UNIX for Dummies Questions & Answers

Dear forum,

Please excuse my ignorance. I have looked through various forum posts and tried various solutions but have not been able to solve my problem.

File1.txt consist of a list of 100 names (one per line). File2.txt contains details for 1000 people (one per line), with the first field being the name and the other fields being the details

I would like to create a file that has all the lines from the File2.txt that correspond to each of the names from File1.txt.

I have been able to read in File1.txt with a loop and echo out the lines, but unable to perform a grep command successfully.

Here is how the files look like

Code:

#File 1.txt 
jane
peter
mary

#File2.txt
jane brownhair blueeyes
peter blackhair blueeyes
mary brownhair blackeyes

My script looks like this

Code:

while read line
do
grep "$line" File2.txt -n >> tmp.txt
echo $line
done < File1.txt

This printed out all the lines of the file but nothing was found in the tmp.txt file.
I have tried grepping each string eg "grep jane File2.txt" and that was successful, but when grep was used on the variable from the loop, it did not work.

I have also tried removing whitespaces from the files with the commands

Code:

awk '{gsub(/^[ \t]+|[ \t]+$/,"")};1'
awk '{$1=$1};1' bad1 > bad2

but it did not work

I tried doing var1=$(cat File1.txt) and using a for loop on $var1 but it did not work either.

Really appreciate any help.
Thanks a lot.

Beginner0302

Moderator's Comments:

Please use code tags <- click the link!

I would think this command would give you what you want:

Code:

grep -n -f file1.txt file2.txt

This tells grep that file1 contains a list of patterns, one per line, to use when searching file2. All matches will be written on the standard output.

---------- Post updated at 15:35 ---------- Previous update was at 15:30 ----------

Looking at your script, just for some closure, you need to move the -n option; that will certainly generate error messages though I don't think it should have affected what was matched from file2.

Code:

grep -n "$line"  file2  >>tmp-file

Hi Agama,
Many thanks for your reply.
Unfortunately, grep -f did not work (no output)
When I substituted the actual first line for the variable (with the -n at the back), it returned the correct row (with row number).
I just can't figure out why it does not work with grep -f or with a loop.
Beginner0302

How is formatted your file? ( strictly ONE pattern per line?)

Hi vbe,
Thanks for your reply.
Yes, it is strictly one pattern per line.
I removed whitespace as mentioned with those two awk commands, but am wondering whether it could still be a whitespace problem?

What editor are you using?

emacs or vi