执行psql命令时os/exec上的输出不完整

package main

import (
    "fmt"
    "os/exec"
)

func main() {
    cmd := exec.Command("psql", "--version")
    output, err := cmd.Output()
    if err != nil {
        fmt.Println("执行psql命令时出错:", err)
        return
    }
    fmt.Println(string(output))
}

package main

import (
    "bufio"
    "fmt"
    "os/exec"
)

func main() {
    cmd := exec.Command("psql", "--version")
    stdout, err := cmd.StdoutPipe()
    if err != nil {
        fmt.Println("创建输出管道失败:", err)
        return
    }

    err = cmd.Start()
    if err != nil {
        fmt.Println("执行psql命令时出错:", err)
        return
    }

    reader := bufio.NewReader(stdout)
    output := ""
    for {
        line, err := reader.ReadString('\n')
        if err != nil {
            fmt.Println("读取输出时出错:", err)
            break
        }
        output += line
    }

    err = cmd.Wait()
    if err != nil {
        fmt.Println("等待命令执行完毕时出错:", err)
        return
    }

    fmt.Println(output)
}