cqfd: add shell command

This adds the shell command to run a $SHELL command from within the
container.

It is a convenient frontend to "cqfd run bash", and it the respects the
arguments:

	$ cqfd shell -c 'echo "0=\"$0\"" "*=\"$*\"" "#=\"$#\""' zero one two three
	0="zero" *="one two three" #="3"

Note: The command shell does not run the command= set in the file
.cqfdrc.

bash-completion

@@ -63,6 +63,19 @@ _cqfd() {
 
 		COMPREPLY=( $(compgen -c -W "-c" -- "$cur") )
 		return
+	elif [[ "$arg" == shell ]]; then
+		for (( i=1; i <= cword; i++ )); do
+			if [[ ${words[i]} == shell ]]; then
+				((i++))
+				break
+			fi
+		done
+
+		COMP_WORDS=("${SHELL:-/bin/sh}" "${COMP_WORDS[@]:$i}" "$cur")
+		COMP_LINE="${COMP_WORDS[*]}"
+		COMP_POINT="${#COMP_LINE}"
+		_command_offset 0
+		return
 	fi
 
 	local opts="-C -d -f -b -q -V --version -h --help"
@@ -71,7 +84,7 @@ _cqfd() {
 		return
 	fi
 
-	local cmds="init flavors run release version help"
+	local cmds="init flavors run release shell version help"
 	COMPREPLY=( $(compgen -W "$cmds $opts" -- "$cur") )
 } &&
 complete -F _cqfd cqfd

cqfd

@@ -46,6 +46,7 @@ Commands:
     flavors              List flavors from config file to stdout.
     run [cmdstring]      Run argument(s) inside build container.
     release [cmdstring]  Run argument(s) and release software.
+    shell [shargs]       Run shell command inside build container.
     help                 Show this help text.
 
     By default, the 'run' command is assumed, with the default
@@ -517,6 +518,16 @@ while [ $# -gt 0 ]; do
 		build_cmd_alt="$*"
 		break
 		;;
+	shell)
+		shift
+		config_load $flavor
+		command_string="${SHELL:-/bin/sh}"
+		if [ "$#" -ne 0 ]; then
+			command_string+=" ${@@Q}"
+		fi
+		docker_run "$command_string"
+		exit
+		;;
 	?*)
 		echo "Unknown command: $1"
 		usage