有关/etc/security/limits问题的若干说明

时间：2010-05-24 来源：dbconf

AIX 5.3上下面是文件/etc/security/limits文件里面有关软限制和硬限制的部分。 *
* Sizes are in multiples of 512 byte blocks, CPU time is in seconds
*
* fsize      - soft file size in blocks
* core       - soft core file size in blocks
* cpu        - soft per process CPU time limit in seconds
* data       - soft data segment size in blocks
* stack      - soft stack segment size in blocks
* rss        - soft real memory usage in blocks
* nofiles    - soft file descriptor limit
* fsize_hard - hard file size in blocks
* core_hard - hard core file size in blocks
* cpu_hard   - hard per process CPU time limit in seconds
* data_hard - hard data segment size in blocks
* stack_hard - hard stack segment size in blocks
* rss_hard   - hard real memory usage in blocks
* nofiles_hard - hard file descriptor limit
* The following table contains the default hard values if the
* hard values are not explicitly defined:
*
*   Attribute        Value
*   ==========    ============
*   fsize_hard    set to fsize
*   cpu_hard      set to cpu
*   core_hard         -1
*   data_hard         -1
*   stack_hard      8388608
*   rss_hard          -1
*   nofiles_hard      -1
default:
        fsize = -1
        core = 2097151
        cpu = -1
        data = -1
        rss = -1
        stack = -1
        nofiles = 2000 说明： 1.ulimit -Ha 输出硬限制的值 time(seconds)        unlimited
file(blocks)         unlimited
data(kbytes)         unlimited
stack(kbytes)        4194304
memory(kbytes)       unlimited
coredump(blocks)     unlimited
nofiles(descriptors) unlimited
因为在/etc/security/limits没有明确写明对硬限制的设置，所以，取默认的硬限制的值，也就是上面注释文字里面写的那些，stack还是有限制的。 2. ulimit -a 输出软限制的值 time(seconds)        unlimited
file(blocks)         unlimited
data(kbytes)         unlimited
stack(kbytes)        4194304
memory(kbytes)       unlimited
coredump(blocks)     2097151
nofiles(descriptors) 2000
软限制取/etc/security/limits里面default里面的值，虽然里面写的stack没限制，但是由于硬限制已经提前限制了41944304，所以，stack的最大也只能是41944304。 3.如何更改硬限制和软限制的值？ 1）编辑文件/etc/security/limits，直接修改各定义值。此更改在用户退出重新登陆就生效。
2）使用命令ulimit修改默认值。例如：
ulimit -f value
ulimit -c <value>
ulimit -t <value>
ulimit -d <value>
ulimit -s <value>
ulimit -m <value>
ulimit -n <value>
将修改fsize, core, cpu,data, stack, rss和nofiles的soft limit值。
3）使用命令chuser修改某用户的限定值。例如：
chuser fsize=<value> <username>
chuser core=<value> <username
chuser cpu=<value> <username>
chuser data=<value> <username>
chuser limit=<value> <username>
chuser rss=<value> <username>
chuser nofiles=<value> <username>
将用户“username”的soft limits改为值“value”。
chuser hard_fsize=<value> <username>
chuser hard_core=<value> <username>
chuser hard_cpu=<value> <username>
chuser hard_data=<value> <username>
chuser hard_limit=<value> <username>
chuser hard_rss=<value> <username>
chuser hard_nofiles=<value> <username>
将用户“username”的hard limits改为值“value”。 4）smit chuser里面也是可以修改的