How to Properly Redirect Input to `exec.Command` in Go for Commands Like `iptables-restore`?

exec.Command with Input Redirection

To execute a bash command from Go, exec.Command() provides a straightforward solution. However, redirecting input to the command can be a challenge.

Consider the need to update IPTables using the command "/sbin/iptables-restore < /etc/iptables.conf." Attempts to invoke this command using exec.Command() have proven unsuccessful.

To address this, a strategy of providing the filename as input to cmd.StdinPipe() was employed:

stdin, err := cmd.StdinPipe()
if err != nil {
    log.Fatal(err)
}
err = cmd.Start()
if err != nil {
    log.Fatal(err)
}

io.WriteString(stdin, "/etc/iptables.conf")

However, this approach remained ineffective. A viable solution involves reading the content of "/etc/iptables.conf" and writing it to cmd.StdinPipe():

package main

import (
    "io"
    "io/ioutil"
    "log"
    "os/exec"
)

func main() {
    bytes, err := ioutil.ReadFile("/etc/iptables.conf")
    if err != nil {
        log.Fatal(err)
    }
    cmd := exec.Command("/sbin/iptables-restore")
    stdin, err := cmd.StdinPipe()
    if err != nil {
        log.Fatal(err)
    }
    err = cmd.Start()
    if err != nil {
        log.Fatal(err)
    }
    _, err = io.WriteString(stdin, string(bytes))
    if err != nil {
        log.Fatal(err)
    }
}

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