$ python sqlmap.py -u "http://192.168.21.128/sqlmap/mysql/" --batch --crawl=3
[...]
[xx:xx:53] [INFO] starting crawler
[xx:xx:53] [INFO] searching for links with depth 1
[xx:xx:53] [WARNING] running in a single-thread mode. This could take a while
[xx:xx:53] [INFO] searching for links with depth 2
[xx:xx:54] [INFO] heuristics detected web page charset 'ascii'
[xx:xx:00] [INFO] 42/56 links visited (75%)
[...]