Truncate file to a specific size

[former_member544751]

This is what i am trying to do:

exec( 'sh','truncate -s 20000 /path_to_file/filename.txt',8);

How can i truncate a file to a specific size at a specific remote directory that is accessible by Job Server?

Or something that would allow me to cut the file to remove rows of data from the file like "cut -c -20000 filename.txt"?

Regards,
Farha