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 make echo spit it, or any other, 4-digit Unicode character. Two-digit one's are easy. For example, echo -e "\x55", .
In addition to the answers below it should be noted that, obviously, your terminal needs to support Unicode for the output to be what you expect. gnome-terminal does a good job of this, but it isn't necessarily turned on by default.
On macOS's Terminal app Go to Preferences-> Encodings and choose Unicode (UTF-8).
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.