contrib: bash: completion.bash: add Bash completion for options

Makefile

@@ -27,6 +27,7 @@ BINDIR     = $(PREFIX)/bin
 DOCDIR      = $(PREFIX)/share/doc/$(PN)
 SCRIPTDIR   = $(PREFIX)/share/$(PN)/scripts
 SYSTEMDDIR  = $(PREFIX)/lib/systemd/system
+BASHCOMPDIR = $(PREFIX)/share/bash-completion/completions
 MAN1DIR     = $(PREFIX)/share/man/man1
 MAN5DIR     = $(PREFIX)/share/man/man5
 
@@ -42,12 +43,13 @@ replace_vars = sed \
 	-e "s|@DOCDIR@|$(DOCDIR)|g" \
 	-e "s|@SCRIPTDIR@|$(SCRIPTDIR)|g" \
 	-e "s|@SYSTEMDDIR@|$(SYSTEMDDIR)|g" \
+	-e "s|@BASHCOMPDIR@|$(BASHCOMPDIR)|g" \
 	-e "s|@MAN1DIR@|$(MAN1DIR)|g" \
 	-e "s|@MAN5DIR@|$(MAN5DIR)|g"
 
 all: man
 
-install: install-bin install-bin-links install-etc install-systemd install-share install-man install-doc
+install: install-bin install-bin-links install-etc install-completion install-systemd install-share install-man install-doc
 
 install-bin:
 	@echo 'installing binary...'
@@ -65,6 +67,11 @@ install-etc:
 	install -d -m 755 "$(DESTDIR)$(CONFDIR)/btrbk"
 	install -p -m 644 $(CONFIGS) "$(DESTDIR)$(CONFDIR)/btrbk"
 
+install-completion:
+	@echo 'installing bash completion...'
+	install -d -m 755 "$(DESTDIR)$(BASHCOMPDIR)"
+	install -p -m 644 contrib/bash/completion.bash "$(DESTDIR)$(BASHCOMPDIR)/$(BIN)"
+
 install-systemd:
 	@echo 'installing systemd service units...'
 	install -d -m 755 "$(DESTDIR)$(SYSTEMDDIR)"

contrib/bash/completion.bash

@@ -0,0 +1,14 @@
+_btrbk()
+{
+  local cur prev words cword split
+  _init_completion -s || return
+
+  $split && return
+
+  if [[ $cur == -* ]]; then
+    COMPREPLY=($(compgen -W '$(_parse_help "$1")' -- "$cur"))
+    [[ $COMPREPLY == *= ]] && compopt -o nospace
+  fi
+} && complete -F _btrbk btrbk
+
+# ex: filetype=bash