procgroup

Documentation

Overview

Package procgroup is the one way abcd bounds a command together with every process it starts: the command leads its own process group, and the bound kills that group through the pid the command's own handle holds, never by a pattern and never another process.

Index

• func Bound(cmd *exec.Cmd, grace time.Duration)
• func Kill(cmd *exec.Cmd) error
• func Lead(cmd *exec.Cmd)

Functions

func Bound

func Bound(cmd *exec.Cmd, grace time.Duration)

Bound makes cmd, built with exec.CommandContext, lead its own process group, and makes the context's end kill the whole group: a pipeline, a recipe's shell or a background child the command started ends with it rather than outliving the bound. The kill is addressed to the group through the pid cmd's handle holds while the command is not yet reaped, so the group id is still its own. grace bounds the wait for the command's output after it exits or is killed (exec.Cmd.WaitDelay), so a process that left the group and held the output pipe cannot make the bound unbounded.

A group of its own is out of the terminal's foreground group, so an interrupt typed at the terminal does not reach it: a caller that should stop on one ends the context on it (signal.NotifyContext).

func Kill

func Kill(cmd *exec.Cmd) error

Kill sends SIGKILL to the process group cmd leads (Lead), addressed through the pid cmd's handle holds. Call it only after cmd started and before Wait has reaped it, so the group id is still its own. A command that never started has no group: Kill returns os.ErrProcessDone for it, as a Cancel does for a process that is gone.

func Lead

func Lead(cmd *exec.Cmd)

Lead makes cmd lead its own process group once started, for a caller that bounds it itself (its own timer and select) and stops it with Kill.