bash text search: find if the content of one file

Question

Closed. This question needs to be more focused. It is not currently accepting answers.

---

Want to improve this question? Update the question so it focuses on one problem only by editing this post.

Closed 6 years ago.

Say we have two files: a.txt and b.txt. Each file has multiple lines of text.

How do I write a shell script to check if all of the content of a.txt exists in b.txt?

---

Thx for the hints guys, i didn't noticed -q will output 0 if successfully matched.

I end up with:

if grep a.txt -q -f b.txt ; then

else

fi

Answer 1

try grep

cat b.txt|grep -f a.txt

Answer 2

Here is a script that will do what what you are describing:

run: sh SCRIPT.sh a.txt b.txt

# USAGE:   sh SCRIPT.sh TEST_FILE CHECK_FILE
TEST_FILE=$1
CHECK_FILE=$2

## for each line in TEST_FILE
while read line ; do

    ## check if line exist in CHECK_FILE; then assign result to variable
    X=$(grep "^${line}$" ${CHECK_FILE})


    ## if variable is blank (meaning TEST_FILE line not found in CHECK_FILE)
    ## print 'false' and exit
    if [[ -z $X ]] ; then
        echo "false"
        exit
    fi

done < ${TEST_FILE}

## if script does not exit after going through each line in TEST_FILE,
## then script will print true
echo "true"

Assumptions:

• line order from a.txt does not matter

Answer 3

Using grep

grep -f a.txt b.txt

Answer 4

You need to write a loop that iterates over each line in a.txt and use grep (or some other means) to see if that line is in b.txt. If you find any instance where it is not in b.txt, then you can provide the answer: not all lines match. If you find no such instances, you can conclude that all lines match.

Capturing the output of grep using backticks would likely be useful:

if [`grep -v $line b.txt`==  ""]; then

kind of thing.

If you have specific questions about how to iterate over the contents of a file, you should ask a specific question about that, showing what you tried.