don't rely on base32 being present

local/bin/sspt

@@ -31,7 +31,11 @@ escape_string() {
 }
 export -f escape_string
 temp_filename() {
-    echo "/tmp/sspt-$(head -c 4 /dev/urandom | base32)"
+    if command -v base32 >/dev/null 2>&1; then
+        echo "/tmp/sspt-$(head -c 4 /dev/urandom | base32)"
+    else
+        echo "/tmp/sspt-$(head -c 4 /dev/urandom | hexdump | head -1 | tr -d ' ')"
+    fi
 }
 export -f temp_filename
 file_exists_glob() {