Configure-time ps command truncates command names

[Gerald Combs]

It looks like the nagios-plugins package is configured with

  --with-ps-command="/bin/ps axwwo 'stat uid pid ppid vsz rss pcpu etime comm args'"

Unfortunately using "comm" returns truncated command names (via /proc/[pid]/status) which makes it difficult or impossible to use check_procs -C. For example, "check_procs -C apache2" fails while "check_procs -C apach" works.

[Jan Wagner (waja)]

sorry ... can't reproduce your problem ... at least on quantal:

root@ubuntu:~# LANG=C /usr/lib/nagios/plugins/check_procs -C getty
PROCS OK: 6 Prozesse with command name 'getty'
root@ubuntu:~# ps aux|grep getty
root 1004 0.0 0.0 4632 844 tty4 Ss+ 20:33 0:00 /sbin/getty -8 38400 tty4
root 1008 0.0 0.0 4632 856 tty5 Ss+ 20:33 0:00 /sbin/getty -8 38400 tty5
root 1023 0.0 0.0 4632 848 tty2 Ss+ 20:33 0:00 /sbin/getty -8 38400 tty2
root 1025 0.0 0.0 4632 856 tty3 Ss+ 20:33 0:00 /sbin/getty -8 38400 tty3
root 1029 0.0 0.0 4632 848 tty6 Ss+ 20:33 0:00 /sbin/getty -8 38400 tty6
root 1492 0.0 0.0 4632 852 tty1 Ss+ 20:33 0:00 /sbin/getty -8 38400 tty1
root 13428 0.0 0.0 5636 816 pts/0 S+ 22:13 0:00 grep getty

looks like you messed your local environment

[Gerald Combs (gerald.combs)]

That's because "/sbin/getty" is shorter than 15 characters, which means that /proc/<pid>/status isn't truncating it.

[Gerald Combs (gerald.combs)]

...and this problem has been reported before: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=513460

[Jan Wagner (waja)]

Am 16.12.12 01:31, schrieb Gerald Combs:
> That's because "/sbin/getty" is shorter than 15 characters, which
> means that /proc/<pid>/status isn't truncating it.

that's true, but this is the same for "apache2" as you reported first:

$ LANG=C /usr/lib/nagios/plugins/check_procs -C apache2
PROCS OK: 7 processes with command name 'apache2'

> ** Bug watch added: Debian Bug tracker #513460
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=513460

okay ... so you know this won't get fixed (from debian side and this
seems likely in ubuntu too). anyways ... it's not a problem in
nagios-plugins but in linux-meta.

[Jan Wagner (waja)]

This is a kernel limitation ...

[Gerald Combs (gerald.combs)]

This is indeed ultimately a kernel limitation, one which will likely never be fixed. Procps should probably be modified to use /proc/<pid>/cmdline instead of the first line of /proc/<pid>/status for command names since this can affect other programs as well as indicated by the Debian bug.

In the mean time, check_procs is broken. Can we work around the problem by configuring nagios-plugins with a ps argument that returns the full command name, e.g. something like

  --with-ps-command="/bin/ps axwwo 'stat uid pid ppid vsz rss pcpu etime command'"

instead of

  --with-ps-command="/bin/ps axwwo 'stat uid pid ppid vsz rss pcpu etime comm args'"

?

[Holger Weiß (holger-cis)]

No, "comm" cannot be replaced with "command" without breaking things.

However, the workaround you're suggesting is provided by "check_procs -a" (as this uses the format specifier "args", which is just an alias for "command").