limits.conf

The syntax of the lines is as follows:

      <domain><type><item><value>

      The fields listed above should be filled as follows:

      <domain>

             ・  a username

             ・  a groupname, with @group syntax. This should not be confused with netgroups.

             ・  the wildcard *, for default entry.

             ・  the wildcard %, for maxlogins limit only, can also be used with %group syntax.

      <type>

             hard   for enforcing hard resource limits. These limits are set by the superuser and enforced by the

                    Kernel. The user cannot raise his requirement of system resources above such values.

             soft   for enforcing soft resource limits. These limits are ones that the user can move up or down

                    within the permitted range by any pre-exisiting hard limits. The values specified with this token

                    can be thought of as default values, for normal system usage.

             -      for enforcing both soft and hard resource limits together.

                    Note, if you specify a type of ’-’ but neglect to supply the item and value fields then the

                    module will never enforce any limits on the specified user/group etc. .

      <item>

             core   limits the core file size (KB)

             data   maximum data size (KB)

             fsize  maximum filesize (KB)

             memlock

                    maximum locked-in-memory address space (KB)

             nofile maximum number of open files

             rss    maximum resident set size (KB) (Ignored in Linux 2.4.30 and higher)

             stack  maximum stack size (KB)

             cpu    maximum CPU time (minutes)

             nproc  maximum number of processes

             as     address space limit

             maxlogins

                    maximum number of logins for this user

             maxsyslogins

                    maximum number of logins on system

             priority

                    the priority to run user process with (negative values boost process priority)

             locks  maximum locked files (Linux 2.4 and higher)

             sigpending

                    maximum number of pending signals (Linux 2.6 and higher)

             msqqueue

                    maximum memory used by POSIX message queues (bytes) (Linux 2.6 and higher)

             nice   maximum nice priority allowed to raise to (Linux 2.6.12 and higher)

             rtprio maximum realtime priority allowed for non-privileged processes (Linux 2.6.12 and higher)

      In general, individual limits have priority over group limits, so if you impose no limits for admin group, but

      one of the members in this group have a limits line, the user will have its limits set according to this line.

      Also, please note that all limit settings are set per login. They are not global, nor are they permanent;

      existing only for the duration of the session.

      In the limits configuration file, the ’#’ character introduces a comment - after which the rest of the line is

      ignored.

      The pam_limits module does its best to report configuration problems found in its configuration file via

      syslog(3).

EXAMPLES

      These are some example lines which might be specified in /etc/security/limits.conf.

      *               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