create: Use $XDG_CACHE_HOME, keep cache files in $HOME/.cache/distrob…

…ox by default (#1082)

* Read $XDG_CACHE_HOME, fall back to $HOME/.cache

This allows configuring where the cache dir is located, according to
XDG Base Directory Specification
(https://specifications.freedesktop.org/basedir-spec/latest/ar01s03.html).

* Change default cache dir from ~/.cache to ~/.cache/distrobox

I think it's a good idea to keep the cache files grouped under a
directory, indicating ownership, and this is the most common thing to do
in GNU/Linux distros.

distrobox-create

@@ -94,6 +94,8 @@ distrobox_hostexec_path="$(cd "$(dirname "${0}")" && pwd)/distrobox-host-exec"
 verbose=0
 version="1.6.0.1"
 
+app_cache_dir=${XDG_CACHE_HOME:-"${HOME}/.cache"}/distrobox
+
 # Source configuration files, this is done in an hierarchy so local files have
 # priority over system defaults
 # leave priority to environment variables.
@@ -210,9 +212,9 @@ EOF
 # Outputs:
 #   print usage with examples.
 show_compatibility() {
-	if [ ! -e "${HOME}/.cache/distrobox-compatibility-${version}" ] ||
-		[ ! -s "${HOME}/.cache/distrobox-compatibility-${version}" ]; then
-		mkdir -p "${HOME}/.cache"
+	if [ ! -e "${app_cache_dir}/distrobox-compatibility-${version}" ] ||
+		[ ! -s "${app_cache_dir}/distrobox-compatibility-${version}" ]; then
+		mkdir -p "${app_cache_dir}"
 
 		# If we don't have a cache file, we need connectivity. Ensure we have
 		# one and return error if not.
@@ -228,9 +230,9 @@ show_compatibility() {
 			cut -d '|' -f 4 |
 			sed 's|<br>|\n|g' |
 			tr -d ' ' |
-			sort -u > "${HOME}/.cache/distrobox-compatibility-${version}"
+			sort -u > "${app_cache_dir}/distrobox-compatibility-${version}"
 	fi
-	cat "${HOME}/.cache/distrobox-compatibility-${version}"
+	cat "${app_cache_dir}/distrobox-compatibility-${version}"
 }
 
 # Parse arguments

distrobox-enter

@@ -28,10 +28,12 @@
 #	DBX_SKIP_WORKDIR
 #	DBX_SUDO_PROGRAM
 
+app_cache_dir=${XDG_CACHE_HOME:-"${HOME}/.cache"}/distrobox
+
 trap cleanup TERM INT HUP EXIT
 
 cleanup() {
-	rm -f "${HOME}/.cache/.${container_name}.fifo"
+	rm -f "${app_cache_dir}/.${container_name}.fifo"
 	if [ -n "${logs_pid:-}" ]; then
 		kill "${logs_pid:-}" 2> /dev/null || :
 	fi
@@ -527,14 +529,14 @@ if [ "${container_status}" != "running" ]; then
 	fi
 
 	printf >&2 "%-40s\t" "Starting container..."
-	mkdir -p "${HOME}/.cache/"
-	rm -f "${HOME}/.cache/.${container_name}.fifo"
-	mkfifo "${HOME}/.cache/.${container_name}.fifo"
+	mkdir -p "${app_cache_dir}"
+	rm -f "${app_cache_dir}/.${container_name}.fifo"
+	mkfifo "${app_cache_dir}/.${container_name}.fifo"
 	while true; do
 		# save starting loop timestamp in temp variable, we'll use it
 		# after to let logs command minimize possible holes
 		${container_manager} logs -f "${container_name}" 2> /dev/null \
-			> "${HOME}/.cache/.${container_name}.fifo" &
+			> "${app_cache_dir}/.${container_name}.fifo" &
 		logs_pid="$!"
 
 		# read logs from log_timestamp to now, line by line
@@ -559,10 +561,10 @@ if [ "${container_status}" != "running" ]; then
 					;;
 				*) ;;
 			esac
-		done < "${HOME}/.cache/.${container_name}.fifo"
+		done < "${app_cache_dir}/.${container_name}.fifo"
 	done
 	# cleanup fifo
-	rm -f "${HOME}/.cache/.${container_name}.fifo"
+	rm -f "${app_cache_dir}/.${container_name}.fifo"
 	printf >&2 "\nContainer Setup Complete!\n"
 fi