From d07f5e449aa6715b83b66c7b755c596018eb88d3 Mon Sep 17 00:00:00 2001
From: "chen.yang" <chen.yang@yuzhen-iot.com>
Date: Wed, 11 Aug 2021 14:31:39 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=20=E5=B8=A6=20Cancel=20?=
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Signed-off-by: chen.yang <chen.yang@yuzhen-iot.com>
---
 .../Go/Package/OS/Exec/Golang_执行外部程序.md | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/Software/Development/Language/Go/Package/OS/Exec/Golang_执行外部程序.md b/Software/Development/Language/Go/Package/OS/Exec/Golang_执行外部程序.md
index e19fb8b..f1e8450 100644
--- a/Software/Development/Language/Go/Package/OS/Exec/Golang_执行外部程序.md
+++ b/Software/Development/Language/Go/Package/OS/Exec/Golang_执行外部程序.md
@@ -2,6 +2,8 @@
 
 需要使用 os/exec 包。
 
+## 1.基本用法
+
 示例如下：
 
 ```go
@@ -28,3 +30,31 @@ exec.Cmd 有 Start、Wait、Run、Output 等方法，其中
 * Wait：阻塞进程，等待命令执行结束, 经常与 Star 配合使用；
 * Run：阻塞进程，直到命令执行结束，相当于 Start+Wait 的组合；
 * Output：阻塞进程，直到命令执行结束，比 Run 方法多返回程序的 stdout。
+
+## 2.带 Cancel 的外部命令调用
+
+```go
+func MakeCmdWithCancel(name string, arg ...string) (*exec.Cmd, context.CancelFunc) {
+    ctx, cancel := context.WithCancel(context.Background())
+    cmd := exec.CommandContext(ctx, name, arg...)
+    cmd.Env = append(cmd.Env, "USER=root")
+    cmd.Env = append(cmd.Env, "HOME=/home/root")
+    cmd.Env = append(cmd.Env, "SHELL=/bin/sh")
+    cmd.Env = append(cmd.Env, "SHLVL=1")
+    cmd.Env = append(cmd.Env, "LOGNAME=root")
+    cmd.Env = append(cmd.Env, "XDG_RUNTIME_DIR=/run/user/0")
+    cmd.Env = append(cmd.Env, "PATH=/usr/local/bin:/usr/bin:/bin:/xt/scripts:/usr/local/sbin:/usr/sbin:/sbin:/xt/scripts")
+    return cmd, cancel
+}
+
+func main() {
+    // Sleep 20s
+    sleep, cancel := MakeCmdWithCancel("sleep", "20")
+    sleep.Start()
+    // 3s 后 Cancel 掉
+    time.Sleep(3 * time.Second)
+    cancel()
+    // 会立刻退出
+    sleep.Wait()
+}
+```