os

The os module provides process and environment information. Use it for configuration supplied by the operating system rather than hard-coding secrets or deployment settings.

import "os"

var port = os.getenv("PORT")
if port == "" {
    port = "8080"
}
print(port)
print(os.getwd())
print(os.hostname())

# argv() is the program command line (index 0 is the invocation name)
for arg in os.argv() {
    print(arg)
}

Avoid using exit() inside reusable library code. Environment and temporary-file operations can raise IOError. argv() does not accept arguments and returns a fresh list each call; mutating that list does not change the program arguments.

Command-line arguments

argv() presents the command line from the Goblin program's point of view. Index 0 is its invocation name; remaining elements are the arguments passed after it. With goblin run, the source path is the invocation name — for example goblin run app.goblin foo bar makes argv() return ["app.goblin", "foo", "bar"]. Arguments that look like flags (such as -v or --help) are forwarded only when they appear after the source file. Put the source file first. Leading flags are rejected. For CLI help use goblin run -h or goblin help run (alone, with no source file). Compiled executables from build-exe see the real process argv (the binary path at index 0). In the REPL, argv() is [""] so interactive sessions do not expose the goblin process arguments. Use argv() when a program needs flags or positional inputs from the shell; prefer getenv() for configuration that should not be visible on the command line.

var args = os.argv()
if args.size < 2 {
    print("usage:", args[0], "<file>")
    os.exit(1)
}
print("input:", args[1])

Configuration from the environment

getenv() returns nil for a missing key; pass default= to supply a fallback value (for example os.getenv("PORT", default="8080")), or use environ() when a program needs to inspect the complete environment dictionary.

var env = os.environ()
var mode = env.get("APP_MODE", default="development")
var debug = mode == "development"
print(debug)

setenv() changes only the environment of the current Goblin process and processes it starts. It does not persist after the program exits.

Temporary paths and process identity

tempdir() and tempfile() accept optional directory and pattern arguments in that positional order, and return created paths. They are helpful for generated output and tests. These functions do not accept named arguments.

var directory = os.tempdir("", "goblin-")
var filename = os.tempfile(directory, "data-")
print(directory)
print(filename)

getpid(), getppid(), getuid(), geteuid(), getgid(), getegid(), and getgroups() expose identity information supplied by the host operating system; getpagesize() reports the memory page size. Availability and exact values can vary by platform.