Nushell
Updated: 06 December 2023
About
Nushell makes use of command outputs as data that can be transformed, it makes use of pipes that connnect commands together in a functional-programming usage style
Thinking in Nu
Nushell works with results using pipes, this is similar to >
in bash but isn’t exactly the same
Immutability
Variables are immutable, however values can be shadowed, so I can create a shadowing x
based on a previous x
like so:
Scoping
Nushell uses scoped environmments in blocks, so a command can use a value within its scope like so:
Fundamentals
Types of Data
The describe
command returns the type of a variable
Conversions
The into
command can convert variable types
Strings
Strings can be created as:
- Double quotes:
"hello world"
- Single quotes:
'hello: "world"'
- Interpolated:
$"my number = (40 + 2)"
- Bare:
hello
Bools
Booleans are simply true
and false
Dates
Dates can be in the following formats:
2022-02-02
2022-02-02T14:30:00
2022-02-02T14:30:00+05:00
Durations
Nushell has the following durations:
ns
nanosecondus
microsecondms
millisecondsec
secondmin
minutehr
hourday
daywk
week
And can be used like so:
Or in calculations
Ranges
Ranges can be done as 1..3
for example, by default the end is inclusive, ranges can also be open ended ..2
or 2..
Records
Records hold key-value pairs, and may or may not have commas between entry names:
A record is the same as a single row of a table
Records can be iterated over by transposing them into a table:
And accessing properties can be done like:
Or
Lists
Lists are ordered sequences of data and use []
with optional ,
separators. The below will create alist of strings
A list is the same as a single column table
Indexing lists can be done with a .
as with records:
Or using ranges:
Tables
Tables can be created with the following syntax:
Tables can also be created from json
Internally tables are just a list of records
Blocks
Blocks of code are denoted using {}
, for example:
Loading Data
Open Files
Files can be opened with the open
command:
Nu will parse the file if it can and will return data and not just a plain string
If a file extension isn’t what the type usually has, we can still parse the file, we just ned to tell nu that it’s a specific format, so we can do this like so:
Manipulating Strings
String data can be manipulated using things like the lines
command which will split each line into a row:
And we can further apply the split
command on the column to split it by some specific character:
Additionally, we can use trim
:
And lastly, we can transform it into a table with formal column names with some additional properties on the split
command:
Fetch Urls
We can also fetch remote files which will then also be converted into data like so:
Cheatsheet
Moving around the File System
Nushell provides commands for normal file-system related tasks which are similar to common commands such as:
Listing Files
Or listing a specific file type
Or even globs
Globs
You can also use the glob
method directly to find files recursively:
The
glob
method returns a list of strings versus thels
method which returns a list of file objects
Deleting Branches
We can use a script like the following to delete all git branches other than the current branch
Stopping All Docker Containers
The Docker CLI outputs data that’s nicely structured for working with the NuShell table structure.
We can kill all containers by parsing the data into a table and stopping them individually