Describe signal handling. Don't describe the old implementation. Don't

define `microsecond'.  Cleaned up English.

Obtained from:	mostly from sleep.3

1 files changed, 17 insertions, 35 deletions

diff --git a/lib/libc/gen/usleep.3 b/lib/libc/gen/usleep.3
index a56c56b..0b24929 100644
--- a/lib/libc/gen/usleep.3
+++ b/lib/libc/gen/usleep.3
@@ -30,50 +30,38 @@
 .\" SUCH DAMAGE.
 .\"
 .\"     @(#)usleep.3	8.1 (Berkeley) 6/4/93
+.\"     $Id$
 .\"
-.Dd June 4, 1993
+.Dd Feb 13, 1998
 .Dt USLEEP 3
 .Os BSD 4.3
 .Sh NAME
 .Nm usleep
-.Nd suspend execution for interval of microseconds
+.Nd suspend process execution for an interval measured in microseconds
 .Sh SYNOPSIS
 .Fd #include <unistd.h>
 .Ft int
-.Fn usleep "u_int microseconds"
+.Fn usleep "unsigned int microseconds"
 .Sh DESCRIPTION
 The
 .Fn usleep
-function
-suspends execution of the calling process
-for
-.Fa microseconds
-of time.
-System activity or time spent in processing the
-call may lengthen the sleep slightly.
-.Pp
-If a timer is already running on the process its state is unaltered by
-this
-.Fn usleep
-implementation.
-If the value
+function suspends execution of the calling process until either
 .Fa microseconds
-is more than or equal to the remaining clock time for the running timer,
-the sleep time is set to
-the remaining clock time.
+microseconds have elapsed or a signal is delivered to the process and its
+action is to invoke a signal-catching function or to terminate the
+process.
+System activity may lengthen the sleep by an indeterminate amount.
 .Pp
 This function is implemented using
 .Xr nanosleep 2
 by pausing for
 .Fa microseconds
-of time or until any signal occurse.
+microseconds or until a signal occurs.
+Consequently, in this implementation,
+sleeping has no effect on the state of process timers,
+and there is no special handling for SIGALRM.
 .Sh RETURN VALUES
-The
-.Fn usleep
-function returns 0 on successful completion. Otherwise, it returns -1
-and sets
-.Va errno
-to indicate the error.
+.Rv -std usleep
 .Sh ERRORS
 The
 .Fn usleep
@@ -81,17 +69,11 @@ function
 will fail if:
 .Bl -tag -width [EINTR]
 .It Bq Er EINTR
-Some signal occurse.
-.Sh NOTES
-.Pp
-A microsecond is 0.000001 seconds.
+A signal was delivered to the process and its
+action was to invoke a signal-catching function.
 .Sh SEE ALSO
 .Xr nanosleep 2 ,
-.Xr setitimer 2 ,
-.Xr alarm 3 ,
-.Xr signal 3 ,
-.Xr sleep 3 ,
-.Xr ualarm 3
+.Xr sleep 3
 .Sh HISTORY
 The
 .Fn usleep