Add a simple command-line "authenticator app" for testing

tests/lib/totp_cli.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+. $(dirname "0")/totp.sh || exit 1
+
+while [ $# -gt 0 ]; do
+    arg="$1"
+    shift
+    if [ "$arg" == "token" ]; then
+        # our "authenticator app"
+        #
+        # get the current token for the secret supplied or if no
+        # secret given on the command line, from the saved secret in
+        # /tmp/totp_secret.txt
+        #
+        secret_file="/tmp/totp_secret.txt"
+        
+        if [ $# -gt 0 ]; then
+            recalled=false
+            secret="$1"
+            shift
+            
+        else
+            recalled=true
+            echo "Re-using last secret from $secret_file" 1>&2
+            secret="$(cat $secret_file)"
+            if [ $? -ne 0 ]; then
+                exit 1
+            fi
+        fi
+        
+        totp_current_token "$secret"
+        code=$?
+        if [ $code -ne 0 ]; then
+            exit 1
+            
+        elif ! $recalled; then
+            echo "Storing secret in $secret_file" 1>&2
+            touch "$secret_file" || exit 2
+            chmod 600 "$secret_file" || exit 3
+            echo -n "$secret" > "$secret_file" || exit 4
+        fi
+
+        exit 0
+    fi
+done
+