dapper sudo

[Alexander Skwar]

Jack Bowling wrote:
> On Tue, Jul 04, 2006 at 02:44:14PM +0100, Toby Kelsey wrote:
>> boricua wrote:
>> >how come dapper does not allow me to do this
>> >
>> > sudo cat /dev/null >  /var/log/apache2/error.log
>> >
>> 
>> Because the sudo only applies to the command 'cat', not the redirection.
>> 
>> Try
>>   sudo dd of=/var/log/apache2/error.log < /dev/null
>> or
>>   sudo tee /var/log/apache2/error.log < /dev/null
>> 
>> 
>> It is a bug that there is no obvious command to truncate a file.
> 
> 
> Could somebody tell me if there is any difference between the above cat
> command and 
> 
> [sudo] echo "" > /var/log/apache2/error.log
> 
> assuming one has sudo'ed to a root shell?

That assumption is the difference. So, yes, there IS a *HUGE* difference
between

	sudo -s
	echo > /var/log/apache2/error.log

(BTW: No need for the "echo" here, unless you're really after an empty
line).

and

	sudo tee /var/log/apache2/error.log < /dev/null


The difference is, that the shell "executing" "> /var/log/apache2/error.log"
is run with root rights. That's actually more-or-less the same as doing

	sudo sh -c " > /var/log/apache2/error.log"

Alexander Skwar
-- 
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robbers there will be.
		-- Lao Tsu