LIMITS.CONF(5) Linux-PAM Manual LIMITS.CONF(5)
limits.conf - configuration file for the pam_limits module
The syntax of the lines is as follows:
<domain> <type> <item> <value>
The fields listed above should be filled as follows:
o a username
o a groupname, with @group syntax. This should not be confused
o the wildcard *, for default entry.
o the wildcard %, for maxlogins limit only, can also be used with
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.
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. .
limits the core file size (KB)
maximum data size (KB)
maximum filesize (KB)
maximum locked-in-memory address space (KB)
maximum number of open files
maximum resident set size (KB)
maximum stack size (KB)
maximum CPU time (minutes)
maximum number of processes
address space limit (KB)
maximum number of logins for this user except for this with
maximum number of logins on system
the priority to run user process with (negative values boost
maximum locked files (Linux 2.4 and higher)
maximum number of pending signals (Linux 2.6 and higher)
maximum memory used by POSIX message queues (bytes) (Linux 2.6
maximum nice priority allowed to raise to (Linux 2.6.12 and
higher) values: [-20,19]
maximum realtime priority allowed for non-privileged processes
(Linux 2.6.12 and higher)
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
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).
These are some example lines which might be specified in
* 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
pam_limits(8), pam.d(5), pam(7)
pam_limits was initially written by Cristian Gafton <gaftonATredhat.com>
Linux-PAM Manual 07/27/2008 LIMITS.CONF(5)