24.5 Limiting File Sizes

Here is a technique to keep you from creating large files (which can happen by accident, such as runaway programs). To set a maximum file size, use the C shell command (usually in your .cshrc file) limit filesize  max-size . In the Korn shell and bash , use ulimit -f  max-size . You can change the limit from the command line, too. For example, the csh and ksh commands below keep you from creating any files larger than 2 megabytes:

% 

limit filesize 2m


$ 

ulimit -f 2000

With this command, UNIX will refuse to allocate more disk space to any file that grows larger than 2 MB.

Similarly, on Berkeley systems, you can use limit and ulimit to restrict the size of core dump files ( 52.9 ) . Core dumps are generally large files and are often generated for innocuous reasons, such as invoking commands incorrectly. To set a maximum size for core dumps, execute one of these commands:

% 

limit coredumpsize 



max-size


$ 

ulimit -c 



max-size

To eliminate core dumps entirely, use 0 (zero) for max-size . Because core dumps are essential for effective debugging, any users who are actively debugging programs should know the commands unlimit coredumpsize , which removes this restriction in csh -and ulimit -c unlimited for bash and ksh .