问题背景

有时候会操作linux指令读取或修改文件，封装一个常用的Linux工具类比较方便

LinuxUtils工具类

1 LinuxUtils工具类

package com.yg.util;

import lombok.extern.slf4j.Slf4j;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.LineNumberReader;

/**
 * @author suolong
 * @time 2022-03-19 10:57
 **/
@Slf4j
public class LinuxUtils {


    public static boolean downloadHdfsFile(String hdfsPath, String outputPath) {
        String cmd = "hdfs dfs -cat " + hdfsPath + "/* > " + outputPath;
        log.info("downloadHdfsFile cmd:" + cmd);
        return executeCmd(cmd);
    }

    public static void addHead(String filePath, String labelField) {
        //在test.txt文件中的第一行加入id appname msg-cn
        // 1i表示在第一行追加  \t表示以制位符
        //sed -i "1iid\tappnmae\tmsg-cn" test.txt 
        String headcmd = "sed -i \"1iid\\t";
        if (org.apache.commons.lang3.StringUtils.isNotEmpty(labelField)) {
            String[] labelArray = labelField.split(",");
            for (int i = 0; i < labelArray.length; i++) {
                if (i < labelArray.length - 1) {
                    headcmd = headcmd + labelArray[i] + "\\t";
                } else {
                    headcmd = headcmd + labelArray[i] + "\" ";
                }
            }
            headcmd = headcmd + filePath;
        } else {
            headcmd = "sed -i \"1iid" + "\" " + filePath;
        }
        log.info("add head===headcmd:" + headcmd + "====" + LinuxCmdUtils.getGrepCmdReturn(headcmd));
        return;
    }

    public static boolean executeCmd(String commandStr) {
        log.info("run command = " + commandStr);
        String[] cmd = {"/bin/sh", "-c", commandStr};

        boolean isSuc = false;
        try {
            Process proc = Runtime.getRuntime().exec(cmd);
            if (proc.waitFor() == 0) {
                isSuc = true;
            }
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
        return isSuc;
    }


    public static boolean executeLinuxCmd(String cmd) {

        boolean result = false;

        System.out.println("got cmd : " + cmd);
        Runtime run = Runtime.getRuntime();
        //InputStream in=null;
        try {
            Process process = run.exec(cmd);
            //执行结果 0 表示正常退出
            int exeResult = process.waitFor();
            if (exeResult == 0) {
                System.out.println("执行成功");
                result = true;
            }
        } catch (Exception e) {
            log.error("LinuxCmdUtils.executeLinuxCmd error", e);
        }
        return result;
    }

    /**
     * 获取linux命令执行的结果,cat 之类
     *
     * @param cmd
     * @return
     */
    public static String getCmdResult(String cmd) {

        String result = "";
        try {

            Process process = Runtime.getRuntime().exec(cmd);
            InputStreamReader ir = new InputStreamReader(process.getInputStream());
            LineNumberReader input = new LineNumberReader(ir);
            String line;
            while ((line = input.readLine()) != null) {
                result = line;
            }

        } catch (IOException e) {
            System.err.println("IOException " + e.getMessage());
        }
        return result;
    }

    /**
     * grep 类的shell命令
     *
     * @param cmdStr
     * @return
     */
    public static String getGrepCmdReturn(String cmdStr) {

        String[] cmd = new String[3];

        cmd[0] = "/bin/sh";
        cmd[1] = "-c";
        cmd[2] = cmdStr;

        //得到Java进程的相关Runtime运行对象
        Runtime runtime = Runtime.getRuntime();
        StringBuffer stringBuffer = null;
        try {

            Process process = runtime.exec(cmd);

            BufferedReader bufferReader = new BufferedReader(
                    new InputStreamReader(process.getInputStream()));

            stringBuffer = new StringBuffer();

            String temp = null;

            while ((temp = bufferReader.readLine()) != null) {
                stringBuffer.append(temp);
            }


        } catch (IOException e) {
            e.printStackTrace();
        }

        return stringBuffer.toString();
    }

    public static int getFileRows(String path) {
        FileReader in;
        int rows = 0;
        try {
            in = new FileReader(path);
            LineNumberReader reader = new LineNumberReader(in);
            reader.skip(Long.MAX_VALUE);
            rows = reader.getLineNumber();
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return rows;
    }

    public static void main(String[] args) {

        System.out.println(LinuxCmdUtils.getGrepCmdReturn("dmidecode -s system-serial-number|grep -v \"#\""));
    }
}

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