Mail::Audit, sendmail, and Sys::Hostname: hostname fails in .forward

FoxtrotUniform has asked for the wisdom of the Perl Monks concerning the following question:

Monks,

I'm trying to write a mail filter using the excellent Mail::Audit module with sendmail 8.11.6, but when the script is run by the mailer (through a .forward file), Sys::Hostname throws errors:

   ----- The following addresses had permanent fatal errors -----
|/home/matt/devel/bin/mail_filter
    (reason: 1)
    (expanded from: <matt@infernus.net>)

   ----- Transcript of session follows -----
Use of uninitialized value at /usr/libdata/perl/5.00503/Sys/Hostname.p
+m line 100.
Use of uninitialized value at /usr/libdata/perl/5.00503/Sys/Hostname.p
+m line 109.
Can't exec "/com/host": No such file or directory at
/usr/libdata/perl/5.00503/Sys/Hostname.pm line 115.
Cannot get host name of local machine at
/usr/local/lib/perl5/site_perl/5.005/Mail/Audit.pm line 17
BEGIN failed--compilation aborted at /home/matt/devel/bin/mail_filter 
+line 7.
554 5.3.0 unknown mailer error 1
[download]

However, when I run ~/devel/bin/mail_filter by hand, it has no problems whatsoever, and neither does Sys::Hostname:

matt@shub-niggurath:~
Thu Jun 20-14:10:28>perl -MSys::Hostname -e 'print hostname, "\n"'
shub-niggurath.infernus.net
matt@shub-niggurath:~
Thu Jun 20-14:18:00>
[download]

I thought that it might be an environment issue... but my mail_filter script is chmod 744: only I can execute it! Since it's obviously being executed by me, it should have the standard paths, and be able to find /bin/hostname... right?

I can't find any indication of this happening to other Mail::Audit users, nor any mention of similar Sys::Hostname bugs. The local documentation of sendmail's .forward files isn't especially helpful: it says what they do, but not how. Help?

-- The hell with paco, vote for Erudil! :wq

Comment on Mail::Audit, sendmail, and Sys::Hostname: hostname fails in .forward Select or Download Code

Replies are listed 'Best First'.
Re: Mail::Audit, sendmail, and Sys::Hostname: hostname fails in .forward by robobunny (Friar) on Jun 20, 2002 at 20:56 UTC
you can't really trust your path when running something that isn't an interactive shell. things like that typically don't read your /etc/profile, .profile, .bashrc, etc, so you are stuck with a default path the system gives you. of course, that should have /bin in it. you can always set your path at the beginning of your script: `$ENV{'PATH'} = "/bin:/usr/bin";` [download] it's a little surprising that it actually got that far, i would expect it to get the hostname long before it resorts to running external commands, from POSIX::uname or one of the other methods it employs.	[reply] [d/l]
Re(2): Mail::Audit, sendmail, and Sys::Hostname: hostname fails in .forward by FoxtrotUniform (Prior) on Jun 20, 2002 at 21:02 UTC
Tried setting the path in a BEGIN block, no change whatsoever in the script's behaviour. :-( `-- The hell with paco, vote for Erudil! :wq`	[reply]
Re: Mail::Audit, sendmail, and Sys::Hostname: hostname fails in .forward by robobunny (Friar) on Jun 20, 2002 at 21:12 UTC
try testing POSIX::uname to see if it works `use POSIX; $host = (POSIX::uname())[1]; print "$host\n";` [download] it should try to use POSIX::uname after it tries the hostname command, but before it tries uname and /com/host commands. if that works, and you aren't too concerned about portability to non-POSIX systems, you could just use that instead of Sys::Hostname (it's even a standard module, so you don't have anything extra to install).	[reply] [d/l]
Re(2): Mail::Audit, sendmail, and Sys::Hostname: hostname fails in .forward by FoxtrotUniform (Prior) on Jun 20, 2002 at 21:23 UTC
sigh `POSIX::uname` works just fine, as does `hostname` and all the others... EXCEPT when called by Mail::Audit in the `mail_filter` script, and then only when `mail_filter` is run by sendmail from the .forward. (I'm frustrated, but not with you, robobunny; thanks for your help!) `-- The hell with paco, vote for Erudil! :wq`	[reply] [d/l] [select]
Hack -- Success! Re: Mail::Audit, sendmail, and Sys::Hostname: hostname fails in .forward by FoxtrotUniform (Prior) on Jun 20, 2002 at 21:33 UTC
By the simple expedient of creating a bogus `/com/host` script, I've coerced my script into running. (Turns out you can't really do anything with `%ENV` in a .forward jail.) `-- The hell with paco, vote for Erudil! :wq`	[reply] [d/l]