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32 .\" @(#)getitimer.2 8.3 (Berkeley) 5/16/95
33 .\" $FreeBSD: src/lib/libc/sys/getitimer.2,v 1.10.2.6 2001/12/14 18:34:00 ru Exp $
34 .\" $DragonFly: src/lib/libc/sys/getitimer.2,v 1.2 2003/06/17 04:26:47 dillon Exp $
42 .Nd get/set value of interval timer
47 .Fd "#define ITIMER_REAL 0"
48 .Fd "#define ITIMER_VIRTUAL 1"
49 .Fd "#define ITIMER_PROF 2"
51 .Fn getitimer "int which" "struct itimerval *value"
53 .Fn setitimer "int which" "const struct itimerval *value" "struct itimerval *ovalue"
55 The system provides each process with three interval timers,
57 .Ao Pa sys/time.h Ac .
60 call returns the current value for the timer specified in
66 call sets a timer to the specified
68 (returning the previous value of the timer if
72 A timer value is defined by the
75 .Bd -literal -offset indent
77 struct timeval it_interval; /* timer interval */
78 struct timeval it_value; /* current value */
84 is non-zero, it indicates the time to the next timer expiration.
87 is non-zero, it specifies a value to be used in reloading
89 when the timer expires.
92 to 0 disables a timer, regardless of the value of
96 to 0 causes a timer to be disabled after its next expiration (assuming
100 Time values smaller than the resolution of the
101 system clock are rounded up to this resolution
102 (typically 10 milliseconds).
106 timer decrements in real time. A
109 delivered when this timer expires.
113 timer decrements in process virtual time.
114 It runs only when the process is executing. A
117 is delivered when it expires.
121 timer decrements both in process virtual time and
122 when the system is running on behalf of the process. It is designed
123 to be used by interpreters in statistically profiling the execution
124 of interpreted programs.
130 delivered. Because this signal may interrupt in-progress
131 system calls, programs using this timer must be prepared to
132 restart interrupted system calls.
134 The maximum number of seconds allowed for
142 Three macros for manipulating time values are defined in
143 .Ao Pa sys/time.h Ac .
145 sets a time value to zero,
147 tests if a time value is non-zero, and
149 compares two time values.
161 parameter specified a bad address.
165 parameter specified a time that was too large
176 function call appeared in