Harry:
On Mon, Jan 05, 2015 at 06:20:06PM -0500, Harry Putnam wrote:
> When running shell commands from perl script with an open() instead of
> system() or exec how is the return value snagged.
>
> I guess, if it doesn't die, it worked but how to snag that information
> and at what point?
>
> ------- 8< snip ---------- 8< snip ---------- 8<snip -------
> #!/usr/local/bin/perl
>
> use strict;
> use warnings;
>
> my $log = '/home/harry/some.log';
> my $cmd = 'rsnapshot -c rsnap_Home.conf hourly';
>
> open my $fh, '>', "$log" or die
> "Can't open $log: $!";
>
> open my $ch, '-|', "$cmd" or die
> "Can't run $cmd: $!";
>
> while (<$ch>) {
> print;
> print $fh;
> }
>
> close $fh;
> close $ch;
>
> __END__
You can check the exit status of a pipe after closing it. You
should also be checking the return value of the close because it
might indicate a problem closing the pipe which might affect the
exit status, for example.
perldoc -f close
> If the filehandle came from a piped open, "close" returns false
> if one of the other syscalls involved fails or if its program
> exits with non-zero status. If the only problem was that the
> program exited non-zero, $! will be set to 0. Closing a pipe
> also waits for the process executing on the pipe to exit--in
> case you wish to look at the output of the pipe afterwards--and
> implicitly puts the exit status value of that command into $?
> and "${^CHILD_ERROR_NATIVE}".
So for example...
unless (close $pipe) {
my ($errno, $child_error) = ($!, $?);
if ($errno == 0) {
# Closing the pipe succeeded, but the exit status was
# non-zero.
my $signal = $child_error & 127;
my $status = $child_error >> 8;
handle_pipe_exit($signal, $status);
} else {
# One or more system calls failed when attempting to
# close the pipe. $! should be set appropriately. I don't
# know if you can rely on the process having exited/died
# or on the exit status being set.
handle_pipe_exit_error($errno);
}
};
Regards,
--
Brandon McCaig <bamcc...@gmail.com> <bamcc...@castopulence.org>
Castopulence Software <https://www.castopulence.org/>
Blog <http://www.bamccaig.com/>
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q{Vg qbrfa'\''g nyjnlf fbhaq gung jnl.};
tr/A-Ma-mN-Zn-z/N-Zn-zA-Ma-m/;say'
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