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

In UTF-8 it's actually 6 digits (or 3 bytes).

$ printf '\xE2\x98\xA0'
☠

To check how it's encoded by the console, use hexdump:

$ printf ☠ | hexdump
0000000 98e2 00a0                              
0000003

% echo -e '\u2620'     # \u takes four hexadecimal digits
☠
% echo -e '\U0001f602' # \U takes eight hexadecimal digits

This works in Zsh (I've checked version 4.3) and in Bash 4.2 or newer.

Just put "☠" in your shell script. In the correct locale and on a Unicode-enabled console it'll print just fine:

$ echo ☠
☠
$

An ugly "workaround" would be to output the UTF-8 sequence, but that also depends on the encoding used:

$ echo -e '\xE2\x98\xA0'
☠
$

In bash to print a Unicode character to output use \x,\u or \U (first for 2 digit hex, second for 4 digit hex, third for any length)

echo -e '\U1f602'

I you want to assign it to a variable use $'...' syntax

x=$'\U1f602'
echo $x

Here is a list of all unicode emoji's available:

https://en.wikipedia.org/wiki/Emoji#Unicode_blocks

Example:

echo -e "\U1F304"

For get the ASCII value of this character use hexdump

echo -e "" | hexdump -C

00000000  f0 9f 8c 84 0a                                    |.....|
00000005

And then use the values informed in hex format

echo -e "\xF0\x9F\x8C\x84\x0A"

I'm using this:

$ echo -e '\u2620'
☠

This is pretty easier than searching a hex representation... I'm using this in my shell scripts. That works on gnome-term and urxvt AFAIK.

If you don't mind a Perl one-liner:

$ perl -CS -E 'say "\x{2620}"'
☠

-CS enables UTF-8 decoding on input and UTF-8 encoding on output. -E evaluates the next argument as Perl, with modern features like say enabled. If you don't want a newline at the end, use print instead of say.

In Bash:

UnicodePointToUtf8()
{
    local x="$1"               # ok if '0x2620'
    x=${x/\\u/0x}              # '\u2620' -> '0x2620'
    x=${x/U+/0x}; x=${x/u+/0x} # 'U-2620' -> '0x2620'
    x=$((x)) # from hex to decimal
    local y=$x n=0
    [ $x -ge 0 ] || return 1
    while [ $y -gt 0 ]; do y=$((y>>1)); n=$((n+1)); done
    if [ $n -le 7 ]; then       # 7
        y=$x
    elif [ $n -le 11 ]; then    # 5+6
        y=" $(( ((x>> 6)&0x1F)+0xC0 )) \
            $(( (x&0x3F)+0x80 ))" 
    elif [ $n -le 16 ]; then    # 4+6+6
        y=" $(( ((x>>12)&0x0F)+0xE0 )) \
            $(( ((x>> 6)&0x3F)+0x80 )) \
            $(( (x&0x3F)+0x80 ))"
    else                        # 3+6+6+6
        y=" $(( ((x>>18)&0x07)+0xF0 )) \
            $(( ((x>>12)&0x3F)+0x80 )) \
            $(( ((x>> 6)&0x3F)+0x80 )) \
            $(( (x&0x3F)+0x80 ))"
    fi
    printf -v y '\\x%x' $y
    echo -n -e $y
}

# test
for (( i=0x2500; i<0x2600; i++ )); do
    UnicodePointToUtf8 $i
    [ "$(( i+1 & 0x1f ))" != 0 ] || echo ""
done
x='U+2620'
echo "$x -> $(UnicodePointToUtf8 $x)"

Output:

─━│┃┄┅┆┇┈┉┊┋┌┍┎┏┐┑┒┓└┕┖┗┘┙┚┛├┝┞┟
┠┡┢┣┤┥┦┧┨┩┪┫┬┭┮┯┰┱┲┳┴┵┶┷┸┹┺┻┼┽┾┿
╀╁╂╃╄╅╆╇╈╉╊╋╌╍╎╏═║╒╓╔╕╖╗╘╙╚╛╜╝╞╟
╠╡╢╣╤╥╦╧╨╩╪╫╬╭╮╯╰╱╲╳╴╵╶╷╸╹╺╻╼╽╾╿
▀▁▂▃▄▅▆▇█▉▊▋▌▍▎▏▐░▒▓▔▕▖▗▘▙▚▛▜▝▞▟
■□▢▣▤▥▦▧▨▩▪▫▬▭▮▯▰▱▲△▴▵▶▷▸▹►▻▼▽▾▿
◀◁◂◃◄◅◆◇◈◉◊○◌◍◎●◐◑◒◓◔◕◖◗◘◙◚◛◜◝◞◟
◠◡◢◣◤◥◦◧◨◩◪◫◬◭◮◯◰◱◲◳◴◵◶◷◸◹◺◻◼◽◾◿
U+2620 -> ☠

Easy with a Python2/3 one-liner:

$ python -c 'print u"\u2620"'    # python2
$ python3 -c 'print(u"\u2620")'  # python3

Results in:

☠