cat /dev/urandom

Lane lane at
Wed Jul 27 01:12:08 GMT 2005

On Tuesday 26 July 2005 20:03, you wrote:
> I don't use backticks, so this'll have the equivalent "$()".
> The command: cat /dev/urandom
> is passed to the shell and the shell executes "cat" and sends
> the output to the screen without possibility of executing anything
> (except the magic stuff recognized by your terminal emulator -- I hope
> it can't execute stuff).
> The command: $(cat /dev/random)
> is passed to the shell, where it does "command substitution" on
> it first and then executes it, where "it" is the output of the
> cat command, which could be destructive.
> Simpler tests are:
> pwd
> echo pwd
> $(echo pwd)
> echo $(echo pwd)
I think the backticks (and shell variables) actually send the output to a 
pipe, not the screen.

I use them in recursive shell scripts, on occasion, which are run by the cron 

Either technique can be a blessing ... or a curse, depending on how you use 


More information about the freebsd-questions mailing list