Question: I saw three copies of a process running and one of them cored in what seems like memory issue. Each individually occupies about 3-4 GB of memory..would a limit account for killing one of them? And if this was the case which one would be killed?

Answer: 
They are per process but can be user dependent, and actually the config calls it *domain specific*.

example, I set following limits so that I could process audio with better latency, and I am a member of the audio group. So it only affects my processes.

```
@audio          -       rtprio          100
@audio          -       nice            -10

```

It also depends on the limit which is being set. *maxlogins, nprocs* are obviously per user. on the other hand *core* is a per process limit.

```
<domain> can be:
#        - an user name
#        - a group name, with @group syntax
#        - the wildcard *, for default entry
#        - the wildcard %, can be also used with %group syntax,
#                 for maxlogin limit
#        - NOTE: group and wildcard limits are not applied to root.
#          To apply a limit to the root user, <domain> must be
#          the literal username root.
#

```
Refering `man 5 limits.conf`

```
The pam_limits.so module applies ulimit limits, nice priority 
and number of simultaneous login sessions limit to user login sessions.

The syntax of the lines is as follows:
<domain><type><item><value>

<domain> = a username, a groupname, the wildcard *, the wildcard %, 
           an uid range, a gid range, a gid specified as %:<gid> 
           applicable to maxlogins limit only

```