This bug seems to concern Debian systems only. It can
be fixed by replacing all "ps -axo" with "ps axo" in
the configure file and recompiling the check_procs binary.
$ /usr/lib/netsaint/plugins/check_procs -w 200 -c 400
System call sent warnings to stderr
OK - 121 processes running
The warnings are definetely coming from the ps tool:
$ /bin/ps -axo 'stat uid ppid comm args'
Bad syntax, perhaps a bogus '-'?
....