rework bash scripts to be completely, or mostly POSIX-compliant

.bashrc

@@ -5,17 +5,18 @@
 # sourced upon launch of an interactive shell, which isn't a login shell has been executed
 #
 
-# If not running interactively, don't do anything
-[[ $- != *i* ]] && return
-[[ -z "${PS1-}" ]] && return
+case $- in
+*i*) return ;;
+esac
+[ -z "${PS1-}" ] && return
 
 # lazy loading of ssh agents
 _lazy_ssh() {
-	if [[ -z $SSH_AUTH_SOCK ]]; then
-		eval "$(ssh-agent -s)" &>/dev/null
-		ssh-add "$HOME/.ssh/github" &>/dev/null
-		ssh-add "$HOME/.ssh/gitea" &>/dev/null
-		ssh-add "$HOME/.ssh/admin@homeserver" &>/dev/null
+	if [ -z "$SSH_AUTH_SOCK" ]; then
+		eval "$(ssh-agent -s)" >/dev/null
+		ssh-add "$HOME/.ssh/github" >/dev/null
+		ssh-add "$HOME/.ssh/gitea" >/dev/null
+		ssh-add "$HOME/.ssh/admin@homeserver" >/dev/null
 	fi
 }
 # aliases so the function is called beforehand
@@ -73,4 +74,4 @@ shopt -s globstar     # enable globstar (**/*)
 [ -f "$HOME/.bash_aliases" ] && . .bash_aliases
 
 # cute lil hyfetch :3
-[[ $TERM == "xterm-kitty" ]] && fastfetch
+[ "$TERM" == "xterm-kitty" ] && fastfetch