How to add an icon to the bash prompt

Question

I know you can edit the bash prompt permanently by editing the PS1 variable in your ~/.bashrc file, mine looks like this:

PS1="\[\e[0;31m\]<HERP(._.)DERP>\[\e[0;0m\]";

but can you set a tiny little image in there as well? For instance, if I wanted to add a little American flag icon, or something before "HERP(._.)DERP", could I do this?

Solution 1

Sorry, no. Terminals don't do graphics.

For a full description of what you can do, see the PROMPTING section of the bash(1) man page:

PROMPTING

When executing interactively, bash displays the primary prompt PS1 when it is ready to read a command, and the secondary prompt PS2 when it needs more input to complete a command. Bash allows these prompt strings to be customized by inserting a number of backslash-escaped special characters that are decoded as follows:

\a     an ASCII bell character (07)
\d     the date in "Weekday Month Date" format (e.g., "Tue May 26")
\D{format}
       the  format  is  passed to strftime(3) and the result is inserted into the
       prompt string; an empty format results in a locale-specific time
       representation. The braces are required
\e     an ASCII escape character (033)
\h     the hostname up to the first ‘.’
\H     the hostname
\j     the number of jobs currently managed by the shell
\l     the basename of the shell’s terminal device name
\n     newline
\r     carriage return
\s     the name of the shell, the basename of $0 (the portion following the final
       slash)
\t     the current time in 24-hour HH:MM:SS format
\T     the current time in 12-hour HH:MM:SS format
\@     the current time in 12-hour am/pm format
\A     the current time in 24-hour HH:MM format
\u     the username of the current user
\v     the version of bash (e.g., 2.00)
\V     the release of bash, version + patch level (e.g., 2.00.0)
\w     the current working directory, with $HOME abbreviated with a tilde (uses the
       value of the PROMPT_DIRTRIM variable)
\W     the basename of the current working directory, with $HOME abbreviated with a
       tilde
\!     the history number of this command
\#     the command number of this command
\$     if the effective UID is 0, a #, otherwise a $
\nnn   the character corresponding to the octal number nnn
\\     a backslash
\[     begin a sequence of non-printing characters, which could be used to embed a
       terminal control sequence into the prompt
\]     end a sequence of non-printing characters

The command number and the history number are usually different: the history number of a command is its position in the history list, which may include commands restored from the history file (see HISTORY below), while the command number is the position in the sequence of commands executed during the current shell session. After the string is decoded, it is expanded via parameter expansion, command substitution, arithmetic expansion, and quote removal, subject to the value of the promptvars shell option (see the description of the shopt command under SHELL BUILTIN COMMANDS below).

The \e, \[ and \] escape sequences deserve special attention. With these you can insert ANSI escape codes to command the terminal to change foreground color, background color, move the cursor, erase parts of the screen, and do other fancy tricks.

That is, for instance, how your prompt changes color. \[\e[0;31m\] sets the foreground color to red, and \[\e[0;0m\] resets it back to the default.

Solution 2

Actually, Yes, you can.

In recent versions of Bash, at least 4 (i could do it in 4.2 and 4.3), you can render emoji with the hex.

Use the echo -e flag.

paste an emoji you looked up in and do a hexdump to see what it's made of:

plasmarob ~ $ echo -n "🇺🇸"| hexdump

0000000 f0 9f 87 ba f0 9f 87 b8                        
0000008

And then take that top line and escape each hex pair with \x :

plasmarob ~ $ echo -e 'See? \xf0\x9f\x87\xba\xf0\x9f\x87\xb8'
See? 🇺🇸

I actually modified mine to be:

plasmarob ~ ⚡

So yes, come up with one like this and try adding it to your .bashrc or .bash_profile.

Edit: Something with SO or browser rendering may have changed because the flag in this post now renders as a "US" character. YMMV but i assume it will still work in the stated versions of bash.

Solution 3

Nowadays, you can add emoji if you have an emoji-aware font. I guess this wasn't a easily viable option when the question was originally posted

I wrote this blog post about it a couple of years ago.

I don't know about American flags, but export PS1="\360\237\232\251 > " gets a flag in your prompt.

I also wrote a shell tool to make printing the escapes for echo or shell prompt a little easier. It's called emo

Solution 4

The closer you'll get are white and black flags:

⚐ → U+2690 ; WHITE FLAG
⚑ → U+2691 ; BLACK FLAG

The above are Unicode characters. You could also look for a font with flags - I don't know of any.

View more solutions

Comments

[Camilo Martin]

One could also hack a font to support a non-existant character for this reason. Like editing a random code point with an image. So much useless work done, though.

[Plasmarob]

This isn't completely precise, as some modern terminals do support emoji, such as the aforementioned American flag. Try: echo -e '\xf0\x9f\x87\xba\xf0\x9f\x87\xb8'

[Nik]

Some versions of hexdump may need to be run with the -C option to respect the endian-ness. unix.stackexchange.com/questions/55770/…

[Plasmarob]

Good point just in case. If I still had access to the environment where I ran these I'd run a few tests with hexdump, to see what else I can pull off. My current environment is through putty so my characters are more limited. If anyone knows how to expand putty character support I'm all ears.

[Andrew Kirna]

@Plasmarob, am I supposed to do something special with that hexcode in my PS1? I pasted it in, but terminal just shows that exact string.

[Plasmarob]

@AndrewKirna copy/paste from place to place often causes problems. A good preliminary test is to try to paste emoji onto the command line and see how it is rendered (or not rendered)

[Andrew Kirna]

@Plasmarob, it pastes fine but still takes the space of two characters visually while only registering one space with bash. More details in my post here: stackoverflow.com/q/54451605/5739507

[Lonnie Best]

When I run echo -e 'See? \xf0\x9f\x87\xba\xf0\x9f\x87\xb8', I get this output.

[Lonnie Best]

That blog post is gone now.

[cms]

ah, so it has, thanks! A victim of blog migrations. It's over here now beatworm.co.uk/blog/computers/Cool-Shell-Prompts (now case sensitive I guess) , but the screenshots are missing, I'll see if i can find them before i correct the link

[Plasmarob]

@LonnieBest looks like your console doesn't support it. You may be using an older console or likely you're not using Bash 4.x, last I checked many systems never left 3.x - last I checked Apple still uses their own fork of bash 3.x. You can manually install bash 4.x yourself, I did on a macbook back in the day.