[英]How to Execute Core Show channels Command in java and also grep Channels in it
[英]how to execute command "ps -eaf | grep myprocess" in java
如果有任何代码可以找到任何其他进程的 PID,我用谷歌搜索并检查了 SO。 有一种解决方案可以在其中使用命令“ps -eaf | grep myprocess”创建 shell 脚本并从 java 执行该脚本。
但我想使用 java ProcessBuilder 或 Runtime 方法执行。 下面是我尝试过的代码,它没有给我 null 作为 output。
import java.io.*;
public class TestShellCommand {
public static void main(String args[]) {
Process p = null;
String command = "ps -ef | grep myProcess";
try {
// p = new ProcessBuilder(command).start();
p = Runtime.getRuntime().exec(command);
BufferedReader br[] = new BufferedReader[2];
br[1] = new BufferedReader(new InputStreamReader(p.getErrorStream()));
br[0] = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
if(br[0].readLine() == null){
System.out.println("The input stream is null.");
}
while ((line = br[0].readLine()) != null) {
System.out.println(line);
}
try {
br[0].close();
} catch (Exception a) {
a.printStackTrace();
}
try {
br[1].close();
} catch (Exception a) {
a.printStackTrace();
}
} catch (Exception grrr) {
grrr.printStackTrace();
} finally {
try {
closeStreams(p);
p.destroy();
} catch (Exception r) {
r.printStackTrace();
}
}
}
static void closeStreams(Process p) throws IOException {
p.getInputStream().close();
p.getOutputStream().close();
p.getErrorStream().close();
}
}
该命令的 output 是:
java TestShellCommand
The input stream is null.
{sdc@ip-172-31-32-49}[26] echo $?
0
请让我知道我的代码中是否有任何错误,因为当我从 shell 手动搜索时,我确实得到了预期的 output,如下所示:
ps -ef | grep myProcess
root 7433 1 0 10:33 ? 00:00:00 myProcess hello
sdc 19894 14130 0 11:24 pts/7 00:00:00 grep myProcess
[更新代码 - 没有 grep 命令]
import java.io.*;
public class TestShellCommand {
public static void main(String args[]) {
Process p = null;
String [] command = {"ps", "-eaf"};
try {
p = Runtime.getRuntime().exec(command);
BufferedReader br[] = new BufferedReader[2];
br[1] = new BufferedReader(new InputStreamReader(p.getErrorStream()));
br[0] = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
if(br[0].readLine() == null){
System.out.println("The input stream is null.");
}
while ((line = br[0].readLine()) != null) {
System.out.println(line);
}
// Then code to find by process name by using string methods ...
try {
br[0].close();
} catch (Exception a) {
a.printStackTrace();
}
try {
br[1].close();
} catch (Exception a) {
a.printStackTrace();
}
} catch (Exception grrr) {
grrr.printStackTrace();
} finally {
try {
closeStreams(p);
p.destroy();
} catch (Exception r) {
r.printStackTrace();
}
}
}
static void closeStreams(Process p) throws IOException {
p.getInputStream().close();
p.getOutputStream().close();
p.getErrorStream().close();
}
}
当我将命令传递为:
new String[]{"/bin/sh","-c", "ps -eaf | grep "+ "myProcess" +" | grep -v grep"}
- 空响应。new String[] {"ps", "-eaf", "grep -m 1 myProcess", "awk -F ' ' '{print $2}' "}
- 空响应。提前感谢任何线索。
正如@Slimo 的答案所示,您必须启动 shell 来执行 shell 命令(管道),并阅读错误 stream 以确定可能出了什么问题。
启动子进程而不使用waitFor()
或同时使用 stdout 和 stderr 可能会导致问题,使用文件重定向或在本例中合并 stderr -> stdout 并仅读取一个 stream :
String procname = "myProcess";
String[] cmd = new String[]{"bash","-c", "ps -eaf | grep "+procname+" | grep -v grep"}
ProcessBuilder pb = new ProcessBuilder(cmd);
pb.redirectErrorStream(true);
Process process = pb.start();
process.getInputStream().transferTo(System.out);
int rc = process.waitFor();
if (rc != 0)
throw new RuntimeException("Failed rc="+rc+" cmd="+Arrays.toString(cmd));
在以后的 JDK 中,您不需要 ProcessBuilder,您可能会在ProcessHandle
返回的数据结构中找到所有进程属性:
ProcessHandle.allProcesses()
.filter(ph -> ph.info().command().isPresent() && ph.info().command().get().contains(procname))
.forEach(ph -> System.out.println("PID: "+ph.pid()+" command: "+ph.info().command()))
您的问题是您尝试在命令中使用 pipe,因此您需要 shell 来执行它。 您可以使用以下命令:
p = new ProcessBuilder("/bin/sh", "-c", "ps -aux | grep myProcess").start();
您可以在此处阅读更多信息: 使用 Java ProcessBuilder 执行管道命令
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