ulimit官方描述

Provides control over the resources available to the shell and to processes started by  it,  on  systems that allow such control. The -H and -S options specify that the hard or soft limit is set 

for the given resource. A hard limit cannot be increased once it is set; a soft limit may  be  increased  up  to  the value of the hard limit. If neither -H nor -S is specified, both the soft and 

hard limits are set. The value of limit can be a number in the unit specified for the resource or one of the special values hard, soft,  or  unlimited,  which  stand  for  the  current hard limit, 

the current soft limit, and no limit,  respectively.

If limit is omitted, the current value of the soft limit  of  the  resource  is  printed,  unless  the  -H  option is given.  When more than one resource is specified, the limit name and unit are  

printed before the value.

提供控制 shell的可用资源和shell启动的进程,在系统上允许这样的操作。

-H和-S 选项是hard 或者soft 设置对于给定的资源。

一个hard 限制不能被增加 一旦被设置,  一个soft limit 可以被增加 到hard限制的大小

如果 -H或者-S 都没有被指定,那么soft和hard 限制都被设置。

限制的值可以是一个数字单位 对于hard soft的其中一个,或者是unlimited  代表硬限制

当前的soft 限制,和没有限制, 或者单独的

如果限制被忽略,  软限制的当前的值 被打印,除非 指定-H选项

# End of file

 * 		soft 	nofile 		6553

 * 		hard 	nofile 		7553

* 		soft 	nproc 		65530

* 		hard 	nproc 		65531

zjzc01:/root# ulimit   -H -a

core file size          (blocks, -c) unlimited

data seg size           (kbytes, -d) unlimited

scheduling priority             (-e) 0

file size               (blocks, -f) unlimited

pending signals                 (-i) 7808

max locked memory       (kbytes, -l) 64

max memory size         (kbytes, -m) unlimited

open files                      (-n) 7553

pipe size            (512 bytes, -p) 8

POSIX message queues     (bytes, -q) 819200

real-time priority              (-r) 0

stack size              (kbytes, -s) unlimited

cpu time               (seconds, -t) unlimited

max user processes              (-u) 65531

virtual memory          (kbytes, -v) unlimited

file locks                      (-x) unlimited