printf field width doesn't support multibyte characters?

Question

I want printf to recognize multi-byte characters when calculating the field width so that columns line up properly... I can\'t find an answer to this problem and was wonderi

Answer 1

I will probably use GNU awk:

awk 'BEGIN{ printf "## %5s %5s %5s ##\n## %5s %5s %5s ##\n", "", "*", "", "", "•", "" }'
##           *       ##
##           •       ##

You can even write shell wrapper function called printf on top of awk to keep same interface:

tr2awk() { 
    FMT="$1"
    echo -n "gawk 'BEGIN{ printf \"$FMT\""
    shift
    for ARG in "$@"
        do echo -n ", \"$ARG\""
    done
    echo " }'"
}

and then override printf with simple function:

printf() { eval `tr2awk "$@"`; }

Test it:

# buggy printf binary test:
/usr/bin/printf "## %5s %5s %5s ##\n## %5s %5s %5s ##\n" '' '*' '' '' "•" ''
##           *       ##
##         •       ##
# buggy printf shell builin test:
builtin printf "## %5s %5s %5s ##\n## %5s %5s %5s ##\n" '' '*' '' '' "•" ''
##           *       ##
##         •       ##

# fixed printf function test:
printf "## %5s %5s %5s ##\n## %5s %5s %5s ##\n" '' '*' '' '' "•" ''
##           *       ##
##           •       ##