sed portable?

bin/mw

@@ -182,7 +182,7 @@ formatShortcut() { \
 
 tryconnect() { mkdir -p "$maildir/$title"
 	if mailboxes="$(mbsync -l "$title" | sed 's/\//./')" >/dev/null 2>&1 && [ -n "$mailboxes" ]; then
-		[ "$accounttype" = "online" ] && sed -i "/IMAPStore $title-remote$/,/# End profile/d" "$mbsyncrc"
+		[ "$accounttype" = "online" ] && sed -ibu "/IMAPStore $title-remote$/,/# End profile/d" "$mbsyncrc" ; rm -f "$mbsync"bu
 		printf "\033[32mMailboxes detected.\033[0m\\n"
 		echo "$mailboxes" | xargs -I {} mkdir -p "$maildir/$title/{}"
 		return 0
@@ -199,11 +199,11 @@ finalize() { \
 	record=$(echo "$boxes" | grep -i -m 1 sent | sed 's/=/+/g')
 	postponed=$(echo "$boxes" | grep -i -m 1 draft | sed 's/=/+/g')
 	trash=$(echo "$boxes" | grep -i -m 1 trash | sed 's/=/+/g')
-	sed -i "/^mailboxes\|^set record\|^set postponed\|^set trash\|^set spoolfile/d" "$accdir/$idnum-$title.muttrc"
+	sed -ibu "/^mailboxes\|^set record\|^set postponed\|^set trash\|^set spoolfile/d" "$accdir/$idnum-$title.muttrc" ; rm -f "$accdir/$idnum-$title.muttrcbu"
 	{ echo "set spoolfile = \"$spoolfile\""; echo "set record = \"$record\""; echo "set postponed = \"$postponed\""; echo "set trash = \"$trash\""; } >> "$accdir/$idnum-$title.muttrc"
 	echo "mailboxes =$title ===================== $(echo "$boxes" | sed -e "s/^\|$/\"/g" | tr "\n" " ")" >> "$accdir/$idnum-$title.muttrc"
 	printf "Setting up your keyboard shortcuts for jumping between mailboxes...\\n"
-	sed -i "/# mw-autogenerated/d" "$accdir/$idnum-$title.muttrc"
+	sed -ibu "/# mw-autogenerated/d" "$accdir/$idnum-$title.muttrc" ; rm -f "$accdir/$idnum-$title.muttrcbu"
 	echo "$boxes" | grep -i inbox | head -n 1 | formatShortcut i inbox
 	echo "$boxes" | grep -i sent | head -n 1 | formatShortcut s sent
 	echo "$boxes" | grep -i draft | head -n 1 | formatShortcut d drafts
@@ -227,10 +227,10 @@ pick() { printf "Select an accounts to %s:\\n" "$1"
 	[ -z "$title" ] && printf "Invalid response." && return 1
 	return 0 ;}
 
-delete() { sed -i "/IMAPStore $title-remote$/,/# End profile/d" "$mbsyncrc"
+delete() { sed -ibu "/IMAPStore $title-remote$/,/# End profile/d" "$mbsyncrc" ; rm -rf "$mbsyncrc"bu
 	rm -rf "${cachedir:?}/${title:?}" "$accdir/"[1-9]"-$title.muttrc"
-	sed -i "/[0-9]-$title.muttrc/d" "$muttrc"
-	sed -i "/account $title/,/^\(\s*$\|account\)/d" "$HOME/.config/msmtp/config"
+	sed -ibu "/[0-9]-$title.muttrc/d" "$muttrc" ; rm -f "$muttrc"bu
+	sed -ibu "/account $title/,/^\(\s*$\|account\)/d" "$HOME/.config/msmtp/config"; rm -f "$HOME/.config/msmtp/configbu"
 	}
 
 choosecron() { ! pgrep -x cron\|crond >/dev/null && echo "No cron manager running. Install/enable one and then select this option again." && return 1
@@ -266,7 +266,7 @@ asktype() { while : ; do
 purge() { confirm "delete all account data" || exit
 	rm -rf "$mbsyncrc" "$accdir" "$HOME/.config/msmtp" "$cachedir"
 	echo "All configs and account settings have been purged."
-	sed -i "/\# mw-autogenerated/d" "$muttrc"
+	sed -ibu "/\# mw-autogenerated/d" "$muttrc" ; rm -f "$muttrc"bu
 }
 
 notmuchauto() { \