grep - multiple positions

I was wondering if anybody can help me with this. I have the following code to look for a space in position #48 and I want to change it so it looks in position 48, 59, and 50 for spaces. How can I do that?

Here's the current code -
grep -v '^.\{48\}[[:space:]].*' <infile> > <outfile>

Any help would be appreciated.

You can never mind this question, I figured it out.

Maybe you could post your solution to the problem so that others with similar issues can benefit from your experience

Cheers
ZB

Sorry about that, good idea. Here's my solution -
grep -v '^.\{48\}[[:space:]].*[[:space:]].*[[:space:]].*' <infile> > <outfile>