Issue deleting all lines (having a specific string) in a file

Shell Programming and Scripting
1

I'm trying to create a script.

There are 2 files - fileA.log & fileB.log
fileA.log has the below data :
aaaa
cccc
eeee

fileB.log has the below data :
cjahdskjah aaaa xyz
jhaskjdhas bbbb abc
ajdhjkh cccc abc
cjahdskjah dddd xyz
jhaskjdhas eeee abc

I need to read each line from fileA.log, check fileB.log for that string and delete the line from fileB.log, if that string exists

Finally the file fileB.log should have the below data :

jhaskjdhas bbbb abc
cjahdskjah dddd xyz

Below is the script that I've used :

File_A=/tmp/fileA.log
File_B=/tmp/fileB.log
while read line
        do
        sed -i "/\b$FileA\b/d" $File_B
done <$File_A

But unfortunately, it is deleting all the lines.

Please let me know what's wrong with my script.

2 
grep -vf fileA.log fileB.log
1 Like
3

Hi,
You must use $line versus $FileA in your line sed:
sed -i "/\b$line\b/d" $File_B

But, your solution read/write file2 as far as number line from file1

Better solution:

$ printf '/\\b%s\\b/d\n' $(<file1.txt) | sed -f - file2.txt
jhaskjdhas bbbb abc
cjahdskjah dddd xyz

or

$ sed -e 's#.*#/\\b&\\b/d#' file1.txt | sed -f - file2.txt
jhaskjdhas bbbb abc
cjahdskjah dddd xyz

Regards.

1 Like
4

Should like cjahdskjah aaaaSTUFF xyz be deleted from fileB.log in your example?

If not modify Yoda's solution as follows:

grep -vwf fileA.log fileB.log
1 Like
5

Thanks Folks!!!

With the input you all gave I got it working with the below script :

while read line
       	do
	grep -v $line fileB.log > $TEMP_FILE
	cat /dev/null > fileB.log
	cat $TEMP_FILE > fileB.log
done <$fileA.log
6

That's massively inefficient. There's no need to invoke grep once per line.

If the lines in fileA.log are not regular expressions, use fixed string matching.

The first cat command it's pointless.

If there are slashes in your data, read will eat them. If there are trailing slashes, lines will be joined.

Regards,
Alister

1 Like
7

Thanks Alister. Have taken your inputs and made the changes as needed.

8

The dread <cr><lf> (Win) vs. <lf> (*nix) vs. <cr> (Mac?) strikes again! :slight_smile: