On 6/20/2013 10:00 PM, Bob Miller wrote:
Hi Ben,
Maybe using something like set -e to try and get some output from the script?
Adding the -e switch doesn't seem to produce any output, either.
To be clear, I meant putting the line:
set -e
near the top of your script. I forget exactly how it functions, but it makes it so when a script fails it spits out a why on stdout (or maybe stderr). I believe the -x argument does something useful for troubleshooting too, but it's been too long.
man bashknows all...
Oops! Now I understand what you meant. I tried adding "set -e" at the top of my shell script, but it doesn't shed much light on the problem.
A quick Google search reveals that "set -e causes the shell to exit if any subcommand or pipeline returns a non-zero status." The result is predictable: the call to "deliver" exits with status 75, so using "set -e" causes the script as a whole to return a non-zero exit status, which in turn causes Dovecot to throw an error in my IMAP client: "[SERVERBUG] failed to send mail".
It really boils-down to the fact that I can call the following on the command-line and it functions as expected:
su vmail -c '/usr/lib/dovecot/deliver -a "sa-training@example.com" -d "sa-training@example.com" -m "Training.SPAM" -p "/tmp/sendmail-msg-25794.txt"'
Yet, when I attempt to do the exact same thing from within the pipe script that Dovecot Antispam calls, I receive exit code 75 from deliver/dovecot-lda and absolutely nothing is logged, with exception of the information of which I'm already aware (logged to syslog).
I am echo-ing $(whoami) just before calling "deliver" within the pipe script and the output is "vmail". So, it's not as though the vmail user somehow lacks the permissions required to send via dovecot-lda.
There are two things that came to mind when I read your mail yesterday. They are the first things I check for when my commands work and my scripts don't.
The first is $PATH, I have found innumerable times when a script wouldn't run it was because it wasn't running with a fully loaded $PATH variable, and this is especially true if you are launching your script from cron. To work around this I either put a PATH= at the top of the script, or I run the script as an argument to bash instead of using the executable bit (ie
bash /path/to/script.shinstead of./script.sh) so the path is retained from the shell. I decided against mentioning this yesterday because I noted you only used full paths in your script, which should also work to avoid this problem.
All excellent insights.
You can see the PATH value in my previous message on this subject (from a few minutes ago); it matches the value that I see as "root" when I print the PATH within the shell. So, that seems okay.
Also, I took your good advice and eliminated the potential for the vmail user's shell choice (which happens to be /bin/sh, *not* /bin/bash) to affect the script's behavior. To do this I modified my antispam configuration directives as such:
antispam_pipe_program = /bin/bash antispam_pipe_program_args = /usr/bin/sa-learn-pipe.sh antispam_pipe_program_spam_arg = --spam antispam_pipe_program_notspam_arg = --ham
Unfortunately, this change doesn't change the result at all; the call to "deliver" still exits with status code 75.
The other thing I didn't mention was the permissions on the path to /usr/lib/dovecot/deliver (or any other path, really). Directories with no world read/execute can prevent scripts from using files beneath them if they don't have permissions on each directory level in the path. I didn't mention this yesterday because you said you ran the script as vmail. However, looking at your "su vmail -c" command, I remember some times when "su postrgres -c" didn't work when "su - postrgres" then running the command did.
I have tried using "su vmail -c [...]", as well as "su vmail" and then pasting the command into the shell. Both yield the same result.
Also, there's no question that the vmail user is able to execute dovecot-adm; if he weren't, then a) pasting the command into the shell wouldn't work (and this does work), and b) I wouldn't be receiving exit status code 75, which is unique to dovecot-adm (I assume that I'd receive a more generic code, like 1, if it was a permissions problem).
Probably neither of these will be useful to you, but I mention them in hope that they trigger and idea or set you on an investigative path that proves helpful...
Any help at all is useful! I really appreciate the time and thought you put into your posts. I wish I felt closer to a solution... :(
Please do reply if you have any additional thoughts. I'm at my wit's end here!
Thanks again,
-Ben
What is the explanation for this behavior? It has to be something to do with how the plug-in calls the script. Does the plug-in call the script in some other context, like chroot?
As a final point of note, is it just me, or is the "90-plugin.conf" snippet incorrect at the bottom of http://wiki2.dovecot.org/Plugins/Antispam ? Those values appear to be for the analogous Dovecot 1 plug-in, e.g., "antispam_mail_sendmail" is used, when the equivalent directive is called "antispam_pipe_program" in versions >= 2.0.
-Ben