fish-shell/doc_src/cmds/random.rst

.. _cmd-random:

random - generate random number
===============================

Synopsis
--------

| ``random``
| ``random`` *SEED*
| ``random`` *START* *END*
| ``random`` *START* *STEP* *END*
| ``random`` choice [*ITEMS* ...]

Description
-----------

``random`` generates a pseudo-random integer from a uniform distribution. The
range (inclusive) depends on the arguments.
No arguments indicate a range of 0 to 32767 (inclusive).

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 from START to END (both START and END included).

Three arguments indicate a range from START to 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.

Example
-------

The following code will count down from a random even number between 10 and 20 to 1:

::
 
    for i in (seq (random 10 2 20) -1 1)
        echo $i
    end


And this will open a random picture from any of the subdirectories:

::

    open (random choice **.jpg)


Or, to only get even numbers from 2 to 20::

    random 2 2 20

Or odd numbers from 1 to 3::
  
    random 1 2 3 # or 1 2 4