os / terminal (Environment)

These two modules answer questions about the machine the program is running on. They read only; nothing here changes the system.

import { osName, osArch, osHostname, osUser, osCpuCount } from os;
import { isTTY } from terminal;

os

Function	Returns	Example
osName()	string	linux, windows
osArch()	string	x86_64
osHostname()	string	The machine’s network name
osUser()	string?	The current user, or null if unavailable
osCpuCount()	int	Number of logical processors

import { osName, osArch, osCpuCount } from os;

int main() {
    print(osName());        // linux
    print("\n");
    print(osArch());        // x86_64
    print("\n");
    print(osCpuCount());    // 8
    print("\n");
    return 0;
}

osUser() returns string? because the current user is not always determinable; check for null before using it.

These are diagnostic values. Use them to report an environment or to size a piece of work, not to decide whether a feature exists: asking whether a file is present tells you more than inferring it from the platform name.

terminal

bool isTTY()

Whether standard output is connected to a real terminal. false when output is redirected to a file or piped into another program.

import { isTTY } from terminal;

int main() {
    if (isTTY()) {
        print("=== Report ===\n");   // a person is reading
    } else {
        print("report\n");           // something is parsing
    }
    return 0;
}

This is the check that decides whether to decorate output. The compiler makes the same decision for its own: saqut ir prints color on a terminal and plain text when redirected, so piped output stays clean.

To emit an ANSI color code you have to build the escape byte yourself, since string literals support only \n, \t, \r, \b, \\, and \". There is no \x1b or \u001b:

import { decode } from utf8;

string escape() {
    byte[] esc = [27 as byte];      // ESC, decimal 27
    return decode(esc);
}

Reproducibility

Every function on this page reports something about the environment, so the same program prints different values on a different machine, or when its output is redirected. Keep them out of code whose result has to be identical everywhere.