.\" Copyright (c) 1980, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\" %sccs.include.redist.man%
.\" @(#)getrlimit.2 8.1 (Berkeley) %G%
.Nd control maximum system resource consumption
.Fd #include <sys/types.h>
.Fd #include <sys/time.h>
.Fd #include <sys/resource.h>
.Fn getrlimit "int resource" "struct rlimit *rlp"
.Fn setrlimit "int resource" "struct rlimit *rlp"
Limits on the consumption of system resources by the current process
and each process it creates may be obtained with the
parameter is one of the following:
.Bl -tag -width RLIMIT_FSIZEAA
The largest size (in bytes)
file that may be created.
The maximum amount of cpu time (in seconds) to be used by
The maximum size (in bytes) of the data segment for a process;
this defines how far a program may extend its break with the
The largest size (in bytes) file that may be created.
The maximum size (in bytes) which a process may lock into memory
The maximum number of open files for this process.
The maximum number of simultaneous processes for this user id.
The maximum size (in bytes) to which a process's resident set size may
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.
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.
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
structure is used to specify the hard and soft limits on a resource,
.Bd -literal -offset indent
quad_t rlim_cur; /* current (soft) limit */
quad_t rlim_max; /* hard limit */
Only the super-user may raise the maximum limits. Other users
within the range from 0 to
value for a limit is defined as
Because this information is stored in the per-process information,
this system call must be executed directly by the shell if it
is to affect all future processes created by the shell;
is thus a built-in command to
The system refuses to extend the data or stack space when the limits
would be exceeded in the normal way: a
call fails if the data space limit is reached.
When the stack limit is reached, the process receives
caught by a handler using the signal stack, this signal
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
generated; this normally terminates the process, but may be caught. When
the soft cpu time limit is exceeded, a signal
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
The address specified for
raised the maximum limit value, and the caller is not the super-user.
function call appeared in