grep bug

[Dag-ErlingSmørgrav]

Barney Wolff <barney at databus.com> writes:
> On Sun, Feb 08, 2004 at 06:36:23PM -0800, Kris Kennaway wrote:
>> kkenn at rot13:~ grep -r foo / > /dev/null
>> grep: /dev/network: Permission denied
>> grep: /dev/geom.ctl: Permission denied
>> grep: /dev/devctl: Permission denied
>> grep: /dev/ata: Permission denied
>> grep: /dev/console: Permission denied
>> grep in realloc(): error: allocation failed
>> ^C^C^CAbort (core dumped)
>
> grepping /dev/zero seems to fail.

/dev/zero will provide grep with infinite amounts of data.  So will
/dev/random.  Yet other device nodes (serial ports for instance) will
cause grep to block because they provide neither data nor EOF.

The /dev/zero case is a little special because grep tries to read in
an entire line, but /dev/zero provides an endless string of zeroes
with no EOL in sight.  /dev/random, on the other hand, is pretty much
guaranteed to provide EOL every 256 bytes on average.

DES
-- 
Dag-Erling Smørgrav - des at des.no