69 lines
2.6 KiB
Groff
69 lines
2.6 KiB
Groff
.TH GETITIMER 2 "April 14, 2006"
|
|
.UC 4
|
|
.SH NAME
|
|
getitimer, setitimer \- get and set value of interval timer
|
|
.SH SYNOPSIS
|
|
.nf
|
|
.ft B
|
|
#include <sys/time.h>
|
|
|
|
int getitimer(int \fIwhich\fP, struct itimerval *\fIvalue\fP)
|
|
.in +5
|
|
.ti -5
|
|
int setitimer(int \fIwhich\fP, const struct itimerval *\fIvalue\fP, struct itimerval *\fIovalue\fP);
|
|
.in -5
|
|
.ft R
|
|
.fi
|
|
.SH DESCRIPTION
|
|
.B Getitimer
|
|
retrieves the current value of the given interval timer, in \fIvalue\fP.
|
|
.PP
|
|
.B Setitimer
|
|
sets a new value for the given interval timer, as given in \fIvalue\fP, and, if \fIovalue\fP is not set to
|
|
.BR NULL ,
|
|
stores the old value for the interval timer in \fIovalue\fP.
|
|
.PP
|
|
For both functions, the \fIwhich\fP parameter indicates which of the interval timers they work on; \fIwhich\fP can have one of the following values:
|
|
.PP
|
|
.TP 15
|
|
.B ITIMER_REAL
|
|
A timer that is decremented in realtime. When it expires, a
|
|
.BR SIGARLM
|
|
signal is delivered to the process.
|
|
.TP
|
|
.B ITIMER_VIRTUAL
|
|
A timer that is decremented in process user time. When it expires, a
|
|
.BR SIGVTALRM
|
|
signal is delivered to the process.
|
|
.TP
|
|
.B ITIMER_PROF
|
|
A timer that is decremented in process user+system time. When it expires, a
|
|
.BR SIGPROF
|
|
signal is delivered to the process.
|
|
.PP
|
|
The specified timer will first expire after the time specified in the 'it_value' field of the itimerval structure. Similarly, upon retrieval the 'it_value' field will contain the time after which the timer will expire.
|
|
.PP
|
|
If 'it_value' is zero, then the timer is disabled, and the 'it_interval' field is ignored and (upon retrieval) set to zero. Otherwise, 'it_interval' contains the repetition interval after which the timer will repeatedly expire, starting from the moment that the timer expires for the first time according to the 'it_value' value. If 'it_interval' is set to zero, no repetition will occur.
|
|
.PP
|
|
The maximum supported timeout value that
|
|
.B setitimer
|
|
accepts, depends on the clock tick rate of the operating system.
|
|
.PP
|
|
These functions share their real-time timer with
|
|
.BR alarm (2).
|
|
Therefore, use of both types of functions in one program yields undefined results.
|
|
.SH RETURN VALUES
|
|
Upon successful completion, these functions return 0. Otherwise, a value of -1 is returned and \fIerrno\fP is set to indicate the error.
|
|
.SH ERRORS
|
|
The functions will fail if any of the following occur:
|
|
.TP 15
|
|
.B EINVAL
|
|
Either \fIwhich\fP is not one of the ITIMER_* constants above, or one of the timeval structures in \fIvalue\fP contains a bad or too large value.
|
|
.TP
|
|
.B EFAULT
|
|
Bad \fIvalue\fP or \fIovalue\fP address.
|
|
.SH SEE ALSO
|
|
.BR alarm (2)
|
|
.SH AUTHOR
|
|
David van Moolenbroek <dcvmoole@cs.vu.nl>
|