Since you're starting the mining proxy from a cron job, the output of the job is discarded, since cron jobs are normally automated tasks. To interact with the proxy after it has started, you can run the proxy in a "screen" session using the screen command, allowing you to view the output while it runs. To do so, amend your cron job so that it looks like:

15 7 * * * /usr/bin/screen -dmS ANameForTheScreenSession commandIwantToRunInScreen

where:

• /usr/bin/screen is the location of the screen command; make sure you already have screen installed by running `which screen` which should return the location, or install it by using `apt-get install screen`.
• ANameForTheScreenSession is a name to identify the session
• commandIwantToRunInScreen is the command you used to start the mining proxy

If all goes well, after the cron job starts again, you should be able to view the proxy by running `screen -r ANameForTheScreenSession`. Once in the screen session, you can disconnect from the session by pressing Ctrl-A + D; the proxy will continue to run in the background.

References:
http://www.linuxquestions.org/questions/linux-software-2/running-screen-in-a-cron-job-349153/
http://ss64.com/bash/screen.html

EDIT: If your proxy cron job is running as root, then the screen session will also run as root. If this is the case, simply prepend "sudo" to the command used to view the session.