Grep pattern that has double quotes and variable substitution surrounded by single quotes

Question

So, Let's say I have the following pattern:

Thisisatest="1"

in a file called file.

And I want to match the exact string above but for whatever reason, I choose to loop over some numbers from a list, use those as variable and try to do this:

Thisisatest="$varhere"

Where the above $varhere is equal to the number above, being 1. (while i mentioned looping over number, this was just a future possible use cases for this and remain an example)

Now to make things easier, say I want to match the above exact pattern while using the above variable and it's content:

grep 'Thisisatest="$varhere"' file

Where file contain the string Thisisatest="1" and $varhere contain the number 1.

Problem being, this wouldn't work because variable expansion doesn't occur when in-between single quotes (like above).

Here the failed attempt at countering this:

1. substitution of content from variable substitution

echo "${varhere/[0-9]*/Thisisatest=\"$varhere\"}"

Here I use echo to see if it output the right string so it can be used as input for grep...it output this instead:

'Thisisatest="'1'"

2. Add more quotes

echo "'Thisisatest="${varhere}"'"

output:

'Thisisatest='1''

echo ''''Thisisatest=\"${varhere}\"''''

output:

Thisisatest="'1'"

The rest is obvious... Now the very last attempt above seems to be close to what i want, but still not it.

Any way(s) to do the above?

Answer 1

grep "Thisisatest=\"${varhere}\""

works for me. "\" flips the "I am a special character" flag of the following character through ONE shell interpretation.