Bash – sed: how to insert a comment at the beginning of a matching line

You are attempting to edit in place (-i option) the STDIN.

Remove -i option, it is useless.

Note:

You can speed up the command a lot avoiding the second grep, excluding at the root the unnecessary directories

Try

grep -lIR --exclude-dir=.svn "dlclose" . | xargs sed -i bak 's/.*dlclose.*/\/\/&/g'  

or

for f in $(grep -lIR --exclude-dir=.svn "dlclose" .)
do
   sed -i bak 's/.*dlclose.*/\/\/&/g' $f
done

Its failing because sudo is prompting for a password. Since there's no TTY open, its just waiting for you to enter one--or may, in fact, be instantly failing. If you're running this as root, you don't need to launch it as sudo.

However, what you likely want to do is alter tornadoDeploy.py to daemonize itself--that is, to detach itself, so that its not running with an open session. The python-daemonize library provides easy tools to allow you to do this. This eliminates having to deal with screen, while still allowing you to daemonize the process.