sh compatibility in minor scripts

.scripts/opout

@@ -1,13 +1,11 @@
-#!/bin/bash
+#!/bin/sh
 # opout: "open output": A general handler for opening a file's intended output.
 # I find this useful especially running from vim.
 
-filename=$(readlink -f "$1")
-ext="${filename##*.}"
-filename="${filename%.*}"
+basename="${1%.*}"
 
-case "$ext" in
-	tex|md|rmd) setsid zathura "$filename".pdf & ;;
-	html) setsid $TRUEBROWSER --new-window "$filename".html & ;;
-	sent) setsid sent "$1" & ;;
+case "$1" in
+	*.tex|*.md|*.rmd) setsid zathura "$basename".pdf & ;;
+	*.html) setsid "$TRUEBROWSER" --new-window "$basename".html & ;;
+	*.sent) setsid sent "$1" & ;;
 esac