limit(1) User Commands limit(1)NAME
limit, ulimit, unlimit - set or get limitations on the system resources
available to the current shell and its descendents
SYNOPSIS
/usr/bin/ulimit [-f] [blocks]
sh
ulimit [- [HS] [a | cdfnstv]]
ulimit [- [HS] [c | d | f | n | s | t | v]] limit
csh
limit [-h] [resource [limit]]
unlimit [-h] [resource]
ksh
ulimit [-HSacdfnstv] [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 may be read). Only a process with appropriate privileges can
increase the limit.
sh
The 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 may be printed at one time. The -a option prints all limits.
If limit is present, ulimit sets the specified limit to limit. The
string unlimited requests the largest valid limit. Limits may be set
for only one resource at a time. Any user may set a soft limit to any
value below the hard limit. Any user may lower a hard limit. Only a
super-user may raise a hard limit. See su(1M).
The -H option specifies a hard limit. The -S option specifies a soft
limit. If neither option is specified, ulimit will set both limits and
print 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)
csh
The 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. If limit is omitted, print the current limit;
if resource is omitted, display 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 privi‐
leged user may raise the hard limits.
resource is one of:
cputime Maximum CPU seconds per process.
filesize Largest single file allowed. Limited by the size 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 hexadeci‐
mal, 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 follows:
nh Hours (for cputime).
nk n kilobytes. This is the default for all but cputime.
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 of resource names.
-h Remove corresponding hard limits. Only the privileged user may do
this.
ksh
The Korn shell built-in function, ulimit, sets or displays a resource
limit. The available resources limits are listed below. Many systems do
not contain one or more of these limits. 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 -H and -S flags specify whether the hard limit or the
soft limit for the given 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. If neither the -H or -S options is specified, the
limit applies to both. The current resource limit is printed when limit
is omitted. In this case, the soft limit is printed unless -H is speci‐
fied. 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 may 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.
If no option is given, -f is assumed.
Per-Shell Memory Parameters
The heapsize, datasize, and stacksize parameters are not system tun‐
ables. The only controls for these are hard limits, set in a shell
startup file, or system-wide soft limits, which, for the current ver‐
sion of the Solaris OS, is 2^64bytes.
OPTIONS
The following option is supported by 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.
OPERANDS
The following operand is supported by 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 Size
The following example limits the stack size to 512 kilobytes:
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 Size
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 environment variables
that affect the execution of ulimit: LANG, LC_ALL, LC_CTYPE, LC_MES‐
SAGES, and NLSPATH.
EXIT STATUS
The following exit values are returned by ulimit:
0 Successful completion.
>0 A request for a higher limit was rejected or an error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSObc(1), csh(1), ksh(1), sh(1), df(1M), su(1M), swap(1M), sysdef(1M),
getrlimit(2), attributes(5), environ(5), standards(5)SunOS 5.10 20 May 2010 limit(1)
