The max file size in unix is determined by the ulimit option. The ulimit stands for user limit which specifies the largest file that can be created by the user.

$ulimit

2097152

means that the max size of a file that can be created is 2097152 bytes or 2048 KB.

We can also reset the ulimit value

$ulimit=1 specifies that the user limit is now 512 bytes(1 refers to 512 block) and is only active for this session.

A normal user can decrease the ulimit value but only the superuser(root) has the permissions to increase this value.

Hope this clears your doubt. Thank you.

Suresh.