Thread fork stdout
(9 answers)
Opened by Gast at 2009-01-15 21:14
Diese ergoogelte Seite hat mich veranlasst dazu nachzufragen:
How do I start a process in the background? You could use system("cmd &") or you could use fork as documented in fork, with further examples in the perlipc manpage. Some things to be aware of, if you're on a Unix-like system: STDIN, STDOUT and STDERR are shared Both the main process and the backgrounded one (the ``child'' process) share the same STDIN, STDOUT and STDERR filehandles. If both try to access them at once, strange things can happen. You may want to close or reopen these for the child. You can get around this with opening a pipe (see open) but on some systems this means that the child process cannot outlive the parent. Signals You'll have to catch the SIGCHLD signal, and possibly SIGPIPE too. SIGCHLD is sent when the backgrounded process finishes. SIGPIPE is sent when you write to a filehandle whose child process has closed (an untrapped SIGPIPE can cause your program to silently die). This is not an issue with system("cmd&"). Zombies You have to be prepared to ``reap'' the child process when it finishes $SIG{CHLD} = sub { wait }; See Signals for other examples of code to do this. Zombies are not an issue with system("prog &"). Source: Perl FAQ: System Interaction Copyright: Copyright (c) 1997 Tom Christiansen and Nathan Torkington. Link darf ich vermutlich als Gast keinen einfügen. |