浅谈各种编程语言怎么调用外部命令

import os


retcode = os.system('ls /root')  # retcode = 0

import os


out1 = os.popen('ls /root').read() # out1即为ls /root命令执行结果


p = os.popen('cat /home/.env')
out2 = p.readlines() # out2是按行分的列表
p.close()  # 关闭管道, 没有返回值

import subprocess


retcode = subprocess.call(['ls', '-l'])
retcode = subprocess.call('ls -l', shell=True)

import subprocess


result = subprocess.check_output(['ls', '-l'])
result = subprocess.check_output('ls -l', shell=True)

import subprocess


ret1 = subprocess.Popen(['ls', '-l'])
ret2 = subprocess.Popen('ls -l', shell=True)


ret3 = subprocess.Popen('ls -l', shell=True, cwd='/home')  # cwd参数表示进入指定目录执行


# 新开一个python3进程并执行两条命令
obj = subprocess.Popen(['python3'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
# out_error_list = obj.communicate('print("hello")')
obj.stdin.write('print(1)\n')
obj.stdin.write('print(2)')
out_error_list = obj.communicate() # 获取标准输出和标准错误元组
obj.stdin.close()


# 获取标准输出和标准错误
cmd_out = obj.stdout.read()  # '1\n\2\n'
obj.stdout.close()
cmd_error = obj.stderr.read()  # ''
obj.stderr.close()

import java.io.InputStreamReader;
import java.io.BufferedReader;


public class test {
    public static void main(String[] args) {
        try {
            String[] cmd = new String[]{"/bin/sh", "-c", "ls"};
            Process ps = Runtime.getRuntime().exec(cmd);
            BufferedReader br = new BufferedReader(new InputStreamReader(ps.getInputStream()));
            StringBuffer sb = new StringBuffer();
            String line;


            while ((line = br.readLine()) != null) {
                sb.append(line).append("\n");
            }


            String result = sb.toString();
            System.out.println(result);
            ps.waitFor();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

const { exec } = require('child_process');


exec('ls -l', ['/var/www'], (err, stdout, stderr) => {
    if(err) {
        console.log(err);
        return;
    }
    console.log(`stdout: ${stdout}`);
    console.log(`stderr: ${stderr}`);
});

const { exec } = require('child_process');
const path = require('path');


exec('ls -al', { cwd: path.join(process.cwd(), 'scripts') }, (err, stdout, stderr) => {
    if(err) {
        console.log(err);
        return;
    }
    console.log(`stdout: ${stdout}`);
});

const { execFile, execFileSync } = require('child_process');
const StringDecoder = require('string_decoder').StringDecoder;
const decoder = new StringDecoder('utf8');


execFile('curl', ['-I', 'cip.cc'], (err, stdout, stderr) => {
    if(err) {
        console.log(err);
        return;
    }
    console.log(`stdout: ${stdout}`);
});




const stdout = execFileSync('node', ['-v']);
const str = decoder.write(stdout);
console.log(str);

const {spawn}  = require('child_process');
const fs = require('fs');
const spawnObj = spawn('curl', ['cip.cc'], {encoding: 'utf-8'});


spawnObj.stdout.on('data', function(chunk) {
    console.log(chunk.toString());
});


spawnObj.stderr.on('data', (data) => {
    console.log(data);
});


spawnObj.on('close', function(code) {
    console.log(`close code : ${code}`);
})


spawnObj.on('exit', (code) => {
    console.log(`exit code : ${code}`);
    let fd = fs.openSync('test.txt', 'r');
    fs.close(fd, function(err) {
        if(err) {
            console.error(err);
        }
    });
});

package main


import (
    "bytes"
    "fmt"
    "log"
    "os/exec"
)


const ShellToUse = "bash"


func Shellout(command string) (error, string, string) {
    var stdout bytes.Buffer
    var stderr bytes.Buffer
    cmd := exec.Command(ShellToUse, "-c", command)
    // exec.Command(command).Output() 非shell运行, 直接获取字节输出
    cmd.Stdout = &stdout
    cmd.Stderr = &stderr
    err := cmd.Run()
    return err, stdout.String(), stderr.String()
}


func main() {
    err, out, errout := Shellout("ls -ltr")
    if err != nil {
        log.Printf("error: %v\n", err)
    }
    fmt.Println("--- stdout ---")
    fmt.Println(out)
    fmt.Println("--- stderr ---")
    fmt.Println(errout)
}