[PATCH] sleep: improve doc

[Paul Eggert]

Problem reported by Robert Elz.
* doc/coreutils.texi (sleep invocation):
Say that arguments must be non-negative, which means they cannot
be arbitrary floating-point numbers.  Mention POSIX, not
“historical implementations” that are no longer of practical
interest.  List the extensions to POSIX.
* src/sleep.c (usage): Omit needless words, removing dubious
commentary about “most implementations” and incorrect commentary
about “arbitrary”.  Details about exactly which numbers are
allowed can be found in the documentation.
---
 doc/coreutils.texi | 10 +++++-----
 src/sleep.c        |  5 ++---
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 419417efa..e9af80b7a 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -18121,7 +18121,7 @@ sleep @var{number}[smhd]@dots{}
 @end example
 
 @cindex time units
-Each argument is a number followed by an optional unit; the default
+Each argument is a non-negative number followed by an optional unit; the 
default
 is seconds.  The units are:
 
 @table @samp
@@ -18135,10 +18135,10 @@ hours
 days
 @end table
 
-Historical implementations of @command{sleep} have required that
-@var{number} be an integer, and only accepted a single argument
-without a suffix.  However, GNU @command{sleep} accepts
-arbitrary floating point numbers.  @xref{Floating point}.
+Although portable POSIX scripts must give @command{sleep} a single
+non-negative integer argument without a suffix, GNU @command{sleep}
+also accepts two or more arguments, unit suffixes, and floating-point
+numbers.  @xref{Floating point}.
 
 The only options are @option{--help} and @option{--version}.  @xref{Common
 options}.
diff --git a/src/sleep.c b/src/sleep.c
index 1fc398a51..23a941636 100644
--- a/src/sleep.c
+++ b/src/sleep.c
@@ -51,9 +51,8 @@ usage (int status)
 Usage: %s NUMBER[SUFFIX]...\n\
   or:  %s OPTION\n\
 Pause for NUMBER seconds.  SUFFIX may be 's' for seconds (the default),\n\
-'m' for minutes, 'h' for hours or 'd' for days.  Unlike most implementations\n\
-that require NUMBER be an integer, here NUMBER may be an arbitrary floating\n\
-point number.  Given two or more arguments, pause for the amount of time\n\
+'m' for minutes, 'h' for hours or 'd' for days.  NUMBER need not be an\n\
+integer.  Given two or more arguments, pause for the amount of time\n\
 specified by the sum of their values.\n\
 \n\
 "),
-- 
2.17.1