fish-shell/doc_src/random.txt

\section random random - generate random number

\subsection random-synopsis Synopsis
\fish{synopsis}
random
random SEED
random START END
random START STEP END
random choice [ITEMS...]
\endfish

\subsection random-description Description

`RANDOM` generates a pseudo-random integer from a uniform distribution. The
range (inclusive) is dependent on the arguments passed.
No arguments indicate a range of [0; 32767].
If one argument is specified, the internal engine will be seeded with the
argument for future invocations of `RANDOM` and no output will be produced.
Two arguments indicate a range of [START; END].
Three arguments indicate a range of [START; END] with a spacing of STEP
between possible outputs.
`RANDOM choice` will select one random item from the succeeding arguments.

Note that seeding the engine will NOT give the same result across different
systems.

You should not consider `RANDOM` cryptographically secure, or even
statistically accurate.

\subsection random-example Example

The following code will count down from a random even number between 10 and 20 to 1:
\fish
for i in (seq (random 10 2 20) -1 1)
    echo $i
end
\endfish
And this will open a random picture from any of the subdirectories:
\fish 
open (random choice **jpg)
\endfish