exec grep and zcat problems

[adam777]

Hello

I am working with php on redhat and have an odd problem.

I have created a temp file in a directory that stores paths and filenames of .Z files I wish to process.

So I zcat them one at a time into a second temp file using eg

exec("zcat FILENAME.Z > zcatTemp");

then grep the contents of zcatTemp eg

exec("grep 'mySearchString' zcatTemp > resultsFile);

However the two commands above do not work. I can output the uncompressed contents of the files via System but that is of no use to me, I need the results in a file for processing

any ideas? I've played with permissions by setting the files to 777 but that doesnt appear to have any effect.

Thanks for your time

Adam