LIMITS.CONF(5)

NAME
limits.conf - configuration file for the pam_limits module

DESCRIPTION

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-existing 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)

    stack
        maximum stack size (KB)

    cpu
        maximum CPU time (minutes)

    nproc
        maximum number of processes

    as
        address space limit (KB)

    maxlogins
        maximum number of logins for this user except for this with uid=0

    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) values: [-20,19]

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

    chroot
        the directory to chroot the user to

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

SEE ALSO

pam_limits(8), pam.d(5), pam(7)

AUTHOR

pam_limits was initially written by Cristian Gafton <gafton@redhat.com>