problem using a pipe to grep

ShellBeginner · #1 (**permalink**) 05-31-2009

Hello !

I want to process a text file in order to extract desired data using sed and grep... Now I am facing a problem piping to grep... nothing happens..
The text consists of blocks of 3 lines that may (or not) contain the Desired data.

Quote:

line11 blabla1
line12 blabla2..
line13 blabla3..
line21 blabla1.. DesiredInfo
line22 blabla2..
line23 blabla3..
line31 blabla1.. DesiredInfo
line32 blabla2..
line33 blabla3..
etc.

the desired data is on each 2 first lines of some 'blocks'.. so I started by using the following so as to join the desired 2 lines in 1 (and skip the 3rd) in order to use it after with grep/sed :

Code:

#!/bin/bash
#script.sh
(while read line;
do
    read line2;
    read line3;
    echo $line $line2;
done)

Now I want to select only the lines containing the "DesiredInfo", for that I thought simply of adding a pipe to grep after the preceding code:

Code:

| grep DesiredInfo

but.. it doesn't work like that...(nothing happens) so I thought of putting directly in the shell prompt instead of the script:

Quote:

bash script.sh < directory/file.txt | grep DesiredInfo

but then again, nothing happens...
Is there a problem with piping to 'grep' ?

thank you for your precious help !!

TonyFullerMalv · #2 (**permalink**) 05-31-2009

You have an open bracket "(" but no close bracket anywhere, you need to drop the open bracket as a first step to getting this working.

ShellBeginner · #3 (**permalink**) 05-31-2009

Thank you for answering me...

Actually I found that the 'problem' was that it took so much time (50 sec.) to display the result that I thought it was not working... but in fact it was ok

Thank you anyway !!

vidyadhar85 · #4 (**permalink**) 05-31-2009

then try using simple awk instead of while loop

Code:

awk '{var=$0}{getline}{var2=$0}{getline}{var3=$0}{print var" "var2}' filename|grep DesiredInfo

ShellBeginner · #5 (**permalink**) 05-31-2009

Quote:

Originally Posted by vidyadhar85

then try using simple awk instead of while loop

Code:

awk '{var=$0}{getline}{var2=$0}{getline}{var3=$0}{print var" "var2}' filename|grep DesiredInfo

Oh ! thank you ! really efficient with that !

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