ulimit -a:
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 127954
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 127954
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

[root@nagapt-100 nagios]# su - nagios
-bash-4.2$ ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 127954
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 4096
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

grep apache /etc/group:
apache:x:48:
nagios:x:993:apache,e31759,nrpe

grep nag /etc/group:
nagios:x:993:apache,e31759,nrpe

ls -l /usr/local/nagios/var:
total 91200
drwxrwxr-x. 2 nagios nagios     4096 Oct  9 00:00 archives
-rwxrwxrwx  1 nagios nagios 25956996 Oct  9 10:22 nagios.log
-rw-r--r--. 1 nagios nagios 14138061 Oct  8 11:15 objects.cache
-rw-------  1 nagios nagios 23174365 Oct  9 10:15 retention.dat
drwxrwsr-x. 2 nagios nagios       41 Oct  8 11:15 rw
drwxr-xr-x. 3 root   root         26 Jul 23 10:50 spool
-rw-rw-r--  1 nagios nagios 23236074 Oct  9 10:22 status.dat

ls -l /usr/local/nagios/var/rw:
total 0
prw-rw---- 1 nagios nagios 0 Oct  8 11:15 nagios.cmd
srw-rw---- 1 nagios nagios 0 Oct  8 11:15 nagios.qh