Just had to match a string pattern that is like this: -30 29 334 -5 9 33 -31 -289 667 (for example, there is a trailing space)
The regex:
^(?:[\-0-9]+\ ){9}$
In words, the regex matches start of line (^), followed by at least one character that is – or 0-9, followed by a space. The match is in a non-capture group (?: … ) and the pattern in the non-capture group is to be repeated 9 times, followed by the end of the line ($)