User Commands limit(1)
NAME
limit, ulimit, unlimit - set or get limitations on the sys-
tem resources available to the current shell and its descen-
dentsSYNOPSIS
/usr/bin/ulimit [-f] [blocks]
shulimit [- [HS] [a | cdfnstv]]
ulimit [- [HS] [c | d | f | n | s | t | v]] limit
cshlimit [-h] [resource [limit]]
unlimit [-h] [resource]
kshulimit [-HSacdfnstv] [limit]
ksh93ulimit [-HSacdfmnpstv] [limit]
DESCRIPTION
/usr/bin/ulimit
The ulimit utility sets or reports the file-size writing
limit imposed on files written by the shell and its child processes (files of any size can be read). Only a process with appropriate privileges can increase the limit. shThe Bourne shell built-in function, ulimit, prints or sets
hard or soft resource limits. These limits are described in getrlimit(2).If limit is not present, ulimit prints the specified limits.
Any number of limits can be printed at one time. The -a
option prints all limits.If limit is present, ulimit sets the specified limit
tolimit. The string unlimited requests that the current limit, if any, be removed. Any user can set a soft limit toSunOS 5.11 Last change: 16 Apr 2010 1
User Commands limit(1) any value less than or equal to the hard limit. Any user can lower a hard limit. Only a user with appropriate privileges can raise or remove a hard limit. See getrlimit(2).The -H option specifies a hard limit. The -S option speci-
fies a soft limit. If neither option is specified, ulimit
sets both limits and prints the soft limit. The following options specify the resource whose limits are to be printed or set. If no option is specified, the file size limit is printed or set.-c Maximum core file size (in 512-byte blocks)
-d Maximum size of data segment or heap (in Kbytes)
-f Maximum file size (in 512-byte blocks)
-n Maximum file descriptor plus 1
-s Maximum size of stack segment (in Kbytes)
-t Maximum CPU time (in seconds)
-v Maximum size of virtual memory (in Kbytes)
cshThe C-shell built-in function, limit, limits the consumption
by the current process or any process it spawns, each not to exceed limit on the specified resource. The string unlimited requests that the current limit, if any, be removed. If limit is omitted, prints the current limit. If resource is omitted, displays all limits.-h Use hard limits instead of the current limits. Hard
limits impose a ceiling on the values of the current limits. Only the privileged user can raise the hard limits. resource is one of:SunOS 5.11 Last change: 16 Apr 2010 2
User Commands limit(1) cputime Maximum CPU seconds per process. filesize Largest single file allowed. Limited to the size of the filesystem and capabilities of the filesystem. See df(1M). datasize The maximum size of a process's heap in kilobytes. stacksize Maximum stack size for the process. The default stack size is 2^64. coredumpsize Maximum size of a core dump (file). This is limited to the size of the filesystem. descriptors Maximum number of file descriptors. Run the sysdef(1M) command to obtain the maximum possible limits for your system. The values reported by sysdef are in hexadecimal, but can be translated into decimal numbers using the bc(1) command. memorysize Maximum size of virtual memory.limit is a number, with an optional scaling factor, as fol-
lows: nh Hours (for cputime).nk n kilobytes. This is the default for all but cpu-
time. nm n megabytes or minutes (for cputime). mm:ss Minutes and seconds (for cputime). unlimit removes a limitation on resource. If no resource is specified, then all resource limitations are removed. See the description of the limit command for the list ofSunOS 5.11 Last change: 16 Apr 2010 3
User Commands limit(1) resource names.-h Remove corresponding hard limits. Only the privileged
user can do this. kshThe Korn shell built-in function, ulimit, sets or displays a
resource limit. The available resources limits are listedbelow. Many systems do not contain one or more of these lim-
its. The limit for a specified resource is set when limit is specified. The value of limit can be a number in the unit specified below with each resource, or the value unlimited. The string unlimited requests that the current limit, ifany, be removed. The -H and -S flags specify whether the
hard limit or the soft limit for the specified resource is set. A hard limit cannot be increased once it is set. A soft limit can be increased up to the value of the hard limit. Ifneither the -H or -S options is specified, the limit applies
to both. The current resource limit is printed when limit isomitted. In this case, the soft limit is printed unless -H
is specified. When more than one resource is specified, then the limit name and unit is printed before the value.-a Lists all of the current resource limits.
-c The number of 512-byte blocks on the size of core
dumps.-d The number of K-bytes on the size of the data area.
-f The number of 512-byte blocks on files written by
child processes (files of any size can be read).-n The number of file descriptors plus 1.
-s The number of K-bytes on the size of the stack area.
-t The number of seconds (CPU time) to be used by each
process.-v The number of K-bytes for virtual memory.
SunOS 5.11 Last change: 16 Apr 2010 4
User Commands limit(1)If no option is specified, -f is assumed.
