How to run commands with pipe from text file?

Apostol · 03-11-2018, 03:37 AM

Hello,

I have standard loop

Code:

while read -r info; do
command $info
done < info

in info text file I have multiple commands each on line that I want to execute. When I used them in console they worked, but not with this loop. This is one of the commands in info file:

Code:

grep --line-buffered "title" dir/file.html | grep -Po '(?<=>)(.*)(?=<)'

It works with first grep, but not with second one. I found --line-buffered parameter, but didn't helped. Can somebody help me?

pan64 · 03-11-2018, 04:09 AM

Code:

eval $info

seems ok, but it is not really suggested.
command can only execute one command, and your example contained 2 commands (2 greps)

syg00 · 03-11-2018, 04:53 AM

If you are using PCRE, why do you need to pipe grep to grep ?.

Apostol · 03-11-2018, 05:52 AM

pan64
Thank you. Eval works perfectly.

syg00
Because first I need to find line from which I want to extract information.

pan64 · 03-11-2018, 09:55 AM

Quote:

Originally Posted by Apostol

Because first I need to find line from which I want to extract information.

This is not a reason to run two greps instead of only one. It will run faster, needs less resources and as you can see makes less difficulties too.
Most probably you can combine the two patters like:

Code:

grep -Po '(?<=title>)(.*)(?=<)'

or something similar.

A final comment: parsing a html in shell is not an easy job, probably a real html/xml parser would be better.