4.3BSD-Reno/share/man/cat2/getrlimit.0
GETRLIMIT(2) 1990 GETRLIMIT(2)
NNAAMMEE
getrlimit, setrlimit - control maximum system resource con-
sumption
SSYYNNOOPPSSIISS
##iinncclluuddee <<ssyyss//ttiimmee..hh>>
##iinncclluuddee <<ssyyss//rreessoouurrccee..hh>>
ggeettrrlliimmiitt((rreessoouurrccee,, rrllpp))
iinntt rreessoouurrccee;;
ssttrruucctt rrlliimmiitt **rrllpp;;
sseettrrlliimmiitt((rreessoouurrccee,, rrllpp))
iinntt rreessoouurrccee;;
ssttrruucctt rrlliimmiitt **rrllpp;;
DDEESSCCRRIIPPTTIIOONN
Limits on the consumption of system resources by the current
process and each process it creates may be obtained with the
_g_e_t_r_l_i_m_i_t call, and set with the _s_e_t_r_l_i_m_i_t call.
The _r_e_s_o_u_r_c_e parameter is one of the following:
RLIMIT_CPU the maximum amount of cpu time (in seconds)
to be used by each process.
RLIMIT_FSIZE the largest size, in bytes, of any single
file that may be created.
RLIMIT_DATA the maximum size, in bytes, of the data
segment for a process; this defines how far
a program may extend its break with the
_s_b_r_k(2) system call.
RLIMIT_STACK the maximum size, in bytes, of the stack
segment for a process; this defines how far
a program's stack segment may be extended.
Stack extension is performed automatically
by the system.
RLIMIT_CORE the largest size, in bytes, of a _c_o_r_e file
that may be created.
RLIMIT_RSS the maximum size, in bytes, to which a
process's resident set size may grow. This
imposes a limit on the amount of physical
memory to be given to a process; if memory
is tight, the system will prefer to take
memory from processes that are exceeding
their declared resident set size.
Printed 7/27/90 June 1
GETRLIMIT(2) 1990 GETRLIMIT(2)
A resource limit is specified as a soft limit and a hard
limit. When a soft limit is exceeded a process may receive
a signal (for example, if the cpu time or file size is
exceeded), but it will be allowed to continue execution
until it reaches the hard limit (or modifies its resource
limit). The _r_l_i_m_i_t structure is used to specify the hard
and soft limits on a resource,
struct rlimit {
int rlim_cur; /* current (soft) limit */
int rlim_max; /* hard limit */
};
Only the super-user may raise the maximum limits. Other
users may only alter _r_l_i_m__c_u_r within the range from 0 to
_r_l_i_m__m_a_x or (irreversibly) lower _r_l_i_m__m_a_x.
An "infinite" value for a limit is defined as RLIM_INFINITY
(0x7fffffff).
Because this information is stored in the per-process infor-
mation, this system call must be executed directly by the
shell if it is to affect all future processes created by the
shell; _l_i_m_i_t is thus a built-in command to _c_s_h(1).
The system refuses to extend the data or stack space when
the limits would be exceeded in the normal way: a _b_r_e_a_k call
fails if the data space limit is reached. When the stack
limit is reached, the process receives a segmentation fault
(SIGSEGV); if this signal is not caught by a handler using
the signal stack, this signal will kill the process.
A file I/O operation that would create a file larger that
the process' soft limit will cause the write to fail and a
signal SIGXFSZ to be generated; this normally terminates the
process, but may be caught. When the soft cpu time limit is
exceeded, a signal SIGXCPU is sent to the offending process.
RREETTUURRNN VVAALLUUEE
A 0 return value indicates that the call succeeded, changing
or returning the resource limit. A return value of -1
indicates that an error occurred, and an error code is
stored in the global location _e_r_r_n_o.
EERRRROORRSS
The possible errors are:
[EFAULT] The address specified for _r_l_p is invalid.
[EPERM] The limit specified to _s_e_t_r_l_i_m_i_t would have
raised the maximum limit value, and the
caller is not the super-user.
Printed 7/27/90 June 2
GETRLIMIT(2) 1990 GETRLIMIT(2)
SSEEEE AALLSSOO
csh(1), quota(2), sigvec(2), sigstack(2)
BBUUGGSS
There should be _l_i_m_i_t and _u_n_l_i_m_i_t commands in _s_h(1) as well
as in _c_s_h.
Printed 7/27/90 June 3