limit(1) 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-
dents
SYNOPSIS
/usr/bin/ulimit [ -f ] [ _b_l_o_c_k_s ]
sh
ulimit [ -[ HS ] [ a | cdfnstv ] ]
ulimit [ -[ HS ] ] c | d | f | n | s | t | v ] ] _l_i_m_i_t
csh
limit [ -h ] [ _r_e_s_o_u_r_c_e [ _l_i_m_i_t ] ]
unlimit [ -h ] [ _r_e_s_o_u_r_c_e ]
ksh
ulimit [ -HSacdfnstv ] [ _l_i_m_i_t ]
AVAILABILITY
SUNWcsu
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 _l_i_m_i_t 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 _l_i_m_i_t is present, ulimit sets the specified limit to
_l_i_m_i_t. 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 speci-
fies 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.
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limit(1) User Commands limit(1)
-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 _l_i_m_i_t on the specified _r_e_s_o_u_r_c_e. If
_l_i_m_i_t is omit-
ted, print the current limit; if _r_e_s_o_u_r_c_e is omitted,
display all limits. (Run the sysdef(1M) command to obtain
the maximum possible limits for your system. The values
reported are in hexidecimal, but can be translated into
decimal numbers using the bc(1) command).
-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 may raise the hard
limits.
_r_e_s_o_u_r_c_e is one of:
cputime Maximum CPU seconds per process.
filesize Largest single file allowed; limited to
the size of the filesystem. (see
df(1M)).
datasize (heapsize)
Maximum data size (including stack) for
the process. This is the size of your
virtual memory (see swap(1M)).
stacksize Maximum stack size for the process.
(see swap(1M)).
coredumpsize Maximum size of a core dump (file).
This limited to the size of the filesys-
tem.
descriptors Maximum number of file descriptors.
(run sysdef()).
memorysize Maximum size of virtual memory.
_l_i_m_i_t is a number, with an optional scaling factor, as fol-
lows:
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limit(1) User Commands limit(1)
_nh Hours (for cputime).
_nk _n kilobytes. This is the default for all
but cputime.
_nm _n megabytes or minutes (for cputime).
_m_m:_s_s Minutes and seconds (for cputime).
unlimit removes a limitation on _r_e_s_o_u_r_c_e. If no
_r_e_s_o_u_r_c_e 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
_l_i_m_i_t is specified. The value of _l_i_m_i_t 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 _l_i_m_i_t is omitted.
In this case the soft limit is printed unless H is speci-
fied. When more that 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.
OPTIONS
The following option is supported by ulimit:
-f Set (or report, if no _b_l_o_c_k_s operand is present),
the file size limit in blocks. The -f option is
also the default case.
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limit(1) User Commands limit(1)
OPERANDS
The following operand is supported by ulimit:
_b_l_o_c_k_s The number of 512-byte blocks to use as the new file
size limit.
EXAMPLES
/usr/bin/ulimit
To limit the stack size to 512 kilobytes:
% ulimit -s 512
% 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
To limit the number of file descriptors to 12:
$ ulimit -n 12
$ ulimit -a
time(seconds) unlimited
file(blocks) 41943
data(kbytes) 523256
stack(kbytes) 8192
coredump(blocks) 200
nofiles(descriptors) 12
vmemory(kbytes) unlimited
csh
To limit the size of a core dump file size to 0 kilobytes:
% limit coredumpsize 0
% limit
cputime unlimited
filesize unlimited
datasize 523256 kbytes
stacksize 8192 kbytes
coredumpsize 0 kbytes
descriptors 64
memorysize unlimited
To remove the above limitation for the core file size:
% unlimit coredumpsize
% limit
cputime unlimited
filesize unlimited
datasize 523256 kbytes
stacksize 8192 kbytes
coredumpsize unlimited
descriptors 64
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limit(1) User Commands limit(1)
memorysize unlimited
ENVIRONMENT
See environ(5) for descriptions of the following environment
variables that affect the execution of ulimit: LC_CTYPE,
LC_MESSAGES, 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.
SEE ALSO
bc(1), csh(1), ksh(1), sh(1), su(1M), df(1M), swap(1M),
sysdef(1M), getrlimit(2)
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