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

Are these the only way? There's no way to do it with printf alone?

Well with the example from ninjalj (thx btw), I wrote a script to deal with this problem, and saved it as fprintf in /usr/local/bin:

#! /bin/bash

IFS=' '
declare -a Text=("${@}")

## Skip the whole thing if there are no multi-byte characters ##
if (( $(echo "${Text[*]}" | wc -c) > $(echo "${Text[*]}" | wc -m) )); then
    if echo "${Text[*]}" | grep -Eq '%[#0 +-]?[0-9]+(\.[0-9]+)?[sb]'; then
        IFS=$'\n'
        declare -a FormatStrings=($(echo -n "${Text[0]}" | grep -Eo '%[^%]*?[bs]'))
        IFS=$' \t\n'
        declare -i format=0

    ## Check every format string ##
        for fw in "${FormatStrings[@]}"; do
            (( format++ ))
            if [[ "$fw" =~ ^%[#0\ +-]?[1-9][0-9]*(\.[1-9][0-9]*)?[sb]$ ]]; then
                (( Difference = $(echo "${Text[format]}" | wc -c) - $(echo "${Text[format]}" | wc -m) ))

            ## If multi-btye characters ##
                if (( Difference > 0 )); then

                ## If a field width is entered then replace field width value ##
                    if [[ "$fw" =~ ^%[#0\ +-]?[1-9][0-9]* ]]; then
                        (( Width = $(echo -n "$fw" | gsed -re 's|^%[#0 +-]?([1-9][0-9]*).*[bs]|\1|') + Difference ))
                        declare -a Text[0]="$(echo -n "${Text[0]}" | gsed -rne '1h;1!H;${g;y|\n|\x1C|;s|(%[^%])|\n\1|g;p}' | gsed -rne $(( format + 1 ))'s|^(%[#0 +-]?)[1-9][0-9]*|\1'${Width}'|;1h;1!H;${g;s|\n||g;y|\x1C|\n|;p}')"
                    fi

                ## If a precision is entered then replace precision value ##
                    if [[ "$fw" =~ \.[1-9][0-9]*[sb]$ ]]; then
                        (( Precision = $(echo -n "$fw" | gsed -re 's|^%.*\.([1-9][0-9]*)[sb]$|\1|') + Difference ))
                        declare -a Text[0]="$(echo -n "${Text[0]}" | gsed -rne '1h;1!H;${g;y|\n|\x1C|;s|(%[^%])|\n\1|g;p}' | gsed -rne $(( format + 1 ))'s|^(%[#0 +-]?([1-9][0-9]*)?)\.[1-9][0-9]*([bs])|\1.'${Precision}'\3|;1h;1!H;${g;s|\n||g;y|\x1C|\n|;p}')"
                    fi
                fi
            fi
        done
    fi
fi

printf "${Text[@]}"
exit 0

Usage: fprintf "## %5s %5s %5s ##\n## %5s %5s %5s ##\n" '' '*' '' '' '•' ''

A few things to note:

• I didn't write this script to deal with * (asterisk) values for formats because I never use them. I wrote this for me and didn't want to over-complicate things.
• I wrote this to check only the format strings %s and %b as they seem to be the only ones that are affected by this problem. Thus, if somehow someone manages to get a multi-byte unicode character out of a number, it may not work without minor modification.
• The script works great for basic use of printf (not some old-skooler UNIX hacker), feel free to modify, or use as is all!