Ulimit Values


Changing ulimit values in AIX
Edit the ulimit value file under /etc/security/limits
The current resource limit is printed when you omit the Limit parameter. The soft limit is printed unless you specify the -H flag. When you specify more than one resource, the limit name and unit is printed before the value. If no option is given, the -f flag is assumed.
Since the ulimit command affects the current shell environment, it is provided as a shell regular built-in command. If this command is called in a separate command execution environment, it does not affect the file size limit of the caller's environment. This would be the case in the following examples:
# nohup ulimit -f 10000
# env ulimit 10000
Once a hard limit has been decreased by a process, it cannot be increased without root privilege, even to revert to the original limit.
Flags
Item Description
-a Lists all of the current resource limits.
-c Specifies the size of core dumps, in number of 512-byte blocks.
-d Specifies the size of the data area, in number of K bytes.
-f Sets the file size limit in blocks when the Limit parameter is used, or reports the file size limit if no parameter is specified. The -f flag is the default.
-H Specifies that the hard limit for the given resource is set. If you have root user authority, you can increase the hard limit. Anyone can decrease it.
-m Specifies the size of physical memory (resident set size), in number of K bytes. This limit is not enforced by the system.
-n Specifies the limit on the number of file descriptors a process may have.
-r Specifies the limit on the number of threads a process can have.
-s Specifies the stack size, in number of K bytes.
-S Specifies that the soft limit for the given resource is set. A soft limit can be increased up to the value of the hard limit. If neither the -H nor -S flags are specified, the limit applies to both.
-t Specifies the number of seconds to be used by each process.
Example
To set the file size limit to 51,200 bytes, enter:
# ulimit -f 100
To list all the current resource limits, enter:
# ulimit -a
time(seconds) unlimited
file(blocks) 2097151
data(kbytes) 131072
stack(kbytes) 32768
memory(kbytes) 65536
coredump(blocks) 2097151
nofiles(descriptors) 2000
threads(per process) unlimited
processes(per user) unlimited
Note : ulimit change takes effect after reboot

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