Question: I'd like to test the speed of a bash script and a Python script. How would I get the time it took to run them?

Answer: 
If you're on Linux (or another UN\*X), try [`time`](http://unixhelp.ed.ac.uk/CGI/man-cgi?time):

> 
> The time command runs the specified program command with the given
>  arguments. When command finishes, time writes a message to standard
>  error giving timing statistics about this program run. These statis-
>  tics consist of (i) the elapsed real time between invocation and termi-
>  nation, (ii) the user CPU time (the sum of the tms\_utime and tms\_cutime
>  values in a struct tms as returned by times(2)), and (iii) the system
>  CPU time (the sum of the tms\_stime and tms\_cstime values in a struct
>  tms as returned by times(2)).
> 
> 
> 

Note that you need to eliminate outer effects - e.g. other processes using the same resources can skew the measurement.
At the beginning of each script output the start time and at the end of each script output the end time. Subtract the times and compare. Or use the time command if it is available as others have answered.