gotime

gistfile1.sh

# Step 1. Put some commented-out entries in your /etc/hosts file for sites you 
# want to block while you're working, with a comment/hashtag of gotime, like 
# this:

#127.0.0.1 reddit.com #gotime
#127.0.0.1 www.facebook.com #gotime

# Step 2. Add these lines to your shell's rc file:

alias gotime="sudo perl -pi -e 's/#([^\n]+)#gotime/\$1#gotime/g' /etc/hosts"
alias timetogo="sudo perl -pi -e 's/([^\n]+)#gotime/#\$1#gotime/g' /etc/hosts"

# Step 3. Re-source your rc file, or start a new shell

source .bashrc

# Step 4. When you want to get work done, use "gotime" to block those sites
# you specified above. Use "timetogo" to unblock them. You'll probably need to
# enter your password.

gotime

# Step 5. Be more productive! After unblocking a site, you may need to flush
# your DNS cache. In OS X, that's 'dscacheutil -flushcache'