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 with netgroups.
o the wildcard *, for default entry.
o 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.
hardfor 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.
softfor 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. .
corelimits the core file size (KB)
datamaximum data size (KB)
fsizemaximum filesize (KB)
memlockmaximum locked-in-memory address space (KB)
nofilemaximum number of open files
rssmaximum resident set size (KB) (Ignored in Linux 2.4.30 and higher)
stackmaximum stack size (KB)
cpumaximum CPU time (minutes)
nprocmaximum number of processes
asaddress space limit (KB)
maxloginsmaximum number of logins for this user except for this with uid=0
maxsysloginsmaximum number of logins on system
prioritythe priority to run user process with (negative values boost process priority)
locksmaximum locked files (Linux 2.4 and higher)
sigpendingmaximum number of pending signals (Linux 2.6 and higher)
msqqueuemaximum memory used by POSIX message queues (bytes) (Linux 2.6 and higher)
nicemaximum nice priority allowed to raise to (Linux 2.6.12 and higher) values: [-20,19]
rtpriomaximum realtime priority allowed for non-privileged processes (Linux 2.6.12 and higher)
chrootthe 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).
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
pam_limits(8), pam.d(5), pam(7), getrlimit(2) getrlimit(3p)
pam_limits was initially written by Cristian Gafton <email@example.com>
|Linux-PAM Manual||LIMITS.CONF (5)||05/31/2011|