DESCRIPTION
       Warning:  This  routine is obsolete. The include file is no longer provided by glibc.  Use getrlimit(2),
       setrlimit(2) and sysconf(3) instead.  For the shell command ulimit, see bash(1).
 
       The ulimit call will get or set some limit for the current process.  The cmd argument can  have  one  of
       the following values.
 
       UL_GETFSIZE
              Return the limit on the size of a file, in units of 512 bytes.
 
       UL_SETFSIZE
              Set the limit on the size of a file.
 
       3      (Not implemented for Linux.)  Return the maximum possible address of the data segment.
 
       4      (Implemented  but  no  symbolic  constant provided.)  Return the maximum number of files that the
              calling process can open.
 
RETURN VALUE
       On success, ulimit returns a nonnegative value.  On error, -1 is returned, and errno  is  set  appropri?
       ately.
 
ERRORS
       EPERM  A non-root process tried to increase a limit.
 
CONFORMING TO
       SVID.

# /etc/security/limits.conf
#
#Each line describes a limit for a user in the form:
#
#<domain>        <type>  <item>  <value>
#
#Where:
#<domain> can be:
#        - an user name
#        - a group name, with @group syntax
#        - the wildcard *, for default entry
#
#<type> can have the two values:
#        - "soft" for enforcing the soft limits
#        - "hard" for enforcing hard limits
#
#<item> 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
#        - maxlogins - max number of logins for this user
#        - priority - the priority to run user process with
#
#<domain>      <type>  <item>         <value>
#
 
#*               soft    core            0
#*               hard    rss             10000
#@student        hard    nproc           20
#@faculty        soft    nproc           20
#@faculty        hard    nproc           50
#ftp             hard    nproc           0
#@student        -       maxlogins       4
 
# End of file

cat /proc/sys/fs/file-max
209708

cat /etc/sysctl.conf
#
# /etc/sysctl.conf - Configuration file for setting system variables
# See sysctl.conf (5) for information.
#
#kernel.domainname = example.com
#net/ipv4/icmp_echo_ignore_broadcasts=1