why is return always 0?

[jammer]

How do I make tftp fail if the host is bad?

my $rc = system( "/usr/bin/tftp bad$host < $tempFile 2>&1 >/
dev/null" );
if ( $rc != 0 ) {
print "unable to tftp to '$host'\n";
exit 1;
} else {
print "success: $rc\n";
}

 

[sandy_saydakov]

How do I make tftp fail if the host is bad?

my $rc = system( "/usr/bin/tftp bad$host < $tempFile 2>&1 >/dev/null" );
if ( $rc != 0 ) {
print "unable to tftp to '$host'\n";
exit 1;
} else {
print "success: $rc\n";
}

Make sure the binary returns non-zero on failure. Try that command on
the command line and do "echo $?" right after.

-sandy
http://myperlquiz.com/

 

[jammer]

Make sure the binary returns non-zero on failure. Try that command on
the command line and do "echo $?" right after.

-sandyhttp://myperlquiz.com/

It prints an error when run interactively.
tftp does run, it just can't find the host.
It returns 0 because it ran, didn't work but it ran. :-(

 

[sandy_saydakov]

It prints an error when run interactively.
tftp does run, it just can't find the host.
It returns 0 because it ran, didn't work but it ran. :-(

So there must be a bug in tftp then. It makes no sense to have a clean
exit code on failure.

For example, try it with 'ls':

ls nonexistent

ls: nonexistent: No such file or directory

echo $?

1
This makes perfect sense, doesn't it?

I would suggest trying a native TFTP Perl module:
http://search.cpan.org/~gsm/TFTP-1.0b3/TFTP.pm

/sandy
http://myperlquiz.com/

 

[xhoster]

It seems that that is a question for the authors of tftp, not
a Perl question. But there may be a Perl work-a-round.

It prints an error when run interactively.

Does it do that when run noninteractively? You could try capturing and
parsing its stderr. IPC::Run might be a good way. (I think it might also
help you trick tftp into thinking it is running interactively, if that is
necessary.)

tftp does run, it just can't find the host.
It returns 0 because it ran, didn't work but it ran. :-(

Well, that was probably a poor design decision. By that criterion, nothing
should ever exit with anything but 0. If it ran, it ran. If it didn't
run, it can't exit with anything at all.

Xho

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[comp.llang.perl.moderated]

How do I make tftp fail if the host is bad?

my $rc = system( "/usr/bin/tftp bad$host < $tempFile 2>&1 >/
dev/null" );
if ( $rc != 0 ) {
print "unable to tftp to '$host'\n";
exit 1;
} else {
print "success: $rc\n";
}

On Solaris anyway, tftp doesn't return an exit code - just writes to
stdout and then prompts.
So you'd have to short-circuit its prompt and
parse the output for specific errors, eg.:

$out = qx { /usr/bin/tftp badhost </dev/null };
if ( $? ) {
die "can't start tftp: $?";
} elsif ($out =~ /unknown host/ ) {
die "failed: $out";
} else {
# ok
...
}

hth,