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## Description A plugin can stop processing while its input reader is still blocked on a connected, idle producer. Have the SDK release a call's original list or byte input automatically when its complete response finishes writing, or when the engine drops its output stream. Returning lazy output does not itself release input. Other calls and engine-call result streams are unaffected; no new public plugin API is needed. Defer both completion and output-drop cleanup while the SDK is forwarding stream input to an engine call. An early response from `call_decl` or `eval_closure_with_stream` must not truncate that input, including redirected output that closes before its input consumer finishes. The core reader owns a concrete hold, attached before publishing the engine-call header and released when the forwarding writer ends or its consumer sends `Drop`. Since `PipelineData` is opaque, forwarding an unrelated stream conservatively holds the original input too. Engine-call result readers remain outside this cleanup. Skip completion cleanup while the plugin has disabled GC through `set_gc_disabled(true)`, preserving background input reads after a response. This follows the last successfully written and flushed plugin-wide GC option, not Nushell's GC configuration. The setting is shared by all calls, so overlapping calls must coordinate updates: the last write wins for both GC and input retention. Completion reads the setting without waiting for transport I/O; concurrent GC updates retain their wire order. An early output `Drop` still requests input cleanup, regardless of GC, but honors active SDK forwarding holds. Remove the output/input association before sending `End`, so a normal EOF acknowledgement does not cancel those background reads. Keep the association in the output writer's signal, cancelling input before waking a dropped writer so concurrent `End` cannot lose the cleanup. Cancelled reads report `ShellError::Interrupted` once instead of successful EOF, so a consumer can distinguish interrupted input from a complete stream. The reader discards its local queue and sends `Drop` once. Its registration remains until the producer sends `End`, allowing in-flight messages to arrive safely. No wire protocol changes or new dependencies are needed. The interruption retains the input stream's span. A transport error dequeued by the current read takes precedence over cancellation; errors behind that message are discarded with the queue. Association setup and local cleanup are infallible. A poisoned writer mutex does not skip unlinking, releasing a hold, or the single terminal `End` attempt; normal flow-control errors and actual write/flush errors remain visible. Completion cleanup cannot introduce a second response after a successful one. Regression tests cover idle reads, cancellation races, late messages, GC opt-out, call isolation, engine-call forwarding, and interruption versus normal EOF, including both stream types through `serve_plugin_io`. ## User-facing changes (Release notes) Fixed Rust plugin input readers remaining blocked after a response finishes or its output is dropped. Background reads of original input without an explicit call to `set_gc_disabled(true)` are now interrupted when the complete response finishes, even if plugin GC is disabled in Nushell's configuration. Cancelled input reads report `ShellError::Interrupted`, not successful EOF. Calling `set_gc_disabled(true)` preserves background input reads after completion. This setting is plugin-wide and last write wins, so overlapping calls must coordinate their GC updates. Both completion and early output-drop cleanup preserve input forwarded by the SDK until forwarding finishes or its consumer drops it. An early output drop still requests cleanup when GC is disabled. Engine-call result readers are unaffected. ## Additional notes Related to #12129; this does not implement general pipeline interruption. Validated on Linux: 272 tests and 38 doctests across the five plugin crates, plus 121 root plugin integration tests (one Windows-only test ignored). The 40 SDK lifecycle tests also passed five repeated runs. Formatting, `cargo nuclippy`, `cargo nuclippy-tests`, and `typos` passed. Full workspace runtime tests and Windows/macOS CI have not been run. Cleanup wakes SDK-owned input reads; it does not interrupt arbitrary iterators, blocked transport writes, or independent work such as HTTP requests, or retract data already received. Output completion can still wait for that independent work. A producer that never sends `End` can leave a stream registration until the transport closes. Developed with AI assistance.
Nushell
A new type of shell.
