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why is return always 0? jammer 03-16-2008
Posted by jammer on March 16, 2008, 8:45 pm
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 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";
}

Posted by sandy_saydakov on March 16, 2008, 9:10 pm
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> 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/

Posted by jammer on March 17, 2008, 3:56 pm
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On Mar 16, 9:10 pm, sandy_sayda...@yahoo.com wrote:
>
> > 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.
>
> -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. :-(

Posted by sandy_saydakov on March 17, 2008, 4:49 pm
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> > Make sure the binary returns non-zero on failure. Try that command on
> > the command line and do "echo $?" right after.
>
> 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/

Posted by hymie! on March 18, 2008, 9:12 am
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In our last episode, the evil Dr. Lacto had captured our hero,
sandy_saydakov@yahoo.com, who said:
>> > Make sure the binary returns non-zero on failure. Try that command on
>> > the command line and do "echo $?" right after.
>>
>> 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.

The fact that the host does not exist does not necessarily mean that
the tftp program failed, thus the 0 exit code.

eric-x% nslookup fuzzy
Server: 205.196.81.2
Address: 205.196.81.2#53

** server can't find fuzzy: NXDOMAIN

eric-x% echo $?
0
eric-x% finger hymie
finger: hymie: no such user.
eric-x% echo $?
0
eric-x%


--hymie! http://lactose.homelinux.net/~hymie hymie@lactose.homelinux.net
------------------------ Without caffeine for 504 days ------------------------

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