ulimit(1) — Commands
NAME
ulimit − Sets or reports a resource limit
SYNOPSIS
ulimit [−HSacdfmnstvw] [limit]
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
ulimit: XPG4, XPG4−UNIX
Refer to the standards(5) reference page for more information about industry standards and associated tags.
FLAGS
-H[Digital] The limits specified for the resources are hard limits. A hard limit cannot be increased once it is set.
-S[Digital] The limits specified for the resources are soft limits. A soft limit can be increased up to the value of the hard limit.
−a[Digital] Lists all of the current resource limits. The limit parameter is not permitted with this flag.
−c limit[Digital] The limit parameter specifies the number of 512-byte blocks for core dumps.
−d limit[Digital] The limit parameter specifies the number of Kilobytes for the data area.
−f limitThe limit parameter specifies the number of 512-byte blocks for files written by child processes (files of any size can be read).
−m limit
[Digital] The limit parameter specifies the number of Kilobytes for the size of physical memory.
−n limit[Digital] The limit parameter specifies the number of file descriptors.
−s limit[Digital] The limit parameter specifies the number of Kilobytes for the stack area.
−t limit[Digital] The limit parameter specifies the number of seconds to be used by each process.
−v limit[Digital] The limit parameter specifies the number of Kilobytes for virtual memory. This option is supported only if RLIMIT_VMEM has been defined in /usr/include/sys/resource.h at compile-time.
−w limit
[Digital] The limit parameter specifies the number of Kilobytes for the swap area. This option is supported only if RLIMIT_SWAP has been defined in /usr/include/sys/resource.h at compile-time.
PARAMETERS
limitIf no flags are specified, this is the number of 512 byte blocks to use as the new limit to file size. Otherwise, it is the limit applied to the resource indicatd by the flag.
[Digital] This parameter is not allowed with the -a flag.
If this parameter is omitted, the current limit for the indicated resource is reported.
DESCRIPTION
This command sets, or reports, the limit on the size of system resources, as indicated by the flag.
[Digital] If neither the -H flag nor the -S flag is specified, the limit applies to both hard and soft limits. If only the -a flag is specified, soft limits are reported.
If there is no limit on a resource, the limit is reported as unlimited.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of ulimit:
LANGProvides a default value for the internationalization variables that are unset or null. If LANG is unset or null, the corresponding value from the default locale is used. If any of the internationalization variables contain an invalid setting, the utility behaves as if none of the variables had been defined.
LC_ALLIf set to a non-empty string value, overrides the values of all the other internationalization variables.
LC_CTYPEDetermines the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multibyte characters in arguments).
LC_MESSAGESDetermines the locale for the format and contents of diagnostic messages written to standard error.
NLSPATHDetermines the location of message catalogues for the processing of LC_MESSAGES.
NOTES
The ulimit command affects only the current execution environment, therefore it has no effect when run in a separate execution environment such as one of the following:
nohup ulimit -f 10000
env ulimit 10000
RESTRICTIONS
Once a limit has been decreased, only a user with superuser privileges may increase it, even back to its original value.
EXAMPLES
1.To set the file size limit to 51,200 bytes, enter:
ulimit -f 100
2.To report the current file size limit, enter:
ulimit
3.The following example displays all current resource limits:
% ulimit -a
time(seconds) unlimited
file(blocks) unlimited
data(kbytes) 131072
stack(kbytes) 2048
memory(kbytes) 84280
coredump(blocks) unlimited
nofiles(descriptors) 4096
vmemory(kbytes) 1048576
EXIT VALUES
The following exit values are returned:
0Successful completion
>0A request for a higher limit was rejected or an error occurred