ulimit

The ulimit command sets or reports user process resource limits. The default limits are defined and applied when a new user is added to the system. Limits are categorized as either soft or hard. With the ulimit command, you can change your soft limits for the current shell environment, up to the maximum set by the hard limits. You must have root user authority to change resource hard limits.

The user process resource limits exist in the file /etc/security/limits.conf file.

For my infauser account, the output of the ulimit -a command looks like this:

core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 31113
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 32000
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

core file size

The max core file size is 0. Yes, that means nothing, no data, no core dump. If a process that you are running aborts, no core file is going to be dropped into your home directory. As long as the core file size is set to zero, core dumps are not allowed. This makes sense for most users since they probably wouldn't do anything more with a core dump other than erase it, but if you need a core dump to debug problems you are running into with an application, you might want to set your core file size to unlimited -- and maybe you can.

max user processes

Limits the number of processes that an individual can run. The ulimit option used for this is -u. You can look at your limit as we did above with the ulimit -a command or show just the "nproc" limit with the command ulimit -u.