Can not assign variable to output of sed

protocol · 10-24-2011, 03:27 PM

Hello all

Why is the following line not printing anything on the screen:

tail -f /var/log/mail.log | var=`sed -nr 's/.*to=<([^>]*)>.*/\1/p'` echo $var;

Note: This thread related to this one: http://www.linuxquestions.org/questi...e-line-909845/

Please assist.

acid_kewpie · 10-24-2011, 03:59 PM

it just kinda makes no sense at all, in many ways, I'm afraid. what do you expect it to do? the echo command is being tagged onto the end of the assignment execution, you're following the tail, that command will never finish... drop the idea of assigning the sed output to anything, i'm sure your output can easily be made to fall out the end, do you now just want a grep after it maybe?

protocol · 10-24-2011, 04:02 PM

Hello Chris.

What i want, is to take sed's output (an email address) and "post" that address to an external script that will -in turn- insert that email address to a database. Sorry for my poor bash skills, i just feel certain that it can be done somehow. No?

Regards, Panos.

acid_kewpie · 10-24-2011, 04:15 PM

so why not just do

tail -f /var/log/mail.log | grep to= | sed -nr 's/.*to=<([^>]*)>.*/\1/p'

protocol · 10-24-2011, 04:27 PM

Quote:

Originally Posted by acid_kewpie

so why not just do

tail -f /var/log/mail.log | grep to= | sed -nr 's/.*to=<([^>]*)>.*/\1/p'

This also prints email addresses on the screen (quite natural, since you made it ..

) and still leaves me wondering how would i go about with "posting" the result of grep to an external script. Again, sorry for my poor knowledge of bash scripting (i am getting better by the minute, hanging out with you people..).

Panos

acid_kewpie · 10-24-2011, 04:36 PM

well you'd probably just pipe it again onto yet another command. Note again though, as you're tail -f'ing this, the command will never complete, so you need to work out how to deal with that.