I was testing some code that I wrote for analyzing cryptograms, and decided that the easiest way to do so would be to get some random text, drawn from the letters A-Z. A moments thought yielded this method, without even programming anything:
tr -d -c A-Z < /dev/urandom | dd ibs=10000 count=1
The tr generates the required data, and the dd truncates it to the desired number of characters. But for tidiness, I'd like to have the output broken up so that each line consists of 50 characters, with spaces inserted between every 5 characters (I won't begrudge you if you leave a dangling space at the end of each line). I couldn't figure out a simple way to get that to happen all in one command line and using standard utilities. I can of course write a little Python utility, or even perl, but can anyone think of a clever short way to do this?
Addendum: Tom pointed out something interesting about the command that I listed above: it doesn’t work the way I think it does. Apparently the ibs is the input block size, which dd dutifully allocates, and the count is the number of read system calls that the system issues. For reasons which escape me, it does not try to make sure that it actually received a full input block: it will nicely return short blocks if it finds them, and doesn’t bother retrying to get more. Hence, it works rather erratically when using a pipe as input, particularly when the writes from the upstream process may flush in odd intervals.