Executing Shell Commands

Agenda

• How to execute shell commands (like ls, mkdir or grep) in Golang.
• How to pass I/O to a running command through stdin and stdout, as well as manage long running commands.

The Exec Package

• We can use the official os/exec package to run external commands.
• When we execute shell commands, we are running code outside of our Go application. In order to do this, we need to run these commands in a child process.
• Each command is run as a child process within the running Go application, and exposes Stdin and Stdout attributes that we can use to read and write data from the process.

Examples

1. Running Basic Shell Commands
2. Executing Long Running Commands
3. Custom Output Writer
4. Passing Input To Commands With STDIN
5. Killing a Child Process

Conclusion

• So far, we learned multiple ways to execute and interact with unix shell commands. Here are some things to keep in mind when using the os/exec package:

• Use cmd.Output when you want to execute simple commands that don’t usually give too much output For functions with continuous or long-running output, you should use cmd.Run and interact with the command using cmd.Stdout and cmd.Stdin

• In production applications, its useful to keep a timeout and kill a process if it isn’t responding for a given time. We can send termination commands using context cancellation.

References: