use -F in grep
$ cat test.txt
"Limit reached."[\
]"
test
"Limit reached."[\
]"
$ grep -F '"Limit reached."[\
]"' test.txt
"Limit reached."[\
]"
"Limit reached."[\
]"
As per Manual page,
>
> -F, --fixed-strings, --fixed-regexp
> Interpret PATTERN as a list of fixed strings, separated by newlines, any of which is to be matched. (-F is specified by> POSIX,
> --fixed-regexp is an obsoleted alias, please do not use it new scripts.)
>