Table of Contents
- Status
- Learning About Nu
- Installation
- Configuration
- Philosophy
- Goals
- Officially Supported By
- Contributing
- License
Status
This project has reached a minimum-viable-product level of quality. Many people use it as their daily driver, but it may be unstable for some commands. Nu's design is subject to change as it matures.
Learning About Nu
The Nushell book is the primary source of Nushell documentation. You can find a full list of Nu commands in the book, and we have many examples of using Nu in our cookbook.
We're also active on Discord; come and chat with us!
Installation
To quickly install Nu:
# Linux and macOS
brew install nushell
# Windows
winget install nushell
To use Nu in GitHub Action, check setup-nu for more detail.
Detailed installation instructions can be found in the installation chapter of the book. Nu is available via many package managers:
For details about which platforms the Nushell team actively supports, see our platform support policy.
Configuration
The default configurations can be found at sample_config which are the configuration files one gets when they start up Nushell for the first time.
It sets all of the default configuration to run Nushell. From here one can then customize this file for their specific needs.
To see where config.nu is located on your system simply type this command.
$nu.config-path
Please see our book for all of the Nushell documentation.
Philosophy
Nu draws inspiration from projects like PowerShell, functional programming languages, and modern CLI tools. Rather than thinking of files and data as raw streams of text, Nu looks at each input as something with structure. For example, when you list the contents of a directory what you get back is a table of rows, where each row represents an item in that directory. These values can be piped through a series of steps, in a series of commands called a 'pipeline'.
Pipelines
In Unix, it's common to pipe between commands to split up a sophisticated command over multiple steps. Nu takes this a step further and builds heavily on the idea of pipelines. As in the Unix philosophy, Nu allows commands to output to stdout and read from stdin. Additionally, commands can output structured data (you can think of this as a third kind of stream). Commands that work in the pipeline fit into one of three categories:
- Commands that produce a stream (e.g.,
ls) - Commands that filter a stream (e.g.,
where type == "dir") - Commands that consume the output of the pipeline (e.g.,
table)
Commands are separated by the pipe symbol (|) to denote a pipeline flowing left to right.
ls | where type == "dir" | table
# => ╭────┬──────────┬──────┬─────────┬───────────────╮
# => │ # │ name │ type │ size │ modified │
# => ├────┼──────────┼──────┼─────────┼───────────────┤
# => │ 0 │ .cargo │ dir │ 0 B │ 9 minutes ago │
# => │ 1 │ assets │ dir │ 0 B │ 2 weeks ago │
# => │ 2 │ crates │ dir │ 4.0 KiB │ 2 weeks ago │
# => │ 3 │ docker │ dir │ 0 B │ 2 weeks ago │
# => │ 4 │ docs │ dir │ 0 B │ 2 weeks ago │
# => │ 5 │ images │ dir │ 0 B │ 2 weeks ago │
# => │ 6 │ pkg_mgrs │ dir │ 0 B │ 2 weeks ago │
# => │ 7 │ samples │ dir │ 0 B │ 2 weeks ago │
# => │ 8 │ src │ dir │ 4.0 KiB │ 2 weeks ago │
# => │ 9 │ target │ dir │ 0 B │ a day ago │
# => │ 10 │ tests │ dir │ 4.0 KiB │ 2 weeks ago │
# => │ 11 │ wix │ dir │ 0 B │ 2 weeks ago │
# => ╰────┴──────────┴──────┴─────────┴───────────────╯
Because most of the time you'll want to see the output of a pipeline, table is assumed.
We could have also written the above:
ls | where type == "dir"
Being able to use the same commands and compose them differently is an important philosophy in Nu.
