finding an email address inside an mbox file
Assuming the mbox has been saved into a file called thefile.txt:
grep -E -o "\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,6}\b" thefile.txt
Pause a program which is using too much CPU
Sometimes your battery is running low and you need to pause a program without quitting it or force-quitting it, so that you can preserve battery but not lose the job that the program is doing. To do this, Step 1. open a terminal Step 2. type: ps ax | grep -i "<program name>" so for example, if it's photoshop you need to pause, replace "<program name>" with "photoshop" Step 3. Next to the results on the far left you'll see a number, usually with 5 digits. E.g. 12345. Step 4. Type: kill -STOP 12345 where 12345 are the numbers obtained in Step 2-3. Step 5. When you want to resume the program, type kill -CONT 12345 It should then continue to operate or run as usual without problems.