Add bash completion script

doc/src/guide/getting_started.asciidoc

@@ -38,6 +38,31 @@ Alternatively, just https://erlang.mk/erlang.mk[click on this link].
 
 Make sure you put the file inside the folder we created previously.
 
+==== Bash completion
+
+If your preferred shell is Bash, a completion script is available.
+In order to install it, use the following commands:
+
+[source,bash]
+----
+$ mkdir ~/.bash_completion.d/
+$ cd ~/.bash_completion.d/
+$ wget -O erlang_mk https://raw.githubusercontent.com/ninenines/erlang.mk/master/etc/bash_completion
+----
+
+Then edit the file `~/.bash_completion` and add:
+
+[source,bash]
+----
+for bcfile in ~/.bash_completion.d/* ; do
+    . $bcfile
+done
+----
+
+Note that Make's legacy Bash completion will be overwritten.
+If you need legacy completion for other C projects, consider sourcing
+Erlang.mk's Bash completion only in your Erlang project directory instead.
+
 === Getting started with OTP applications
 
 An OTP application is an Erlang application that has a supervision

etc/bash_completion

@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+# Copyright (c) 2020, Eric Pailleau <crownedgrouse@wanadoo.fr>
+# This file is part of erlang.mk and subject to the terms of the ISC License.
+# Date: April 12th 2020
+# Bash completion for Erlang.mk
+
+_erlang_mk()
+{
+    local cur prev words cword
+    _init_completion || return
+
+    T=$(make list-templates | cut -d ':' -f 2-)
+    TP=$(echo -n $T | cut -d '_' -f 1 | tr ' ' '|')
+    TPP=$(echo -n $T | tr ' ' '|')
+    case $prev in
+        make)
+            COMPREPLY=( $(compgen -W "all app deps fetch-deps list-deps search rel docs install-docs check tests clean distclean help erlang-mk bootstrap bootstrap-lib bootstrap-rel new-app new-lib new new list-templates ct plt dialyze escript eunit shell sphinx xref cover-report all.coverdata" -- "$cur") )
+            ;;
+        search)
+            COMPREPLY=( $(compgen -W 'q=' -- "$cur") ) && compopt -o nospace
+            ;;
+        new-app|new-lib)
+            COMPREPLY=( $(compgen -W 'in=' -- "$cur") ) && compopt -o nospace
+            ;;
+        new)
+            COMPREPLY=( $(compgen -W 't=' -- "$cur") ) && compopt -o nospace
+            ;;
+        =)
+            if [[ ${words[$cword - 2]} == "in" ]]; then
+                COMPREPLY=( $(compgen -W "$(ls apps 2>/dev/null)" -- "$cur") ) && compopt -o nospace
+            else
+                if [[ ${words[$cword - 2]} == "t" ]]; then
+                    COMPREPLY=( $(compgen -W "$T" -- "$cur") ) && compopt -o nospace
+                fi
+            fi
+            ;;
+        $TP)
+            COMPREPLY=( $(compgen -W "$T" -- "$cur") ) && compopt -o nospace
+            ;;
+        $TPP)
+            COMPREPLY=( $(compgen -W 'n=' -- "$cur") ) && compopt -o nospace
+            ;;
+        *)
+        if [[ "$prev" == "in" && "$cur" == '=' ]]; then
+            test -d apps && echo  1>&2
+            test -d apps && echo $(ls apps 2>/dev/null)
+                   COMPREPLY=( $(compgen -W "$(ls apps 2>/dev/null )" -- "$cur") ) && compopt -o nospace
+        fi
+        if [[ "$prev" == "t" && "$cur" == '=' ]]; then
+            echo  1>&2
+            echo $T 1>&2
+                COMPREPLY=( $(compgen -W "$T" -- "$cur") ) && compopt -o nospace
+        fi
+            if [[ $(echo "$T" | tr ' ' "\n" | grep "$prev") ]]; then
+                COMPREPLY=( $(compgen -W 'n=' -- "$cur") ) && compopt -o nospace
+            fi
+            if [[ ${words[$cword - 1]} == "n=" || ${words[$cword - 1]} == "n" ]]; then
+                COMPREPLY=( $(compgen -W 'in=' -- "$cur") ) && compopt -o nospace
+            fi
+            if [[ ${words[$cword - 3]} == "n" ]]; then
+                COMPREPLY=( $(compgen -W 'in=' -- "$cur") ) && compopt -o nospace
+            fi
+            ;;
+    esac
+
+    case $cur in
+        all|bootstrap|list|list-|new|new-)
+            echo 1>&2
+            make help | grep "^  $cur" 1>&2
+            return
+            ;;
+    esac
+} &&
+complete -F _erlang_mk make