Can't open/chown savefile
Today's column is another troubleshooting tale - a real story from the pits of systems administration. And, although the solution to the particular problem encountered turned out to be trivial, the process of tracking it down involved some interesting turns and insights into little known details about the mail command works on a Unix system.
While the subject of today's troubleshooting tale relates to email, the problem cropped up on a server that is anything but a mail server. In fact, any mail stored on the box is exclusively generated on the box and comprises the output of scripts that are run through cron to assist in monitoring various processes and applications. For this reason, the problem didn't get much notice and persisted for a long period of time before anyone thought to complain.
The problem itself was simple, but annoying. Specifically, anytime users on the problematic server quit the mail command after both reading and deleting messages, they would be faced with the message "mail: Cannot open savefile". Afterwards, their inboxes remained intact; in other words, deleted messages had not been removed. Since most of these users weren't interested in the particular cron job output email after perusing it once, they would remove the entire mail file and then go through the same procedure the next day.
Eventually, someone decided to ask why the mail command was giving them such a hard time and, after verifying the nature of the problem, attention was focussed on the troublesome server.
Checking the Server
The /var/mail/directory on the server looked more or less as anyone would have expected it to look. Each user's mail file was owned by the particular user and the group associated with all of the mail files was "mail".
drwxrwxr-x 2 root mail 512 Mar 18 12:34 :saved -rw-rw---- 1 carolt mail 3929 Mar 18 07:11 carolt -rw-rw---- 1 flyguy mail 1860 Mar 18 10:19 flyguy -rw-rw---- 1 jdoe mail 504 Mar 17 13:05 jdoe -rw-rw---- 1 zippo mail 1336 Mar 18 09:00 zippo
Even so, it was easy to confirm that any of these users encountered the same error any time they tried to delete their mail within the purview of the mail command.
What's Different?
The old trick of comparing a "broken" system with a working system didn't lead to any revelations. Comparing the /var/mail directory with the same directory on another server (exhibiting no such mail problems), it was clear that file permissions weren't the issue. Even the :saved directory appeared to be identically configured.
Checking the Web
As is usually the case with problems of this sort, a small population of sysadmins had encountered the same or similar problems and
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