procps/doc/procps_uptime.3
Craig Small 6b5cb345c5 library: procps_uptime() return value is a status
procps_uptime, previously just plain uptime() used to put the
uptime (as a double) in the first argument and return uptime
(as an int).

It meant if you ran
 myuptime2 = procps_uptime(&myuptime1, NULL);
You might get different results for myuptime1 and myuptime2 because
they are different types.

Most library calls use the return value to return the status,
procps_uptime was in the middle.

Until now.

This function will return 0 on success. If you want (for whatever
reason) uptime as an int then cast it.

All of the procps binaries didn't use the return value for uptime
except ps which set a variable to it but never used it anywhere.
2016-05-01 16:50:25 +10:00

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.\" (C) Copyright 2016 Craig Small <csmall@enc.com.au>
.\"
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.TH PROCPS_UPTIME 3 2016-05-01 "libproc-2"
.\" Please adjust this date whenever revising the manpage.
.\"
.SH NAME
procps_uptime \-
provide the uptime and idle time in seconds
.SH SYNOPSIS
.B #include <proc/procps.h>
.sp
.BI "int procps_uptime(double * " uptime_secs ", double * " idle_secs ");"
.sp
Link with \fI\-lprocps\fP.
.SH DESCRIPTION
The function
.BR procps_uptime ()
fills the location of the two double points with the current sytem uptime
and idle time.
.SH RETURN VALUE
.BR procps_uptime ()
returns 0 on success. On failure, it
returns a negative integer to one of the values defined below.
.TP
.B -ERANGE
Unable to parse the uptime file.
.PP
.BR procps_uptime ()
may also return any (negated) value that \fBfopen\fR() may set errno to.
.SH FILES
.TP
.I /proc/uptime
The raw values for uptime and idle time.
.SH VERSIONS
.B procps_uptime()
first appeared in libproc-2 version 0.0.
.SH SEE ALSO
.BR fopen (3),
.BR proc (5).