How can I clean a string in bashrc? - bash

Question

I'd like to know how to "clean up" a line of code in bash. I've created a string to colour the command line in my ~/.bashrc which looks like this:
PS1='\[\033[1;36m\]\u\[\033[1;31m\]#\[\033[1;32m\]\h:\[\033[1;35m\]\w\[\033[1;31m\]\$\[\033[0m\] '
I'd like to make it easier to discern. More something along these lines:
PS1='\[\033[1;36m\]
\u\[\033[1;31m\]
#\[\033[1;32m\]
\h:\[\033[1;35m\]
\w\[\033[1;31m\]
\$\[\033[0m\] '
I've tried putting these {} brackets but that didn't seem to work, either.
EDIT: thanks to tripleee. The code that works is as follows:
tprompt () {
local bold=$(tput bold)
local red=$(tput setaf 1)
local green=$(tput setaf 2)
local magenta=$(tput setaf 5)
local cyan=$(tput setaf 6)
local plain=$(tput sgr0)
printf -v PS1 "%s" "$bold" "$cyan" '\u' \
"$red" "#" \
"$green" '\h:' \
"$magenta" '\w' \
"$red" '\$' \
"$plain"
}
tprompt

Answer 1

A better overall approach might be to use tput to generate these codes, rather than hard-code them for a specific terminal. This also allows you to assign mnemonic names to them.
tprompt () {
local bold=$(tput bold)
local red=$(tput setaf 1)
local green=$(tput setaf 2)
local magenta=$(tput setaf 5)
local cyan=$(tput setaf 6)
local plain=$(tput sgr0)
printf -v PS1 "%s" "$bold" "$cyan" '\u' \
"$red" "#" \
"$green" '\h:' \
"$magenta" '\w' \
"$red" '\$' \
"$plain" ' '
}
tprompt
(Not sure I managed to correctly map back the escape codes to their meanings, but you should at least be able to see how this is more readable and maintainable than what you had. The sole reason to define a function for this is to create a local scope so the helper variables don't pollute the global namespace. We only call the function once; you could even undefine the function when you have called it, too.)
As an aside, notice also how printf lets you easily paste together multiple strings. Even if you don't adopt this approach wholesale, you might want to refactor to
printf -v PS1 '%s' \
'\[\033[1;36m\]' \
'\u\[\033[1;31m\]' \
'#\[\033[1;32m\]' \
'\h:\[\033[1;35m\]' \
'\w\[\033[1;31m\]' \
'\$\[\033[0m\] '
As a final aside, non-printing sequences in the prompt should be wrapped in \[ ... \] to tell Bash to disregard them when calculating the line length. Maybe wrap tput with a function, too:
tput () {
printf '\\['
command tput "$#"
printf '\\]'
}