Re^4: Capture::Tiny alternative

Yeah, sure. when I get something to show I will put it here.

Meanwhile here is example of how simple script using Perl IPC to read from external program may hangs :


$ cat test.pl

my $cmd = '/usr/sbin/sshuttle -v -D -r  vagrant@127.0.0.1 192.168.0.0/24';

open(OUT, "$cmd 2>&1 |") || die "can't fork: $!";

while (my $l = <OUT>) {
  print $l;
}

When I run test.pl it hangs:

$ perl test.pl
Starting sshuttle proxy.
Listening on ('127.0.0.1', 12300).
c : connecting to server...
vagrant@127.0.0.1's password:
c : connected.
Connected.

...

^C # I have to enter control C to finish my script

When run the same command directly, it does not hang:


$ /usr/sbin/sshuttle -v -D -r  vagrant@127.0.0.1 192.168.0.0/24
Starting sshuttle proxy.
Listening on ('127.0.0.1', 12300).
c : connecting to server...
vagrant@127.0.0.1's password:
c : connected.
Connected.
$ # finishes without interruption ..

Sshutle information could be found here - https://github.com/apenwarr/sshuttle
But I provide it only __as example__. Probably other command will cause the same Perl/IPC behavior. Any ideas why?

And yeah , with Capture::Tiny sshutle does not hang ...

Comment on Re^4: Capture::Tiny alternative

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Re^5: Capture::Tiny alternative by thanos1983 (Parson) on Mar 24, 2017 at 15:07 UTC
Hello again melezhik , Try your command like this: my $cmd = `/usr/sbin/sshuttle -v -D -r vagrant@127.0.0.1 192.168.0.0/ +24`; [download] Instead of this: `my $cmd = '/usr/sbin/sshuttle -v -D -r vagrant@127.0.0.1 192.168.0.0/ +24';` [download] Read more about it here (How to run a shell script from a Perl program?). Seeking for Perl wisdom...on the process of learning...not there...yet!	[reply] [d/l] [select]
Re^6: Capture::Tiny alternative by haukex (Archbishop) on Mar 24, 2017 at 15:19 UTC
my $cmd = `/usr/sbin/sshuttle ...` Instead of this: `my $cmd = '/usr/sbin/sshuttle ...'` I don't think that'll help, as the OP said they want to stream the output of the command, while backticks wait until the external command has completed. I suspect there's something going on in the IPC interaction between `sshuttle` and `perl` calling it (maybe `sshuttle` isn't daemonizing properly when called from Perl or something), at the moment I don't know more. melezhik: Just a guess, try `my $cmd = 'nohup /usr/sbin/sshuttle ...'` although that may prevent you from capturing its output, not sure if that's what you want or not. But since you're asking `sshuttle` to damonize (`-D`) anyways...	[reply] [d/l] [select]
Re^7: Capture::Tiny alternative by melezhik (Monk) on Mar 24, 2017 at 15:29 UTC
I don't think that'll help, as the OP said they want to stream the output of the command, while backticks wait until the external command has completed. Sure Just a guess, try my $cmd = 'nohup /usr/sbin/sshuttle ...' although that may prevent you from capturing its output, not sure if that's what you want or not. Unfortunately in real program $cmd comes as users input parameter which I can't alter or modify I suspect there's something going on in the IPC interaction between sshuttle and perl calling it Yeah, this what I tried to say at the very beginning. There are some rare cases ( rare external commands to interact with ) where Perl/IPC/open ( $cmd \|) "hangs" ...	[reply]
Re^6: Capture::Tiny alternative by melezhik (Monk) on Mar 24, 2017 at 15:33 UTC
Anyway, Capture::Tiny::Extended looks like good for me, so I will try ... and let know ...	[reply]
Re^6: Capture::Tiny alternative by melezhik (Monk) on Mar 24, 2017 at 15:21 UTC
yeah, but this way does not work if I want real time STDOUT/STDEER reading ...	[reply]


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