从java运行Grep命令

我想从java运行grep命令

这是我试过的。请让我知道，为什么它不显示输出

public static void main(String args[]) throws IOException{
    Runtime rt = Runtime.getRuntime();
    String[] cmd = { "/bin/sh", "-c", "grep 'Report Process started' server.log|wc -l" };
    Process proc = rt.exec(cmd);
    BufferedReader is = new BufferedReader(new InputStreamReader(proc.getInputStream()));
    String line;
    while ((line = is.readLine()) != null) {
        System.out.println(line);
    }
    System.out.println("Done");
}

---

您不需要将grep的输出传输到

wc-l

。只需像这样使用

grep-c

：

String[] cmd = {"/bin/sh", "-c", "grep -c 'Report Process started' /path/to/server.log"};

String logdata = new Scanner(new File("/path/to/server.log")).useDelimiter("\\Z").next();
final String needle = "Report Process started";
int occurrences = 0;
int index = 0;
while (index < logdata.length() && (index = logdata.indexOf(needle, index)) >= 0) {
    occurrences++;
    index += needle.length();
}

尽管我必须说，在Java中正确地执行此操作要干净得多。考虑这样的代码：

String[] cmd = {"/bin/sh", "-c", "grep -c 'Report Process started' /path/to/server.log"};

String logdata = new Scanner(new File("/path/to/server.log")).useDelimiter("\\Z").next();
final String needle = "Report Process started";
int occurrences = 0;
int index = 0;
while (index < logdata.length() && (index = logdata.indexOf(needle, index)) >= 0) {
    occurrences++;
    index += needle.length();
}

String logdata=new Scanner（新文件（“/path/to/server.log”））。使用分隔符（\\Z”）.next（）；
最终字符串needle=“报告过程已开始”；
int=0；
int指数=0；
而（索引=0）{
事件++；
索引+=针的长度（）；
}

您必须检查是否有任何错误

private static void printStream(InputStream in) throws IOException {
    BufferedReader is = new BufferedReader(new InputStreamReader(in));
        String line;
        while ((line = is.readLine()) != null) {
            System.out.println(line);
        }
}
public static void main(String args[]) {
    try {
        Runtime rt = Runtime.getRuntime();
        String[] cmd = {"/bin/sh", "-c", "grep 'Report Process started' server.log|wc -l"};
        Process proc = rt.exec(cmd);
        printStream(proc.getInputStream());
        System.out.println("Error : ");
        printStream(proc.getErrorStream());
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

---

你为什么要外包

grep

？@chrylis，我想在日志文件中获得“Report Process started”字符串的计数。。。有没有其他方法可以让我计算这个字符串的数量…suggestRight，那么为什么不自己用Java来计算呢？或者运行shell脚本中的所有内容？请尝试提供日志文件的完整路径。