Why Does Piping Commands in Go's `exec.Command()` Fail, and How Can I Fix It?

Executing Piped Commands in Go Using exec.Command()

Q: Piping Commands Fails with Exit Status 1

When attempting to pipe commands using exec.Command(), the following error occurs:

ps, "cax | grep myapp"

Why does this command fail while ps cax works?

A: Idiomatic Piping with exec.Command()

Passing the entire command to bash can resolve the issue, but there is a more idiomatic solution:

1. Create separate commands for each step (ps and grep).
2. Connect their standard input and output using pipes.
3. Execute ps first, then grep.

Code Example:

package main

import (
    "fmt"
    "os/exec"
)

func main() {
    grep := exec.Command("grep", "redis")
    ps := exec.Command("ps", "cax")

    // Connect ps's stdout to grep's stdin.
    pipe, _ := ps.StdoutPipe()
    defer pipe.Close()
    grep.Stdin = pipe

    // Run ps first.
    ps.Start()

    // Run and get the output of grep.
    res, _ := grep.Output()

    fmt.Println(string(res))
}

Explanation:

• grep and ps are created as separate commands.
• A pipe is created from ps's stdout to grep's stdin.
• ps is started first, ensuring that its output is available for grep.
• grep is then executed and its output is retrieved, providing the desired result.

The above is the detailed content of Why Does Piping Commands in Go's `exec.Command()` Fail, and How Can I Fix It?. For more information, please follow other related articles on the PHP Chinese website!