For example, we could use the built-in ps command to get a list of the running processes, using the same where as above.
ps | where cpu > 0
# => ╭───┬───────┬──────┬───────────┬──────┬─────────┬───────┬────────────┬──────────╮
# => │ # │ pid │ ppid │ name │ user │ status │ cpu │ cpu_time │ mem │
# => ├───┼───────┼──────┼───────────┼──────┼─────────┼───────┼────────────┼──────────┤
# => │ 0 │ 2240 │ 9872 │ Slack.exe │ dev │ Running │ 16.40 │ 1min 12sec │ 178.3 MB │
# => │ 1 │ 16948 │ 9872 │ Slack.exe │ dev │ Running │ 16.32 │ 48sec │ 205.0 MB │
# => │ 2 │ 17700 │ 4632 │ nu.exe │ dev │ Running │ 3.77 │ 2sec │ 26.1 MB │
# => ╰───┴───────┴──────┴───────────┴──────┴─────────┴───────┴────────────┴──────────╯
Opening files
Nu can load file and URL contents as raw text or structured data (if it recognizes the format). For example, you can load a .toml file as structured data and explore it:
open Cargo.toml
# => ╭──────────────────┬────────────────────╮
# => │ bin │ [table 1 row] │
# => │ dependencies │ {record 25 fields} │
# => │ dev-dependencies │ {record 8 fields} │
# => │ features │ {record 10 fields} │
# => │ package │ {record 13 fields} │
# => │ patch │ {record 1 field} │
# => │ profile │ {record 3 fields} │
# => │ target │ {record 3 fields} │
# => │ workspace │ {record 1 field} │
# => ╰──────────────────┴────────────────────╯
We can pipe this into a command that gets the contents of one of the columns:
open Cargo.toml | get package
# => ╭───────────────┬────────────────────────────────────╮
# => │ authors │ [list 1 item] │
# => │ default-run │ nu │
# => │ description │ A new type of shell │
# => │ documentation │ https://www.nushell.sh/book/ │
# => │ edition │ 2018 │
# => │ exclude │ [list 1 item] │
# => │ homepage │ https://www.nushell.sh │
# => │ license │ MIT │
# => │ metadata │ {record 1 field} │
# => │ name │ nu │
# => │ repository │ https://github.com/nushell/nushell │
# => │ rust-version │ 1.60 │
# => │ version │ 0.72.0 │
# => ╰───────────────┴────────────────────────────────────╯
And if needed we can drill down further:
open Cargo.toml | get package.version
# => 0.72.0
Plugins
Nu supports plugins that offer additional functionality to the shell and follow the same structured data model that built-in commands use. There are a few examples in the crates/nu_plugins_* directories.
Plugins are binaries that are available in your path and follow a nu_plugin_* naming convention.
These binaries interact with nu via a simple JSON-RPC protocol where the command identifies itself and passes along its configuration, making it available for use.
If the plugin is a filter, data streams to it one element at a time, and it can stream data back in return via stdin/stdout.
If the plugin is a sink, it is given the full vector of final data and is given free reign over stdin/stdout to use as it pleases.
The awesome-nu repo lists a variety of nu-plugins while the showcase repo shows off informative blog posts that have been written about Nushell along with videos that highlight technical topics that have been presented.
Goals
Nu adheres closely to a set of goals that make up its design philosophy. As features are added, they are checked against these goals.
-
First and foremost, Nu is cross-platform. Commands and techniques should work across platforms and Nu has first-class support for Windows, macOS, and Linux.
-
Nu ensures compatibility with existing platform-specific executables.
-
Nu's workflow and tools should have the usability expected of modern software in 2022 (and beyond).
-
Nu views data as either structured or unstructured. It is a structured shell like PowerShell.
-
Finally, Nu views data functionally. Rather than using mutation, pipelines act as a means to load, change, and save data without mutable state.
Officially Supported By
Please submit an issue or PR to be added to this list.
- zoxide
- starship
- oh-my-posh
- Couchbase Shell
- virtualenv
- atuin
- clap
- Dorothy
- Direnv
- x-cmd
- vfox
- Windmill
- Lacy
Contributing
See Contributing for details. Thanks to all the people who already contributed!
License
The project is made available under the MIT license. See the LICENSE file for more information.