In Perl, how can I do a non-blocking system call?

In Perl, without using the Thread library, what is the simplest way to spawn off a system call so that 开发者_开发问答it is non-blocking? Can you do this while avoiding fork() as well?

EDIT Clarification. I want to avoid an explicit and messy call to fork.

Do you mean like this?

system('my_command_which_will_not_block &');

As Chris Kloberdanz points out, this will call fork() implicitly -- there's really no other way for perl to do it; especially if you want the perl interpreter to continue running while the command executes.

The & character in the command is a shell meta-character -- perl sees this and passes the argument to system() to the shell (usually bash) for execution, rather than running it directly with an execv() call. & tells bash to fork again, run the command in the background, and exit immediately, returning control to perl while the command continues to execute.

The post above says "there's no other way for perl to do it", which is not true.

Since you mentioned file deletion, take a look at IO::AIO. This performs the system calls in another thread (POSIX thread, not Perl pseudothread); you schedule the request with aio_rmtree and when that's done, the module will call a function in your program. In the mean time, your program can do anything else it wants to.

Doing things in another POSIX thread is actually a generally useful technique. (A special hacked version of) Coro uses it to preempt coroutines (time slicing), and EV::Loop::Async uses it to deliver event notifications even when Perl is doing something other than waiting for events.