in perlop and"exec" for details.
Sincesystem does afork andwait it may affect aSIGCHLD handler. Seeperlipc for details.
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