Question

In a perl script invoked by nginix/ FCGI , if I do this ssh user@ip <command>, it works i.e. ti connects to remote machine
However, if I do this expect->spawn(ssh user@ip ), FCGI returns an error on doing a open (That code is pretty generic and I don’t expect bugs in it).If I run the script using expect as a standalone, it works.
That leads me to believe that FCGI perhaps does not allow process to be spawned by expect. Though I am not sure. Googling has not helped so far. Any inputs appreciated

Answer 1

The reason it fails is because Expect.pm tries to dup STDIN and FCGI.pm doesn’t support the operation, next release of FCGI.pm will have a more clear error message than: Not a GLOB reference at /path/to/perl/lib/....

The solution is to avoid using the globals: STDIN, STDOUT, STDERR and %ENV when doing inter-process communication.

my ($stdin, $stdout, $stderr, $env) =
  (IO::Handle->new, IO::Handle->new, IO::Handle->new, {});

my $r = FCGI::Request($stdin, $stdout, $stderr, $env)
  or die "Couldn't create FCGI request: '$!'";

while ($r->Accept >= 0) {
    my $exp = Expect->spawn('ssh', 'user@ip')
        or die "Cannot spawn command: $!\n";
    print $stdout "OK\n";
}