[SOLVED] grep for full raw multi-line string

Issue

This the following

$ echo '
  - key: val
    baz: foo
' | grep -F "$(
cat <<EOM
  - key: val
    foo: baz
EOM
)"

The output is a partial match

  - key: val

but I would like to get nothing if the whole given heredoc string is fully found and nothing otherwise.

Is it possible to grep for full raw multi-line string (not a regular expression)? If so, then how should it be done?

Solution

First thing is that to get exact match in grep you will need to use -x option.

However, as I suspected initially grep -x will fail for even the full match due to presence of line breaks.

One trick is to use tr to strip all line breaks from original and pattern strings and use -x like this:

echo '
  - key: val
    baz: foo
' | tr -d '\n' | grep -q -xF -- "$(
cat <<EOM | tr -d '\n'
  - key: val
    foo: baz
EOM
)" && echo "match" || echo "nope"


echo '
  - key: val
    baz: foo
' | tr -d '\n' | grep -q -xF -- "$(
cat <<EOM | tr -d '\n'
  - key: val
    baz: foo
EOM
)" && echo "match" || echo "nope"

Output:

nope
match

Note use of -q to suppress normal output of grep and use only the exit code. Also used -- to separate options from pattern.

Answered By - anubhava

Answer Checked By - David Marino (WPSolving Volunteer)