Linux ulimit 命令

ulimit命令用来限制系统用户对 shell 资源的访问，常见用法如下：

[root@localhost ~]$ ulimit -a            # 查看当前所有的资源限制
[root@localhost ~]$ ulimit -u 65535      # 限制用户能打开的最大进程数
[root@localhost ~]$ ulimit -SHn 65535    # 限制同一时间最多可打开的文件数

命令参数：

-a     All current limits are reported
-b     The maximum socket buffer size
-c     The maximum size of core files created
-d     The maximum size of a process's data segment
-e     The maximum scheduling priority ("nice")
-f     The maximum size of files written by the shell and its children
-i     The maximum number of pending signals
-l     The maximum size that may be locked into memory
-m     The maximum resident set size (many systems do not honor this limit)
-n     The maximum number of open file descriptors (most systems do not allow this value to be set)
-p     The pipe size in 512-byte blocks (this may not be set)
-q     The maximum number of bytes in POSIX message queues
-r     The maximum real-time scheduling priority
-s     The maximum stack size
-t     The maximum amount of cpu time in seconds
-u     The maximum number of processes available to a single user
-v     The maximum amount of virtual memory available to the shell and, on some systems, to its children
-x     The maximum number of file locks
-T     The maximum number of threads
-S     Set a soft limit for the given resource
-H     Set a hard limit for the given resource

命令输出：

[root@localhost ~]$ ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 257403
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 65535
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 10240
cpu time               (seconds, -t) unlimited
max user processes              (-u) 65535
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

线上的用法：

ulimit -u 65535
ulimit -SHn 65535
sed -i '/ulimit/d' /etc/rc.d/rc.local
echo "ulimit -u 65535" >> /etc/rc.d/rc.local
echo "ulimit -SHn 65535" >> /etc/rc.d/rc.local