Is there a way to to get the input/minput command to find an exact match?

I want it to find only the string:

login:

That's a single space followed by login: and no trailing spaces. Using
the UNIX grep command I would find it using:

grep '^ login:$' file_name

Instead, input/minput is catching any line with login: within it, such
as:

Last login: Tue Aug 17 16:03:20 from 10.195.10.8


Thanks
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