Signal Handling

• Every process has a signal handler table

• Copied on fork

• Some parts of it are preserved across exec

• What does nohup do?

• It just sets the HUP entry to say 'ignore this signal'

• Then it looks at its arguments and execs the command they specify

• If a HUP signal is sent to the process, it will be ignored

        #!/bin/perl
        @ARGV or die "Usage: nohup command [args...]\n";
        $SIG{HUP} = 'IGNORE';
        exec @ARGV or die "Couldn't exec $ARGV[0]: $!\n";

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Copyright © 2003 M. J. Dominus