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LIMITS.CONF(5) Linux-PAM Manual 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.
 
 
NOTE: group and wildcard limits are not applied to the root user. To set a limit for the root user, this field must contain the literal username root.
<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) (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 (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
All items support the values -1, unlimited or infinity indicating no limit, except for priority and nice.
If a hard limit or soft limit of a resource is set to a valid value, but outside of the supported range of the local system, the system may reject the new limit or unexpected behavior may occur. If the control value required is used, the module will reject the login if a limit could not be set.
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 report configuration problems found in its configuration file and errors via syslog(3).

EXAMPLES

These are some example lines which might be specified in /etc/security/limits.conf.
 
*               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
@student        -       maxlogins       4

SEE ALSO

 
pam_limits(8), pam.d(5), pam(7), getrlimit(2) getrlimit(3p)

AUTHOR

pam_limits was initially written by Cristian Gafton <gafton@redhat.com>
05/31/2011 Linux-PAM Manual