os

The os module exposes the host environment, process information, signal trapping, file permissions, low-level system info, command-line arguments, and process exit. It is organized into submodules with flat top-level shortcuts for common needs. Import it with import os.

os.env

Function	Signature	Description
`get`	`os.env.get(key: string) → string`	value of an environment variable (empty if unset)
`set`	`os.env.set(key: string, value: string) → bool`	set an environment variable
`unset`	`os.env.unset(key: string) → bool`	remove an environment variable
`has`	`os.env.has(key: string) → bool`	true if the variable is defined
`all`	`os.env.all() → string`	all variables as a JSON object string

os.process

Function	Signature	Description
`pid`	`os.process.pid() → int`	current process ID
`ppid`	`os.process.ppid() → int`	parent process ID
`uid`	`os.process.uid() → int`	user ID
`gid`	`os.process.gid() → int`	group ID
`exit`	`os.process.exit(code?: int) → void`	exit the process with `code` (default 0)
`args`	`os.process.args() → string[]`	command-line arguments
`cwd`	`os.process.cwd() → string`	current working directory
`chdir`	`os.process.chdir(dir: string) → bool`	change the working directory

os.signal

Function	Signature	Description
`notify`	`os.signal.notify() → void`	start trapping SIGINT/SIGTERM/SIGHUP
`trap`	`os.signal.trap() → string`	name of the last received signal (empty if none)
`reset`	`os.signal.reset() → void`	clear the recorded last signal

os.permission

Function	Signature	Description
`readable`	`os.permission.readable(path: string) → bool`	true if the path can be opened for reading
`writable`	`os.permission.writable(path: string) → bool`	true if the path can be opened for writing
`executable`	`os.permission.executable(path: string) → bool`	true if any execute bit is set
`chmod`	`os.permission.chmod(path: string, mode: int) → bool`	change file mode bits

os.syscall

Function	Signature	Description
`arch`	`os.syscall.arch() → string`	CPU architecture (e.g. “arm64”)
`os`	`os.syscall.os() → string`	operating system (e.g. “darwin”)
`hostname`	`os.syscall.hostname() → string`	machine hostname
`pagesize`	`os.syscall.pagesize() → int`	memory page size in bytes
`numCPU`	`os.syscall.numCPU() → int`	number of logical CPUs

os.args

Function	Signature	Description
`all`	`os.args.all() → string[]`	all command-line arguments
`get`	`os.args.get(idx: int) → string`	argument at `idx` (empty if out of range)
`len`	`os.args.len() → int`	number of arguments

os.exit

Function	Signature	Description
`code`	`os.exit.code(code?: int) → void`	exit with `code` (default 0)
`success`	`os.exit.success() → void`	exit with code 0
`failure`	`os.exit.failure() → void`	exit with code 1

Top-level shortcuts

Function	Signature	Description
`getenv`	`os.getenv(key: string) → string`	read an environment variable
`setenv`	`os.setenv(key: string, value: string) → bool`	set an environment variable
`hostname`	`os.hostname() → string`	machine hostname
`arch`	`os.arch() → string`	CPU architecture
`platform`	`os.platform() → string`	operating system
`exitCode`	`os.exitCode(code?: int) → void`	exit with `code` (default 0)
`pid`	`os.pid() → int`	current process ID

Example

import os

print(os.platform())                  // darwin
print(os.getenv("HOME"))

// trap shutdown signals in a long-running program
os.signal.notify()
if os.signal.trap() == "interrupt" {
    os.exit.success()
}

Standard library · View as Markdown · llms-full.txt