commit b05a07373ba5884964e083f13329d8996fe6c482
parent 2beca7cba055dabe8cc125c85675617e1704b65a
Author: spacehobo <spacehobo@web>
Date: Fri, 15 May 2026 20:17:33 +0200
Hacks to make it work with pre-freedesktop.org environments on desktop.
Diffstat:
1 file changed, 29 insertions(+), 11 deletions(-)
diff --git a/spacehobo.mdwn b/spacehobo.mdwn
@@ -2,7 +2,7 @@
Hey, check out my neat `bash` prompt:
-```
+```{sh}
GIT_PS1_SHOWCOLORHINTS='y'
GIT_PS1_SHOWDIRTYSTATE='y'
GIT_PS1_SHOWSTASHSTATE='y'
@@ -10,24 +10,42 @@ GIT_PS1_SHOWUNTRACKEDFILES='y'
GIT_PS1_DESCRIBE_STYLE='contains'
GIT_PS1_SHOWUPSTREAM='auto'
-_noop[0]='array accesses turn 0/nonzero into defined/undef!'
+# We build the prompt from right to left, starting with a
+# $ or # that is either bold default, or blinking red
+# if $? is nonzero
+PS1='\[\e[$(($?==0?0:91));$(($?==0?1:5))m\]\$\[\e[0m\] '
+# Git branch information between gold curly braces
+PS1='$(__git_ps1 "\[\e[1;33m\]{%s\[\e[1;33m\]}")'$PS1
+# The only straightforward part: current directory in blue
+PS1='\[\e[1;34m\]\w'$PS1
+# If we ssh'd here, show the hostname in green
+PS1='${SSH_CONNECTION:+\[\e[1;32m\]\h\[\e[1;33m\]:}'$PS1
+# freedesktop.org defines the $XDG_SESSION_TYPE variable,
+# which is "tty" for sudo or ssh sessions, but this is kind of new.
+# So we default to tty but mess it up with as many environment
+# variables used by GUI desktop sessions to detect if you're local.
+# If this is our local machine and we didn't sudo, we should know
+# our username already! Otherwise if it's "tty", show it in purple.
+# If we did sudo, show the username we ran sudo under in red.
declare -A _session
_session["tty"]='array accesses turn tty/* into defined/undef!'
-PS1='\[\e[$(($?==0?0:91));$(($?==0?1:5))m\]\$\[\e[0m\] ' # $?-coloured $
-PS1='$(__git_ps1 "\[\e[1;33m\]{%s\[\e[1;33m\]}")'$PS1 # Gold git
-PS1='\[\e[1;34m\]\w'$PS1 # Blue CWD
-PS1='${SSH_CONNECTION:+\[\e[1;32m\]\h\[\e[1;33m\]:}'$PS1 # Green hostname, gold :
-PS1='${_session[$XDG_SESSION_TYPE]:+\[\e[1;35m\]\u${SUDO_USER:+\[\e[1;91m\]($SUDO_USER)}\[\e[1;33m\]@}'$PS1 # Purple username
-PS1='${debian_chroot:+\[\e[1;36m\]($debian_chroot)}'$PS1 # Cyan chroot
-PS1='${_noop[$((\j==0))]:+\[\e[1;33m\][\j]}'$PS1 # gold nonzero jobs
-PS1='${_noop[$(($?==0))]:+\[\e[1;91m\]($?)}'$PS1 # Red nonzero $?
+PS1='${_session[${XDG_SESSION_TYPE:-tty${TERMUX_VERSION}${!GNOME@}${!DESKTOP@}${!KDE@}}]:+\[\e[1;35m\]\u${SUDO_USER:+\[\e[1;91m\]($SUDO_USER)}\[\e[1;33m\]@}'$PS1
+# If the debian_chroot var is defined, show it in cyan.
+PS1='${debian_chroot:+\[\e[1;36m\]($debian_chroot)}'$PS1
+# If the number of jobs suspended/backgrounded is nonzero,
+# show it in yellow square brackets.
+_noop[0]='array accesses turn 0/nonzero into defined/undef!'
+PS1='${_noop[$((\j==0))]:+\[\e[1;33m\][\j]}'$PS1
+# Likewise if the last exit code was non-zero,
+# show it in red parentheses.
+PS1='${_noop[$(($?==0))]:+\[\e[1;91m\]($?)}'$PS1
```
The prompt environment is fairly limited. It can do parameter expansion, reference expansion, arithmetic expansion, and a couple other neat tricks. You can shell out, but if you do that overwrites the variable that contains the exit code of the last program you ran (`$?`). Tools such as the `__git_ps1` hacks do their best to only use features of bash that work internally to bash itself.
This prompt uses the `_noop` array (with only `${_noop[0]}` defined) to turn arithmetic expressions into defined/undefined responses. This lets us use some of the brace-expansion features to specify alternate output, so we can display the error code or number of jobs in the background *only* if they're non-zero, and we can style them with a high degree of freedom.
-It does a similar trick with a string-indexed associative array, and only displays the hostname if the `$XDG_SESSION_TYPE` is `"tty"` (which happens in `ssh` or `sudo` sessions). It dynamically displays the `$SUDO_USER` if that is available.
+It does a similar trick with a string-indexed associative array, and only displays the hostname if the `$XDG_SESSION_TYPE` is `"tty"` (which happens in `ssh` or `sudo` sessions). It dynamically displays the `$SUDO_USER` if that is available. If the system doesn't have the freedesktop XDG variable set, we try to set it to `"tty"` and then override that by trying to include any evidence of GUI desktop environment variables. This ends up doing some double-default nesting via the `_session` array.
What this means is that on your local desktop system, when you log in, your prompt is merely:
