Bash completion aliases (#638)

* alias support with bash completions

* add cmdname to rootcmdname

* remove print statement

* add documentation for bash alias

bash_completions.go

@@ -228,7 +228,7 @@ __%[1]s_handle_command()
         next_command="_${last_command}_${words[c]//:/__}"
     else
         if [[ $c -eq 0 ]]; then
-            next_command="_$(basename "${words[c]//:/__}")"
+            next_command="_%[1]s_root_command"
         else
             next_command="_${words[c]//:/__}"
         fi
@@ -249,7 +249,7 @@ __%[1]s_handle_word()
         __%[1]s_handle_flag
     elif __%[1]s_contains_word "${words[c]}" "${commands[@]}"; then
         __%[1]s_handle_command
-    elif [[ $c -eq 0 ]] && __%[1]s_contains_word "$(basename "${words[c]}")" "${commands[@]}"; then
+    elif [[ $c -eq 0 ]]; then
         __%[1]s_handle_command
     else
         __%[1]s_handle_noun
@@ -461,7 +461,13 @@ func gen(buf *bytes.Buffer, cmd *Command) {
 	commandName := cmd.CommandPath()
 	commandName = strings.Replace(commandName, " ", "_", -1)
 	commandName = strings.Replace(commandName, ":", "__", -1)
+
+	if cmd.Root() == cmd {
+		buf.WriteString(fmt.Sprintf("_%s_root_command()\n{\n", commandName))
+	} else {
 		buf.WriteString(fmt.Sprintf("_%s()\n{\n", commandName))
+	}
+
 	buf.WriteString(fmt.Sprintf("    last_command=%q\n", commandName))
 	writeCommands(buf, cmd)
 	writeFlags(buf, cmd)

bash_completions.md

@@ -204,3 +204,17 @@ __kubectl_get_namespaces()
     fi
 }
 ```
+# Using bash aliases for commands
+
+You can also configure the `bash aliases` for the commands and they will also support completions.
+
+```bash
+alias aliasname=origcommand
+complete -o default -F __start_origcommand aliasname
+
+# and now when you run `aliasname` completion will make
+# suggestions as it did for `origcommand`.
+
+$) aliasname <tab><tab>
+completion     firstcommand   secondcommand
+```