ulimit is a shell command to control the resources available to a bash shell and all the programs that are started from this shell. We can get and set the ulimit of a process or a user
Ulimit of a process
Ulimit of a process can be found by doing cat of /process/<pid>/limits.
root@ip-10-23-56-98:~$ cat /proc/17846/limits Limit Soft Limit Hard Limit Units Max cpu time unlimited unlimited seconds Max file size unlimited unlimited bytes Max data size unlimited unlimited bytes Max stack size 8388608 unlimited bytes Max core file size 0 unlimited bytes Max resident set unlimited unlimited bytes Max processes 4096 4096 processes Max open files 65536 65536 files Max locked memory 65536 65536 bytes Max address space unlimited unlimited bytes Max file locks unlimited unlimited locks Max pending signals 245562 245562 signals Max msgqueue size 819200 819200 bytes Max nice priority 0 0 Max realtime priority 0 0 Max realtime timeout unlimited unlimited us
Ulimit of a User
To find the ulimits for a user just do a cat of `/etc/security/limits.conf` file, this file lists entries for all users.
root@ip-10-23-56-98:~$ cat /etc/security/limits.conf # /etc/security/limits.conf # #Each line describes a limit for a user in the form: # #&lt;domain&gt; &lt;type&gt; &lt;item&gt; &lt;value&gt; # #Where: #&lt;domain&gt; can be: # - a 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, &lt;domain&gt; must be # the literal username root. # #&lt;type&gt; can have the two values: # - "soft" for enforcing the soft limits # - "hard" for enforcing hard limits # #&lt;item&gt; can be one of the following: # - core - limits the core file size (KB) # - data - max data size (KB) # - fsize - maximum filesize (KB) # - memlock - max locked-in-memory address space (KB) # - nofile - max number of open files # - rss - max resident set size (KB) # - stack - max stack size (KB) # - cpu - max CPU time (MIN) # - nproc - max number of processes # - as - address space limit (KB) # - maxlogins - max number of logins for this user # - maxsyslogins - max number of logins on the system # - priority - the priority to run user process with # - locks - max number of file locks the user can hold # - sigpending - max number of pending signals # - msgqueue - max memory used by POSIX message queues (bytes) # - nice - max nice priority allowed to raise to values: [-20, 19] # - rtprio - max realtime priority # - chroot - change root to directory (Debian-specific) # #&lt;domain&gt; &lt;type&gt; &lt;item&gt; &lt;value&gt; # #* soft core 0 #root hard core 100000 #* hard rss 10000 #@student hard nproc 20 #@faculty soft nproc 20 #@faculty hard nproc 50 #ftp hard nproc 0 #ftp - chroot /ftp #@student - maxlogins 4 # End of file