random 6-digit number

1 
 $ python -c 'import random; print(random.randint(0,1000000-1))'

Sept. 19, 2018, 10:42 p.m. — johntellsall

Explanation

StackOverflow has a dozen different ways to generate numbers, all of which fall apart after 3-4 digits. This solution requires Python to be installed, but is simple and direct.

Limitations

Requires Python, it's not a pure-Bash solution

Alternative one-liners

0

(Pseudo)random 6-digit number 

 $ let N=0 N=N+10**{0..5}*${RANDOM:0:1}

Dec. 7, 2019, 3:26 p.m. — CK

Explanation

Rather than calling out to python to create a pseudorandom number, we can use the builtin functions of bash to do this more quickly and with less code.

$RANDOM is the builtin random number function in bash. It yields an integer up to 5 digits in length, so this method elects to sample just the first digit from each of the six calls made to $RANDOM. let lends its arithmetic capabilities to construct the 6-digit result piecewise, so that:

๐‘ต = ๐’™โ‚ + 10๐’™โ‚‚ + 100๐’™โ‚ƒ + 1000๐’™โ‚„ + 10000๐’™โ‚… + 100000๐’™โ‚†

where ๐’™แตข are the 6 initial digits taken from the 6 calls to $RANDOM.

Limitations

This method doesn't preclude the possibility of leading zeroes counting towards the 6-digit total.