Sendmail failing quietly

Ran into this issue today. I noticed that we were not receiving some of our emails from our notification/monitoring server (a RHEL box). A quick check through maillog on the host didn't indicate any problems. However, I did observe that it seemed like mail hadn't been sent in a few days - which was not normal.

I tried a test with mailx which resulted in this:

[root@somehost]# mailx -s "testing123" me
testing 1 2 3...
.
Cc:
fprintf.c:50: SM_REQUIRE((fp) != NULL && (fp)->sm_magic == (SmFileMagic)) failed

[root@somehost]#

The issue turned out to be that /var had run out of available inodes due to an application writing thousands of tiny files. This was verified via dumpe2fs output on the Logical Volume. Once the inode issue was corrected mail began flowing normally again.

bash and tab completion of symlinks to directories

When using bash, ever wonder why you have to hit tab twice with completion when the object is a symlink to a directory?
For example:

bash-3.1$ mkdir -p a/b/c/d
bash-3.1$ ln -s a/b/c carrot
bash-3.1$ cd c<tab>arrot<tab>/

It's due to the GNU readline library. Readline has several variables that can be set to influence its behavior, including tab completion of symlinks to directory names. If you find double tapping tab annoying, the fix is trivial. Simply add these two lines to your inputrc:

set mark-directories On
set mark-symlinked-directories On

inputrc will be /etc/inputrc or your ~/.inputrc, either will work.