sys

The sys module provides functions and objects for OS interaction and system-level operations.

Types

Name	Description
`Error`	Error raised for system and I/O failures
`NotFoundError`	Subtype for missing files, paths, or programs
`PermissionDeniedError`	Subtype for permission failures
`AlreadyExistsError`	Subtype for existing-path conflicts
`TimedOutError`	Subtype for timed-out system operations

Functions

`echo ...args`

Prints arguments to the terminal output, separated by spaces, followed by a newline. This always prints to the terminal regardless of I/O redirection.

Parameters:

Name	Type	Description
`...args`		values to print (converted with `ext`)

echo hello world
# prints: hello world

`exit code?`

Exits the script with the given status code.

Parameters:

Name	Type	Description
`code`	`int`	exit status (default: 0)

exit()     # exits with 0
exit 1     # exits with 1

`cd path? func?`

With no arguments, returns the current working directory. With a path, changes the current working directory. If a callable is also provided, the directory is changed only for the duration of that call, then restored.

Parameters:

Name	Type	Description
`path`	`str`	directory path
`func`		callable to run in the new directory

Returns: Current working directory (no arguments), or result of func.

# Print current directory
echo $cd()

# Permanent change
cd /tmp

# Scoped change
cd /tmp do
  echo "In /tmp"
# Back to original directory

Objects

`env`

An object for accessing environment variables.

Indexing

# Get a variable (errors if not set)
let path = env["PATH"]

# Set a variable
env["MY_VAR"] = "hello"

# Unset a variable
env["MY_VAR"] = nil

`env func key: value ...`

Runs a callable with temporary environment variable overrides.

env HOME: /tmp do
  echo $env["HOME"]  # /tmp
# HOME is restored

Methods

`env.get key :default? :else?`

Gets an environment variable with a fallback.

let val = env.get HOME default: /tmp

`args`

An array of command-line arguments passed to the script.

`program`

Identifies what dolang-shell is executing.

For dolang-shell script.dol, this is an fs.Path for script.dol.
For dolang-shell -m foo.bar, this is the string "foo.bar".
In the REPL, this is nil.

`os`

A string indicating the current operating system (e.g., "linux", "macos", "windows").

if (os == "linux")
  echo "Running on Linux"