I installed this documentation to clarify how "printf" behave.
2004-08-18 Paul Eggert <[EMAIL PROTECTED]>
* coreutils.texi (printf invocation): Clarify how "printf" is
supposed to work with extra arguments, missing arguments, etc.
Index: coreutils.texi
===================================================================
RCS file: /home/eggert/coreutils/cu/doc/coreutils.texi,v
retrieving revision 1.199
retrieving revision 1.200
diff -p -u -r1.199 -r1.200
--- coreutils.texi 10 Aug 2004 22:07:31 -0000 1.199
+++ coreutils.texi 18 Aug 2004 20:22:32 -0000 1.200
@@ -9101,9 +9101,60 @@ printf @var{format} [EMAIL PROTECTED]@dot
@end example
@command{printf} prints the @var{format} string, interpreting @samp{%}
-directives and @samp{\} escapes in the same way as the C @command{printf}
-function. The @var{format} argument is re-used as necessary to convert
-all of the given @var{argument}s.
+directives and @samp{\} escapes to format numeric and string arguments
+in a way that is mostly similar to the C @samp{printf} function. The
+differences are as follows:
+
[EMAIL PROTECTED] @bullet
+
[EMAIL PROTECTED]
+The @var{format} argument is reused as necessary to convert all the
+given @var{argument}s. For example, the command @samp{printf %s a b}
+outputs @samp{ab}.
+
[EMAIL PROTECTED]
+Missing @var{argument}s are treated as null strings or as zeros,
+depending on whether the context expects a string or a number. For
+example, the command @samp{printf %sx%d} prints @samp{x0}.
+
[EMAIL PROTECTED]
[EMAIL PROTECTED] \c
+An additional escape, @samp{\c}, causes @command{printf} to produce no
+further output. For example, the command @samp{printf 'A%sC\cD%sF' B
+E} prints @samp{ABC}.
+
[EMAIL PROTECTED]
+The hexadecimal escape sequence @[EMAIL PROTECTED] has at most two
+digits, as opposed to C where it can have an unlimited number of
+digits. For example, the command @samp{printf '\x07e'} prints two
+bytes, whereas the C statement @samp{printf ("\x07e")} prints just
+one.
+
[EMAIL PROTECTED]
[EMAIL PROTECTED] %b
[EMAIL PROTECTED] has an additional directive, @samp{%b}, which prints its
+argument string with @samp{\} escapes interpreted in the same way as in
+the @var{format} string, except that octal escapes are of the form
[EMAIL PROTECTED]@var{ooo}} where @var{ooo} is 0 to 3 octal digits.
+If a precision is also given, it limits the number of bytes printed
+from the converted string.
+
[EMAIL PROTECTED]
+Numeric arguments must be single C constants, possibly with leading
[EMAIL PROTECTED] or @samp{-}. For example, @samp{printf %.4d -3} outputs
[EMAIL PROTECTED]
+
[EMAIL PROTECTED]
[EMAIL PROTECTED] POSIXLY_CORRECT
+If the leading character of a numeric argument is @samp{"} or @samp{'}
+then its value is the numeric value of the immediately following
+character. Any remaining characters are silently ignored if the
[EMAIL PROTECTED] environment variable is set; otherwise, a
+warning is printed. For example, @samp{printf "%d" "'a"} outputs
[EMAIL PROTECTED] on hosts that use the @acronym{ASCII} character set, since
[EMAIL PROTECTED] has the numeric value 97 in @acronym{ASCII}.
+
[EMAIL PROTECTED] itemize
@vindex LC_NUMERIC
A floating-point argument must use a period before any fractional
@@ -9112,14 +9163,8 @@ current locale. For example, in a local
comma, the command @samp{printf %g 3.14} outputs @samp{3,14} whereas
the command @samp{printf %g 3,14} is an error.
[EMAIL PROTECTED] has one additional directive, @samp{%b}, which prints its
-argument string with @samp{\} escapes interpreted in the same way as in
-the @var{format} string, except that octal escapes are of the form
[EMAIL PROTECTED]@var{ooo}} where @var{ooo} is 0 to 3 octal digits.
-
@kindex [EMAIL PROTECTED]
@kindex [EMAIL PROTECTED]
-
@command{printf} interprets @[EMAIL PROTECTED] in @var{format} as an octal number
(if @var{ooo} is 1 to 3 octal digits) specifying a character to print,
and @[EMAIL PROTECTED] as a hexadecimal number (if @var{hh} is 1 to 2 hex
@@ -9139,10 +9184,6 @@ The processing of @samp{\u} and @samp{\U
@code{iconv} facility. It is activated on systems with glibc 2.2 (or newer),
or when @code{libiconv} is installed prior to this package. Otherwise the
use of @samp{\u} and @samp{\U} will give an error message.
-
[EMAIL PROTECTED] \c
-An additional escape, @samp{\c}, causes @command{printf} to produce no
-further output.
The only options are a lone @option{--help} or
@option{--version}. @xref{Common options}.
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