io

The io module provides interactive user input functions for CLI scripts.

Functions¶

Function	Returns	Description
`io.confirm(msg, default=False)`	`bool`	Prompt the user for a yes/no confirmation
`io.prompt(msg, default="", secret=False)`	`string`	Prompt the user for text input. Set `secret=True` to hide input (e.g. passwords)

Examples¶

Confirmation prompt¶

if io.confirm("Deploy to production?"):
    exec("kubectl apply -f prod.yaml")
else:
    print("Aborted.")

Confirmation with default¶

# Default to True — pressing Enter confirms
if io.confirm("Continue?", default=True):
    print("Continuing...")

Text prompt¶

name = io.prompt("Enter cluster name")
print("Deploying to:", name)

Prompt with default value¶

region = io.prompt("AWS region", default="us-east-1")
print("Using region:", region)

Secret input¶

token = io.prompt("API token", secret=True)
os.setenv("API_TOKEN", token)

io.reader¶

An io.reader represents a readable stream of data, exposing the following methods:

Method	Returns	Description
`read(count)`	`bytes`	Reads up to `count` bytes from the stream, returning them as a `bytes` object (empty on EOF)
`bytes()`	`bytes`	Buffers all remaining content of the stream into host memory, returns it as a single `bytes` object, and automatically closes the stream
`lines()`	`iterator`	Returns a Starlark iterator yielding lines of text sequentially (trailing newlines are kept)
`close()`	`None`	Closes the underlying stream, releasing the OS resource

Example: Consuming a Stream Line-by-Line¶

# Assuming reader is obtained from a file path or HTTP response
reader = fs.path("app.log").get_reader()

for line in reader.lines():
    if "ERROR" in line:
        print("Found error:", line.strip())

reader.close() # Explicitly release the resource

io.writer¶

An io.writer represents a writable stream of data, exposing the following methods:

Method	Returns	Description
`write(data)`	`int`	Writes data to the stream. Accepts a `string`, `bytes`, or another `io.reader` (which automatically pipes the reader's content into the writer and closes the reader on completion)
`close()`	`None`	Flushes any remaining buffered bytes and closes the stream

Example: Streaming a File¶

# Stream content from one file to another using zero-copy piping
reader = fs.path("source.dat").get_reader()
writer = fs.path("destination.dat").get_writer()

# Writes all content and automatically closes the reader
writer.write(reader)

writer.close() # Close the writer to flush and sync to disk

Note: All io functions that can fail support try_ variants that return a Result instead of raising an error.