I answered a similar question [here](http://gis.stackexchange.com/a/187416/70317)

> You can download and clip a portion of the SRTM 30m DEM with one
> command with the
> [elevation](http://elevation.bopen.eu/en/stable/quickstart.html)
> Python command line tool.
> 
> Install it and perform the self check with:
> 
>     $ pip install elevation
> 
> Check if you have all the dependencies installed (mainly GDAL tools):
> 
>     $ eio selfcheck
> 
> Download and clip a portion of the SRTM 30m DEM giving bounding box as
> WGS84 coordinates:
> 
>     $ eio clip -o Rome-DEM.tif --bounds 12.35 41.8 12.65 42