PATH/tr/basename mystery

myuserid7 has asked for the wisdom of the Perl Monks concerning the following question:

I have a troublesome script which is causing some grief. I've simplified it to a few lines, but the output is confusing me. It seems that tr or basename are being called somewhere without paths.

The script fails on Debian 3.0, but works on Fedora.
Here it is:

#!/usr/bin/perl -w
use strict;

$ENV{'PATH'}=''; # removing this line makes it work

open (MAILQ, "/usr/bin/mailq |")
        or die "open failed: $!\n";
[download]

And here is the error:

/usr/bin/mailq: basename: No such file or directory
/usr/bin/mailq: tr: No such file or directory
[download]

Updated Steve_p - changed pre tags to code tags

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Re: PATH/tr/basename mystery by Roy Johnson (Monsignor) on Apr 14, 2005 at 11:54 UTC
Looks like mailq is a script or includes system calls. Have you taken a look at it? Caution: Contents may have been coded under pressure.	[reply]
Re^2: PATH/tr/basename mystery by myuserid7 (Scribe) on Apr 14, 2005 at 12:01 UTC
You're excellent! I had assumed mailq was a compiled binary. It's a shell script, with paths omitted for the tr and basename commands. Thanks a lot :)	[reply]
Re: PATH/tr/basename mystery by gellyfish (Monsignor) on Apr 14, 2005 at 12:03 UTC
To add a bit to the other replies, where your local MTA is `sendmail` then the `mailq` command is essentially an alias to `sendmail -bp` and so emptying `$PATH` shouldn't cause a problem, however some other MTAs operate differently and only provide the `mailq` command for compatibility with `sendmail` - in these places it is likely that `mailq` is a shell script (as you have seen), your best bet is not to set the `$ENV{PATH}` to '' but to set it to some (relatively) safe valuee such as '/bin:/usr/bin'. Alternatively you could edit the `mailq` script to provide the full path for the commands it can't find. /J\	[reply] [d/l] [select]