Per-Shell Memory Parameters
The heapsize, datasize, and stacksize parameters are notsystem tunables. The only controls for these are hard lim-
its, set in a shell startup file, or system-wide soft lim-
its, which, for the current version of the Solaris OS, is 2^64bytes. ksh93ulimit sets or displays resource limits. These limits apply
to the current process and to each child process createdafter the resource limit has been set. If limit is speci-
fied, the resource limit is set, otherwise, its current value is displayed on standard output. Increasing the limit for a resource usually requires special privileges. Some systems allow you to lower resource limits and later increase them. These are called soft limits. Once a hard limit is set the resource cannot be increased. Different systems allow you to specify different resources and some restrict how much you can raise the limit of the resource. The value of limit depends on the unit of the resourcelisted for each resource. In addition, limit can be "unlim-
ited" to indicate no limit for that resource.If you do not specify -H or -S, -S is used for listing and
both -S and -H are used for setting resources.
If you do not specify any resource, the default is -f.
The following options are available for ulimit in ksh93:
-a Displays all current resource limits.
-b Specifies the socket buffer size in bytes.
--sbsize
-c Specifies the core file size in blocks.
--core
SunOS 5.11 Last change: 16 Apr 2010 5
User Commands limit(1)-d Specifies the data size in kbytes.
--data
-f Specifies the file size in blocks.
--fsize
-H Displays or sets a hard limit.
-L Specifies the number of file locks.
--locks
-l Specifies the locked address space in Kbytes.
--memlock
-M Specifies the address space limit in Kbytes.
--as
-n Specifies the number of open files.
--nofile
-p Specifies the pipe buffer size in bytes.
--pipe
-m Specifies the resident set size in Kbytes
--rss
-S Displays or sets a soft limit.
-s Specifies the stack size in Kbytes.
--stack
-T Specifies the number of threads.
--threads
-t Specifies the CPU time in seconds.
--cpu
-u Specifies the number of processes.
--nproc
-v Specifies the process size in Kbytes.
--vmem
OPTIONSThe following option is supported by /usr/bin/ulimit:
-f Sets (or reports, if no blocks operand is present),
the file size limit in blocks. The -f option is also
the default case.SunOS 5.11 Last change: 16 Apr 2010 6
User Commands limit(1) OPERANDSThe following operand is supported by /usr/bin/ulimit:
blocks The number of 512-byte blocks to use as the new
file size limit.EXAMPLES
/usr/bin/ulimit
Example 1 Limiting the Stack SizeThe following example limits the stack size to 512 kilo-
bytes:example% ulimit -s 512
example% ulimit -a
time(seconds) unlimited file(blocks) 100 data(kbytes) 523256 stack(kbytes) 512 coredump(blocks) 200 nofiles(descriptors) 64 memory(kbytes) unlimited sh/ksh Example 2 Limiting the Number of File Descriptors The following command limits the number of file descriptors to 12:example$ ulimit -n 12
example$ ulimit -a
time(seconds) unlimited file(blocks) 41943 data(kbytes) 523256 stack(kbytes) 8192 coredump(blocks) 200 nofiles(descriptors) 12 vmemory(kbytes) unlimited csh Example 3 Limiting the Core Dump File SizeSunOS 5.11 Last change: 16 Apr 2010 7
User Commands limit(1) The following command limits the size of a core dump file size to 0 kilobytes:example% limit coredumpsize 0
example% limit
cputime unlimited filesize unlimited datasize 523256 kbytes stacksize 8192 kbytes coredumpsize 0 kbytes descriptors 64 memorysize unlimited Example 4 Removing the limitation for core file size The following command removes the above limitation for the core file size:example% unlimit coredumpsize
example% limit
cputime unlimited filesize unlimited datasize 523256 kbytes stacksize 8192 kbytes coredumpsize unlimited descriptors 64 memorysize unlimited ENVIRONMENT VARIABLES See environ(5) for descriptions of the following environmentvariables that affect the execution of ulimit: LANG, LC_ALL,
LC_CTYPE, LC_MESSAGES, and NLSPATH.
EXIT STATUSThe following exit values are returned by ulimit:
0 Successful completion. >0 A request for a higher limit was rejected or an error occurred.ATTRIBUTES
SunOS 5.11 Last change: 16 Apr 2010 8
User Commands limit(1)See attributes(5) for descriptions of the following attri-
butes:/usr/bin/ulimit, csh, ksh, sh
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcs ||_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
ksh93____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcsu ||_____________________________|_____________________________|
| Interface Stability | Uncommitted ||_____________________________|_____________________________|
SEE ALSO
bc(1), csh(1), ksh(1), ksh93(1), sh(1), df(1M), su(1M), swap(1M), sysdef(1M), getrlimit(2), attributes(5), environ(5), standards(5)SunOS 5.11 Last change: 16 Apr 2010 9