Why Doesn\'t Setting an Environment Variable in Go Persist in My Terminal Session?

Environment Variable Not Persisting in Terminal Session

Problem

In a Go program, setting an environment variable using the "os" package affects the program's environment, but the variable is not set in the current terminal session.

package main

import (
    "os"
    "fmt"
)

func main() {
    _ = os.Setenv("FOO", "BAR")
    fmt.Println(os.Getenv("FOO"))
}

Running the program prints "BAR" as expected, indicating that the environment variable was set for the program. However, when checking the environment variable in the terminal using the echo command, it remains empty.

Solution

When a new process is created, it inherits a copy of the parent process's environment. Any changes made to the environment in the new process do not propagate back to the parent process.

To make the environment variable persist in the current terminal session, the program needs to spawn a new shell after modifying the environment. This can be achieved using the exec package:

package main

import (
    "os/exec"
)

func main() {
    _ = os.Setenv("FOO", "BAR")

    // Spawn a new shell with the updated environment
    cmd := exec.Command("bash")
    cmd.Stdin = os.Stdin
    cmd.Stdout = os.Stdout
    cmd.Stderr = os.Stderr

    // Start the shell
    err := cmd.Start()
    if err != nil {
        fmt.Println(err)
        return
    }

    // Wait for the shell to terminate
    err = cmd.Wait()
    if err != nil {
        fmt.Println(err)
        return
    }
}

Now, running this program will set the environment variable "FOO" to "BAR" in the current terminal session.

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