Shell Programming and Scripting

Hi,

I have a problem that I am trying to solve and would greatly appreciate some input to solve this. I have a file containing variable length of line. Each line in the file has values separated by "," and i need to grep for these values in a some files. For example below is a sample file with 3 lines:

Code:

file1:a,b,c,d
file2:e,f
file3:g,h,i,j,k,l

I have gone pass to read this file line by line but how do i pass each value separated by "," to variable and use it in a grep command.

So basically i need to dynamically generate variables and pass it to grep command for further processing like:

Code:

for a,b,c
grep "$var" file1

for e,f
grep "$var" file2

for g,h,i,j,k,l
grep "$var" file3

Any help on this would be greatly appreciated. Can we use Arrays?

Thanks in advance.

Arrays may be a good idea in this instance. However array implementations vary between the various shells. What shell are you using?

#!/bin/bash

Can pls give an example of doing this? I am trying to use array but have not had success , may be missing something.

Since you have BASH you probably have egrep. It accepts multiple expressions like "a|b|c|d".

You can use IFS to split apart a string on ",", then put it back together with "|"

Since IFS changes how any splitting works in the shell you will want to put it back to what it was after!

Code:

#!/bin/bash

OLDIFS="$IFS"

while IFS=":" read FILE STRING
do
        IFS=","
        ARR=( $STRING )
        IFS="|"
        echo egrep "${ARR[*]}" $FILE
done < filename

IFS="$OLDIFS"

Code:

$ ./script.sh

egrep a|b|c|d file1
egrep e|f file2
egrep g|h|i|j|k|l file3

$

Remove the 'echo' to have it actually run egrep instead of just printing it.

@Corona688 - Nice idea to use egrep, I was going to recommend awk for that bit.

Thanks, this resolves partial problem but now struck with egrep.

Code:

egrep a|b|c|d file1

does not work. Is there any other way i can do this. Only way I can think of is using a loop, to loop over an array, but would appreciate if you have anything else.

In what way does it "not work". Be specific! If it's a bug I can probably fix that with more information. If you don't actually have it, say so.