`sys` module

Process-level information and control: identity (platform, version, arch, pid, hostname, user), command-line arguments, environment variables, working directory, and process termination.

import "sys" as sys;

print("bnl",   sys.version, "on", sys.platform, sys.arch);
print("pid:",  sys.pid());
print("user:", sys.username());
print("argv:", sys.argv());
print("cwd:",  sys.cwd());

Constants

Name	Description
`sys.platform`	`"windows"`, `"linux"`, `"darwin"`, …
`sys.version`	bnl interpreter version string.
`sys.arch`	CPU architecture: `"x86_64"`, `"arm64"`, `"x86"`, `"arm"`, or `"unknown"`.

Command-line arguments

Function	Description
`sys.argc()` → number	Count of args passed after the script path.
`sys.arg(i)` → string \| null	The i-th argument (0-indexed), or null if out of range.
`sys.argv()` → list	All CLI args as a list of strings.

Environment variables

Function	Description
`sys.env(name)` → string \| null	Look up one environment variable.
`sys.setenv(name, value)` → null	Set or overwrite an env var. Throws if name is empty or contains `=`.
`sys.unsetenv(name)` → null	Remove an env var. No-op if it doesn't exist.
`sys.envs()` → map	Snapshot of every environment variable as a `{KEY: value}` map.

Process control

Function	Description
`sys.exit(code)`	Terminate with the given exit code. Runs atexit handlers.
`sys.abort()`	Abnormal termination — no atexit handlers; dumps core on Unix. Use for "unrecoverable" cases where `exit` would be misleading.

Process & host info

Function	Description
`sys.pid()` → number	Current process id.
`sys.cpu_count()` → number	Number of logical CPUs, or 0 if unknown.
`sys.hostname()` → string	Machine hostname.
`sys.username()` → string \| null	Current user name, or null if unknown.
`sys.home()` → string \| null	User home directory (`$HOME` on Unix, `%USERPROFILE%` on Windows), or null if unset.
`sys.executable()` → string	Full path to the running bnl interpreter binary.
`sys.script()` → string \| null	Path of the entry `.bnl` script, or null for REPL / `-e` inline code.

Paths

Function	Description
`sys.cwd()` → string	Current working directory. UTF-8 on every OS.
`sys.chdir(path)` → null	Change the working directory. Throws if the path is invalid.
`sys.tempdir()` → string	OS temp directory (`%TEMP%` / `/tmp` / `$TMPDIR`).