Presque ça !

Bonjour,

SNMPDOPTS='-Ls 3 -Lf /dev/null -u snmp -I -smux -p /var/run/snmpd.pid'

Mauvaise option ... à une majuscule près !

SNMPDOPTS='-LS 3 d -Lf /dev/null -u snmp -I -smux -p var/run/snmpd.pid'

Extrait du man de snmpcmd:

LOGGING OPTIONS
The mechanism and destination to use for logging of warning and error messages can be controlled by passing various parameters to the -L flag.
[...]
-Ls FACILITY
Log messages via syslog, using the specified facility ('d' for LOG_DAEMON, 'u' for LOG_USER, or '0'-'7' for LOG_LOCAL0 through LOG_LOCAL7).

There are also "upper case" versions of each of these options, which allow the corresponding logging mechanism to be restricted to certain priorities of message. Using standard error logging as an example:

-LE pri
will log messages of priority 'pri' and above to standard error.

-LE p1-p2
will log messages with priority between 'p1' and 'p2' (inclusive) to standard error.

For -LF and -LS the priority specification comes before the file or facility token. The priorities recognised are:

0 or ! for LOG_EMERG,
1 or a for LOG_ALERT,
2 or c for LOG_CRIT,
3 or e for LOG_ERR,
4 or w for LOG_WARNING,
5 or n for LOG_NOTICE,
6 or i for LOG_INFO, and
7 or d for LOG_DEBUG.

Normal output is (or will be!) logged at a priority level of LOG_NOTICE

Et le snmpd --help:

-L toggle options controlling where to log to
e: log to standard error
o: log to standard output
n: don't log at all
f file: log to the specified file
s facility: log to syslog (via the specified facility)

(variants)
[EON] pri: log to standard error, output or /dev/null for level 'pri' and above
[EON] p1-p2: log to standard error, output or /dev/null for levels 'p1' to 'p2'
[FS] pri token: log to file/syslog for level 'pri' and above
[FS] p1-p2 token: log to file/syslog for levels 'p1' to 'p2'

Voila, bonne chance :)

PS: il y a des outils comme logcheck qui simplifient bien la vie pour la lecture des logs ;)