Add Replace The Current Process With An External Command as a go til.

go/replace-the-current-process-with-an-external-command.md

@@ -0,0 +1,31 @@
+# Replace The Current Process With An External Command
+
+Go's `syscall.Exec` function can be used to execute an external program.
+Instead of forking a child process though, it runs the external command in
+place of the current process. You need to give the function three pieces of
+information: the location of the binary, the pieces of the command to be
+executed, and relevant environment. Here is a simple example.
+
+```go
+package main
+
+import 'fmt'
+import 'os'
+import 'syscall'
+
+func main() {
+    // get the system's environment variables
+    environment := os.Environ()
+
+    // get a slice of the pieces of the command
+    command := []string{"tmux", "new-session", "-s", "burrito"}
+
+    err := syscall.Exec("/usr/local/bin/tmux", command, environment)
+    if err != nil {
+        fmt.Printf("%v", err)
+    }
+}
+```
+
+When this program is executed, it will replace itself with a new tmux
+session named *burrito*.