274 lines
5.2 KiB
Groff
274 lines
5.2 KiB
Groff
'\" t
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.\" Title: limits
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.\" Author: Luca Berra
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.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
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.\" Date: 03/19/2025
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.\" Manual: File Formats and Configuration Files
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.\" Source: shadow-utils 4.17.4
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.\" Language: English
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.\"
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.TH "LIMITS" "5" "03/19/2025" "shadow\-utils 4\&.17\&.4" "File Formats and Configuration"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.SH "NAME"
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limits \- resource limits definition
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.SH "DESCRIPTION"
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.PP
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The
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\fIlimits\fR
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file (/etc/limits
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by default or LIMITS_FILE defined
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config\&.h) describes the resource limits you wish to impose\&. It should be owned by root and readable by root account only\&.
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.PP
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By default no quota is imposed on \*(Aqroot\*(Aq\&. In fact, there is no way to impose limits via this procedure to root\-equiv accounts (accounts with UID 0)\&.
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.PP
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Each line describes a limit for a user in the form:
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.PP
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\fIuser LIMITS_STRING\fR
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.PP
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or in the form:
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.PP
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\fI@group LIMITS_STRING\fR
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.PP
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The
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\fILIMITS_STRING\fR
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is a string of a concatenated list of resource limits\&. Each limit consists of a letter identifier followed by a numerical limit\&.
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.PP
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The valid identifiers are:
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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A: max address space (KB)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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C: max core file size (KB)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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D: max data size (KB)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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F: maximum file size (KB)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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K: file creation mask, set by
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\fBumask\fR(2)\&.
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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I: max nice value (0\&.\&.39 which translates to 20\&.\&.\-19)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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L: max number of logins for this user
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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M: max locked\-in\-memory address space (KB)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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N: max number of open files
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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O: max real time priority
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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P: process priority, set by
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\fBsetpriority\fR(2)\&.
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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R: max resident set size (KB)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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S: max stack size (KB)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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T: max CPU time (MIN)
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.RE
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.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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U: max number of processes
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.RE
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.PP
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For example,
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\fIL2D2048N5\fR
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is a valid
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\fILIMITS_STRING\fR\&. For reading convenience, the following entries are equivalent:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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username L2D2048N5
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username L2 D2048 N5
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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Be aware that after
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\fIusername\fR
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the rest of the line is considered a limit string, thus comments are not allowed\&. An invalid limits string will be rejected (not considered) by the
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\fBlogin\fR
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program\&.
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.PP
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The default entry is denoted by username "\fI*\fR"\&. If you have multiple
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\fIdefault\fR
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entries in your
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\fILIMITS_FILE\fR, then the last one will be used as the default entry\&.
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.PP
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The limits specified in the form "\fI@group\fR" apply to the members of the specified
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\fIgroup\fR\&.
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.PP
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If more than one line with limits for a user exist, only the first line for this user will be considered\&.
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.PP
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If no lines are specified for a user, the last
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\fI@group\fR
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line matching a group whose the user is a member of will be considered, or the last line with default limits if no groups contain the user\&.
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.PP
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To completely disable limits for a user, a single dash "\fI\-\fR" will do\&.
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.PP
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To disable a limit for a user, a single dash "\fI\-\fR" can be used instead of the numerical value for this limit\&.
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.PP
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Also, please note that all limit settings are set PER LOGIN\&. They are not global, nor are they permanent\&. Perhaps global limits will come, but for now this will have to do ;)
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.SH "FILES"
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.PP
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/etc/limits
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.RS 4
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.RE
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.SH "SEE ALSO"
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.PP
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\fBlogin\fR(1),
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\fBsetpriority\fR(2),
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\fBsetrlimit\fR(2)\&.
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