Some preliminary trials show you're probably right (though I still don't see what could be different on these two systems... maybe a different version of some IPC::* module?). In any case, I was experimenting with the list form of exec for other reasons, and I finally made it through the gotchas:
my @cmd =
('perl',
'-e
print "child: id after exec: $$\n";
print "child: sees processes...\n " ,
grep { m/perl/ }
`ps ax` , "\n";
',
);
print "parent: pre-fork id $$\n";
if ( my $pid = fork ) {
# this is parent code
print "parent: post-fork id $$\n";
print "parent: return from fork is: $pid\n";
sleep 3;
print "parent: still here, with id $$\n";
print "parent: sees processes...\n " ,
grep { m/perl/ }
`ps ax` , "\n";
} else {
# this is child code
die "cannot fork: $!" unless defined $pid;
print "child believes it is: $$\n";
exec {$cmd[0]} @cmd;
}
The gotchas:
- You use the command name first ("indirect object" syntax, ala printing to a file handle), *and* have the command name again inside the list. The second one is what appears in the process listing, the first is the program that's actually run.
- From the shell, you typically do a perl -e 'some code', but if you're going around the shell, those single quotes on the string fed to "-e" just get in the way: @cmd = ('perl', q{-e some code }).