If you are ok, let's simplify a bit with a unique regex:
grep -E '^P [0-9]+ -?24\b' file2.txt
No need the use of cat | grep, it's a useless use of cat.
If you think you can have more space than just one in the regex, you can use one of:
+[[:space:]]+\s+require-PakaPCREswithch ofgrep
The regular expression matches as follows:
| Node | Explanation |
|---|---|
^ |
start of the line anchor |
P |
'P' + space |
[0-9]+ |
any character of: '0' to '9' (1 or more times (matching the most amount possible)) |
|
a space |
-? |
'-' (optional (matching the most amount possible)) |
24 |
'24' |
\b |
word boundary |