Add bash-completion

.bash-completion

@@ -0,0 +1,11 @@
+_ghcup()
+{
+	local cur
+	COMPREPLY=()
+	cur="${COMP_WORDS[COMP_CWORD]}"
+	if [[ ${#COMP_WORDS[*]} -le 2 ]]; then
+		COMPREPLY=($(compgen -W "$(ghcup --list-commands)" -- $cur))
+	fi
+	return 0
+} &&
+complete -F _ghcup ghcup

README.md

@@ -68,6 +68,12 @@ handles your haskell packages and can demand that [a specific version](https://c
 For man pages to work you need [man-db](http://man-db.nongnu.org/) as your `man` provider, then issue `man ghc`. Manpages only work for the currently set ghc.
 `MANPATH` may be required to be unset.
 
+### Bash-completion
+
+Depending on your distro and setup, install `.bash-completion` from this repo
+as e.g. `/etc/bash_completion.d/ghcup` and make sure your bashrc sources the
+startup script (`/usr/share/bash-completion/bash_completion` on some distros).
+
 ## Design goals
 
 1. simplicity

app/ghcup/Main.hs

@@ -654,6 +654,12 @@ main = do
         <> help "Show the numeric version (for use in scripts)"
         <> hidden
         )
+  let listCommands = infoOption
+        "install set rm install-cabal list upgrade compile debug-info tool-requirements changelog"
+        (  long "list-commands"
+        <> help "List available commands for shell completion"
+        <> internal
+        )
 
   let main_footer = [i|Discussion:
   ghcup installs the Glasgow Haskell Compiler from the official
@@ -668,7 +674,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
 
   customExecParser
       (prefs showHelpOnError)
-      (info (opts <**> helper <**> versionHelp <**> numericVersionHelp)
+      (info (opts <**> helper <**> versionHelp <**> numericVersionHelp <**> listCommands)
             (footerDoc (Just $ text main_footer))
       )
     >>= \opt@Options {..} -> do