sys (slug)

slug.sys

slug.sys — operating system interface

Process management, environment variables, and shell command execution.

Process handles

spawnProc, waitProc, and killProc work with numeric process handles. Spawn a process with spawnProc, wait for it to finish with waitProc, and terminate it early with killProc.

For simple synchronous command execution, prefer exec.

TOC

• env(str)
• exec(cmd, timeout)
• exit(exitCode)
• killProc(handle)
• setEnv(key, value)
• spawnProc(cmd)
• waitProc(handle, timeout)

Functions

env(str)

fn slug.sys#env(@str str) -> @str

reads an environment variable by name.

Returns nil if the variable is not set.

@effects(‘io’)

Effects: io

exec(cmd, timeout)

fn slug.sys#exec(@str cmd, @num timeout = 0) -> [@str, @str]

runs a shell command synchronously and returns [stdout, stderr].

Blocks until the command completes or timeout elapses. A timeout of 0 means wait indefinitely. Both stdout and stderr are returned as strings regardless of exit code.

@effects(‘io’)

Effects: io

exit(exitCode)

fn slug.sys#exit(@num exitCode) -> nil

terminates the current process with the given exit code.

Deferred functions are not run. Exit code 0 indicates success; non-zero indicates failure.

killProc(handle)

fn slug.sys#killProc(@num handle) -> @bool

sends a termination signal to a spawned process.

Returns true if the signal was delivered successfully.

@effects(‘io’)

Effects: io

setEnv(key, value)

fn slug.sys#setEnv(@str key, @str value) -> @str

sets an environment variable.

The format is "NAME", "value". Returns the value that was set.

@effects(‘io’)

Effects: io

spawnProc(cmd)

fn slug.sys#spawnProc(@list cmd) -> @num

spawns a process from a command list and returns a process handle.

The command list format is ["executable", "arg1", "arg2", ...]. Use waitProc to block until the process finishes, or killProc to terminate it.

@effects(‘io’)

Effects: io

waitProc(handle, timeout)

fn slug.sys#waitProc(@num handle, @num timeout = 0) -> @num

waits for a spawned process to finish and returns its exit code.

Returns -1 if timeout elapses before the process exits. A timeout of 0 means wait indefinitely.

@effects(‘io’)

Effects: io