Refactor nixos/bash prompt using bash function #389305
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goyalyashpal
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Mar 12, 2025
nixos/modules/programs/bash/bash.nix
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| set_prompt() { | ||
| if [ "$TERM" == "dumb" ] || [ ! -n "$INSIDE_EMACS" ]; then | ||
| return | ||
| fi | ||
|
|
||
| local PROMPT_COLOR="1;31m" | ||
| ((UID)) && PROMPT_COLOR="1;32m" | ||
| if [ -n "$INSIDE_EMACS" ]; then | ||
| # Emacs term mode doesn't support xterm title escape sequence (\e]0;) | ||
| PS1="\n\[\033[$PROMPT_COLOR\][\u@\h:\w]\\$\[\033[0m\] " | ||
| else | ||
| PS1="\n\[\033[$PROMPT_COLOR\][\[\e]0;\u@\h: \w\a\]\u@\h:\w]\\$\[\033[0m\] " | ||
|
|
||
| # Emacs term mode doesn't support xterm title escape sequence (\e]0;) | ||
| if [ ! -n "$INSIDE_EMACS" ]; then | ||
| local TITLE="\[\e]0;\u@\h: \w\a\]" | ||
| fi |
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oh wait, forgot inverting the ors to ands...
as the same condition[ ! -n "$INSIDE_EMACS" ] is showing up in both these blocks, and it being true in first block results in return rightaway; so, does it mean that the latter block (setting title) will never be run and so can be eliminated?
i tried git-blaming with github's UI, and sifted through these commits; but couldn't figure out the reason for the existence of second block:
if [ "$TERM" == "dumb" ] || [ ! -n "$INSIDE_EMACS" ]; then
return
fi
if [ ! -n "$INSIDE_EMACS" ]; then
local TITLE="\[\e]0;\u@\h: \w\a\]"
fi
... for dumb prompt using guard clause (invert-select logic) rather than
nested if-s.
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goyalyashpal
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Mar 12, 2025
goyalyashpal
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Mar 12, 2025
| @@ -87,7 +87,7 @@ in | |||
| return | |||
| fi | |||
| PROMPT_COLOR="1;31m" | |||
| local PROMPT_COLOR="1;31m" | |||
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this use of local is based on the observation that this bash variable ain't used anywhere outside this prompt configuration (atleast in this file).
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It simplifies the flow of logic and makes it easier to understand.
i was using this value (though read from a
.shfile) in myprograms.bash.promptInitfor 6 months, and it (seems) to work well with the default gnome terminal emulator and also theAlt-F2terminals.however, i have not tested it anywhere else nor tested it in this form (i.e. making changes to the underlying implementation itself)
Things done
nix.conf? (See Nix manual)sandbox = relaxedsandbox = truenix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage./result/bin/)Add a 👍 reaction to pull requests you find important.