Linux ulimit command

Linux Command Encyclopedia

The Linux ulimit command is used to control the resources of shell programs.

ulimit is a shell built-in command that can be used to control the resources of programs executed by the shell.

Syntax

ulimit [-aHS][-c <core文件上限>][-d <数据节区大小>][-f <文件大小>][-m <内存大小>][-n <文件数目>][-p <缓冲区大小>][-s <堆叠大小>][-t <CPU时间>][-u <程序数目>][-v <虚拟内存大小>]

Parameters：

• -a Display current resource limit settings.
• -c <core file limit> Set the maximum size of the core file, in blocks.
• -d <data segment size> Set the maximum size of the program data segment, in KB.
• -f <file size> Set the maximum file size the shell can create, in blocks.
• -H Set the hard limit of resources, that is, the limit set by the administrator.
• -m <memory size> Specify the upper limit of usable memory, in KB.
• -n <number of files> Specify the maximum number of files that can be opened at the same time.
• -p <buffer size> Specify the size of the pipe buffer, in units of 512 bytes.
• -s <stack size> Specify the upper limit of the stack, in KB.
• -S Set the soft limit of resources.
• -t <CPU time> Specify the upper limit of CPU usage time, in seconds.
• -u <number of programs> The maximum number of programs a user can open.
• -v <virtual memory size> Specify the upper limit of usable virtual memory, in KB.

Examples

Display system resource settings

[root@example ~]# ulimit -a
core file size     (blocks, -c) 0
data seg size      (kbytes, -d) unlimited
file size        (blocks, -f) unlimited
pending signals         (-i) 1024
max locked memory    (kbytes, -l) 32
max memory size     (kbytes, -m) unlimited
open files           (-n) 1024
pipe size      (512 bytes, -p) 8
POSIX message queues   (bytes, -q) 819200
stack size       (kbytes, -s) 10240
cpu time        (seconds, -t) unlimited
max user processes       (-u) 4096
virtual memory     (kbytes, -v) unlimited
file locks           (-x) unlimited
[root@example ~]# 

Set the upper limit of the number of programs for a single user

[root@example ~]# ulimit -u 500 //设置单一用户程序上限
[root@example ~]# ulimit -a
core file size     (blocks, -c) 0
data seg size      (kbytes, -d) unlimited
file size        (blocks, -f) unlimited
pending signals         (-i) 1024
max locked memory    (kbytes, -l) 32
max memory size     (kbytes, -m) unlimited
open files           (-n) 1024
pipe size      (512 bytes, -p) 8
POSIX message queues   (bytes, -q) 819200
stack size       (kbytes, -s) 10240
cpu time        (seconds, -t) unlimited
max user processes       (-u) 500
virtual memory     (kbytes, -v) unlimited
file locks           (-x) unlimited
[root@example ~]# 

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