From e3f97d6c12e6e311b155ce24ce586717b1abc18b Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Wed, 25 Jan 2017 14:31:32 +1300
Subject: Show prompt prefix if a shell is exotic

That is, include e.g. "ksh:" as a prefix to the prompt if the user
appears to have Bash or Zsh (or anything else) as their login shell.

This is probably imperfect, but it's a start.
---
 README.markdown           |  3 +++
 bash/bashrc.d/prompt.bash |  6 ++++++
 ksh/kshrc.d/prompt.ksh    | 14 ++++++++++++++
 zsh/zshrc.d/prompt.zsh    |  6 ++++++
 4 files changed, 29 insertions(+)

diff --git a/README.markdown b/README.markdown
index 9c956d51..70234ed8 100644
--- a/README.markdown
+++ b/README.markdown
@@ -147,6 +147,9 @@ include these elements in this order:
 You can set `PROMPT_COLOR`, `PROMPT_PREFIX`, and `PROMPT_SUFFIX` too, which all
 do about what you'd expect.
 
+If you start up Bash, Ksh, or Zsh and it detects that it's not normally your
+`$SHELL`, the prompt will display an appropriate prefix.
+
 This is all managed within the `prompt` function. There's some mildly hacky
 logic on `tput` codes included such that it should work correctly for most
 common terminals using both `termcap(5)` and `terminfo(5)`, including \*BSD
diff --git a/bash/bashrc.d/prompt.bash b/bash/bashrc.d/prompt.bash
index b22f118f..2bd70c2f 100644
--- a/bash/bashrc.d/prompt.bash
+++ b/bash/bashrc.d/prompt.bash
@@ -22,6 +22,12 @@ prompt() {
             # Add sub-commands; VCS, job, and return status checks
             PS1=$PS1'$(ret=$?;prompt vcs;prompt job;prompt ret)'
 
+            # Add a helpful prefix if this shell appears to be exotic
+            case ${SHELL##*/} in
+                (bash) ;;
+                (*) PS1=bash:$PS1 ;;
+            esac
+
             # Add prefix and suffix
             PS1='${PROMPT_PREFIX}'$PS1'${PROMPT_SUFFIX}'
 
diff --git a/ksh/kshrc.d/prompt.ksh b/ksh/kshrc.d/prompt.ksh
index bf77f626..09c7de6e 100644
--- a/ksh/kshrc.d/prompt.ksh
+++ b/ksh/kshrc.d/prompt.ksh
@@ -22,6 +22,20 @@ function prompt {
             # count, and previous command return value
             PS1=$PS1'$(ret=$?;jobc=$(jobs -p|sed -n '\''$='\'');prompt pwd;prompt vcs;prompt job;prompt ret;:)'
 
+            # Add a helpful prefix if this shell appears to be exotic
+            typeset ksh
+            case $KSH_VERSION in
+                (*'93'*) ksh=ksh93 ;;
+                (*'PD KSH'*) ksh=pdksh ;;
+                (*'MIRBSD KSH'*) ksh=mksh ;;
+            esac
+            case ${SHELL##*/} in
+                ('') ;;
+                (ksh) ;;
+                ("$ksh") ;;
+                (*) PS1=$ksh:$PS1 ;;
+            esac
+
             # Add prefix and suffix
             PS1='${PROMPT_PREFIX}'$PS1'${PROMPT_SUFFIX}'
 
diff --git a/zsh/zshrc.d/prompt.zsh b/zsh/zshrc.d/prompt.zsh
index cfac7ffd..f374dbec 100644
--- a/zsh/zshrc.d/prompt.zsh
+++ b/zsh/zshrc.d/prompt.zsh
@@ -18,6 +18,12 @@ prompt() {
             # Add sub-commands; VCS, job, and return status checks
             PS1=$PS1'$(ret=$?;prompt vcs;prompt job;prompt ret)'
 
+            # Add a helpful prefix if this shell appears to be exotic
+            case ${SHELL##*/} in
+                (zsh) ;;
+                (*) PS1=zsh:$PS1 ;;
+            esac
+
             # Add prefix and suffix
             PS1='${PROMPT_PREFIX}'$PS1'${PROMPT_SUFFIX}'
 
-- 
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