Math

Sometimes you just need to add a few numbers when you're working on a task. Nu offers a set of basic math operations that you can use:

To get into "math mode", you start the command with an =. This lets Nu know what you're about to write will use operators. Some commands, like where will do this for you so that you don't have to.

Add, Subtract, Multiply, Divide

> = 1 + 3
4

In Nu, you can do the usual add, subtract, multiply and divide with the operators +, -, *, and / respectively. Operator precedence is respected, so 1 + 2 * 3 will be treated as 1 + (2 * 3). Which leads us to parentheses.

Parentheses

You can use parentheses to group math expression in math mode. This allows you to write (1 + 2) * 3 if you want the addition to have higher precedence.

in and not-in

You can check if a value is in a set of values or not using the in and not-in operators.

> = 1 in [1 2 3]
true

> = 1 not-in [1 2 3]
false

=~ and !~

You can check to see if a string is inside of another string, or not inside of another string, using =~ and !~.

> = "foobar" =~ "foo"
true

> = "foobar" !~ "baz"
true

Comparisons

The following comparisons are also available:

• < - less than
• <= - less than or equal to
• > - greater than
• >= - greater than or equal to
• == - equal to
• != - not equal to

Compound operators

Nushell also supports && and || to join two operations that return boolean values, using 'and' and 'or' respectively. For example: ls | where name in ["one" "two" "three"] && size > 10kb

Order of operations

Math operations are evaluated in the follow order (from highest precedence to lowest):

• Parentheses (())
• Multiply (*) and Divide (/)
• Add (+) and Subtract (-)

> = 3 * (1 + 2)
9

Short-hand math mode

A variation of math mode that Nushell supports is called "short-hand" math mode. This is because it gives you a way of accessing columns using a simple short-hand.

You may have already used this functionality before. If, for example, we wanted to only see rows from ls where the entry is at least ten kilobytes, we can write:

> ls | where size > 10kb

The where size > 10kb is a command with two parts: the command names where and the short-hand math expression size > 10kb. We say short-hand because size here is the shortened version of writing $it.size. If we look at the fully expanded form, we would see:

> ls | where { = $it.size > 10kb }

The = gives us the full math mode. Rather than having to type all this out every time a command needs to work with column data, we use this short-hand mode to access column data.

For the expansion to work, the column must appear on the left-hand side of the operation. Above, size appears on the left-hand side of the comparison, which allows the expression to expand into the full math mode block.