The argument operands shall be treated as strings if the corresponding
conversion specifier is b, c, or s ; otherwise, it shall be evaluated
as a C constant, as described by the ISO C standard, with the
following extensions:
[...]
* If the leading character is a single-quote or double-quote, the
value shall be the numeric value in the underlying codeset of the
character following the single-quote or double-quote.
I found myself wanting this recently in order to convert non-devfs disk device names into indices for display in a partitioning tool (e.g. /dev/hde => "IDE2 master (hde)"). Lacking any other way to map from a-z to 0-25 in shell that I can think of, it was going to have to be a messy sequence of sed commands until somebody pointed out this syntax to me. With this patch, I can just do:
printf '%d\n' "'$character"
... to map from a-z to 0-25, which is much nicer. The small attached patch implements this feature; I've checked it against the printf implementation in GNU coreutils.
printf-quote-codepoint.patch [^] (998 bytes) 01-05-06 06:11 
