Linux – how to pipe the output of cut to the foreach command

cutgreplinuxpipescripting

I have the cut command I want that grabs the first word in each line of a file.
I then want to put each word from the cut command into a foreach.
I then want to do a grep command inside the body of the foreach to grep for that word in another file.

Something like this:

@array = (cut /tmp/10218.after -f1); 
foreach $word (@lines) { 
   grep $word /tmp/10218.before;
}

Obviously the @array assignment doesn't work. How do I get around this?

I'm sure there are many ways I just don't know what they are or which is best or good enough.

Best Answer

In bash

while read -r word
do
    grep -q "$word" file.before
    if [ $? -ne "0" ]
    then
        echo "$word not in file"
     fi
done < <(cut -f1 -d" " file.after)

The -q to grep tells it to be quiet, you can then interrogate $? to see if there was a match 0 or not 1.

Related Question