How do you echo a 4-digit Unicode character in Bash?

Question

I\'d like to add the Unicode skull and crossbones to my shell prompt (specifically the \'SKULL AND CROSSBONES\' (U+2620)), but I can\'t figure out the magic incantation to m

Answer 1

Here's a fully internal Bash implementation, no forking, unlimited size of Unicode characters.

fast_chr() {
    local __octal
    local __char
    printf -v __octal '%03o' $1
    printf -v __char \\$__octal
    REPLY=$__char
}

function unichr {
    local c=$1    # Ordinal of char
    local l=0    # Byte ctr
    local o=63    # Ceiling
    local p=128    # Accum. bits
    local s=''    # Output string

    (( c < 0x80 )) && { fast_chr "$c"; echo -n "$REPLY"; return; }

    while (( c > o )); do
        fast_chr $(( t = 0x80 | c & 0x3f ))
        s="$REPLY$s"
        (( c >>= 6, l++, p += o+1, o>>=1 ))
    done

    fast_chr $(( t = p | c ))
    echo -n "$REPLY$s"
}

## test harness
for (( i=0x2500; i<0x2600; i++ )); do
    unichr $i
done

Output was:

─━│┃┄┅┆┇┈┉┊┋┌┍┎┏
┐┑┒┓└┕┖┗┘┙┚┛├┝┞┟
┠┡┢┣┤┥┦┧┨┩┪┫┬┭┮┯
┰┱┲┳┴┵┶┷┸┹┺┻┼┽┾┿
╀╁╂╃╄╅╆╇╈╉╊╋╌╍╎╏
═║╒╓╔╕╖╗╘╙╚╛╜╝╞╟
╠╡╢╣╤╥╦╧╨╩╪╫╬╭╮╯
╰╱╲╳╴╵╶╷╸╹╺╻╼╽╾╿
▀▁▂▃▄▅▆▇█▉▊▋▌▍▎▏
▐░▒▓▔▕▖▗▘▙▚▛▜▝▞▟
■□▢▣▤▥▦▧▨▩▪▫▬▭▮▯
▰▱▲△▴▵▶▷▸▹►▻▼▽▾▿
◀◁◂◃◄◅◆◇◈◉◊○◌◍◎●
◐◑◒◓◔◕◖◗◘◙◚◛◜◝◞◟
◠◡◢◣◤◥◦◧◨◩◪◫◬◭◮◯
◰◱◲◳◴◵◶◷◸◹◺◻◼◽◾◿