In order to calculate an average for a list of numbers, file sizes, durations, or range of numbers, or a table with columns containing numeric values you can use the math avg command. This command is part of the math module of Nushell. When the input is a list then the result is a single value with the average of all values in the list. If you use a table as input the result is a record where the key is the column name and the value the average of all values in that column. Finally it is possible to have a single value as input and the result is the same value obviously.

The math module in Nushell has a lot of useful commands to work with numeric values. You can use the math sum command to calculate the sum of a multiple numeric values. The input of the command can be a list of numbers, durations, file sizes, or a range or table with columns containing numeric values. The result is a single numeric value with the sum of all values in the input. The math sum command can also be used on a table with multiple numeric columns. It will return a record with the sum of all values for each column.

In Nushell we can use a lot a math related commands to get for example the minimum and maximum values of a list of numbers. In the math module you can find the commands math min and math max. You can use these commands to get the minimum and maximum values of a list of numbers, durations, file sizes, a range and tables.

To check if a string value starts or ends with a given string you can use the str starts-with and str ends-with commands. The command returns a boolean value: true if the string starts or ends with the given string and false otherwise. The commands are case sensitive by default. You can use the --ignore-case (or the shorthand -i) to ignore casing while checking if a the string starts or ends with a given string.
To input can be a string value and then that string value is checked. If the input is an array of string values, then each element is checked. It is also possible to check values in a record or table. You need to pass the names of the field(s) or column(s) that you want to check the string values of.

A lot of commands have output displayed as table. It is possible to use different themes for tables. If you run the command table --list you get all available themes. At the moment the following themes are available: basic, compact, compact_double, default, heavy, light, none, reinforced, rounded, thin, with_love, psql, markdown, dots, restructured, ascii_rounded, basic_compact, single, double. You can use a theme with the table command by using the --theme option and the name of the theme. For example to have a different table theme for the ls command you can use ls | table --theme light.
If you want to change the theme for all table output you can set the configuration option $env.config.table.mode. To make this configuration setting permanent you can add it to config.nu file.

When you start Nushell you can see a nice ASCII art elephant. That is Ellie a cute and friendly elephant mascot for Nushell. Elephants are popular as you can see them in other products like Mastodon and Gradle. It is possible to summon Ellie in your Nushell environment by running the ellie command. This command is part of the std library and you need to run use std ellie or std use * first.

To get the names of columns in a table or the keys of a record you can use the columns command. The command returns a list of string values that are the column or key names. When the input is table the column names are returned, and when the input is a record the names of the keys are returned.

The build-in HTTP client in Nushell can be used to interact with REST APIs and websites. If the URL you want to invoke has query parameters than you can use the url build-query command. The url build-query command transforms a record or table to URL encoded key/value pairs joined with an ampersand (&). Each key and value is separated by an equal sign (=). The command can expand a key with a list value to separate key/value pairs with the same key if the key is defined in a record.

The string module contains a lot of useful commands to work with strings. If you want to join several values from a list into a single string you can use the str join command. The command accepts as argument the character(s) to use for joining the values. If you don’t specify the character(s) as argument the default value '' (empty string) is used.

Sometimes you want to transform a string value into a URL encoded value, so it can be used as part of a valid URL. For example a string with spaces or special characters can not be used in a URL as is, but needs to be URL encoded. Nushell has the url encode command to achieve this. You can simple run this command on a string value and the result is a URL encoded value. With the option --all or -a even more special characters like a dot (.) are encoded. The input of the command can be a string value or a list of string values. But it is also possible to use a record or table structure, but then you need to add as extra argument the name or names of the keys or columns of which the string values should be encoded.
Oppossed to URL encoding a value you can also decode a URL encoded value using the url decode command. This command doesn’t have a special option to run. Just like with the url encode command the url decode command works on strings, list of strings, records and tables. If the input is a record or table the name of key or column of which the values must be decoded must be passed as extra arguments.

The Nushell command enumerate adds an index value to each item in a list. The index value is stored in an extra column named index. You can use this column to filter data based on the index value.

Nushell has very useful commands to filter lists and tables. When you have a list with null values, you can use the compact command to filter out the null values. With the option --empty you can also filter out empty items like empty strings, empty lists and empty records. If you want to filter out rows in a table where a column contains a null value, you can use the compact command followed by the name of the column.