Very old question but I have a solution that does not require the -s flag, and does not require temperamental string operations.
A good solution might be to exploit the fact that an unauthenticated sudo call hangs for a long time.
sudo date will return pretty much instantly if authenticated, but will hang if not.
The timeout command is placed before another command to limit how long it takes to execute, and exits with code 124 if it cuts the execution of the inner command short. You can check the exit code of the last command with echo $?
With that in mind...
timeout .1s sudo dateEXITCODE=$?Now test if $EXITCODE is 127 or not and you have your answer :)
