如何在java Runtime.exec中使用管道

Question

我得到null作爲此命令行的輸出。

Process result = Runtime.getRuntime().exec(new String[]{"/usr/bin/find",baseDir+"/..","-type","f","|","/usr/bin/grep",filter1,"|","/usr/bin/grep",filter2,"|","/usr/bin/wc","-l"}); 
result.waitFor(); 
BufferedReader echo = new BufferedReader(new InputStreamReader(result.getInputStream())); 
writer.print(echo.readLine()); 
echo.close(); 

它是管道「|」嗎？

Answer 1

也許。要得到像|這樣的shell命令，請使用/bin/bash作爲exec的第一個參數，第二個參數爲-c，第三個參數爲整個字符串（包括find，參數和管道等）。

Process result = Runtime.getRuntime().exec(new String[]{"/bin/bash", "-c", "/usr/bin/find " + baseDir+"/.. -type f | /usr/bin/grep " +filter1 + | /usr/bin/grep "+filter2+" | /usr/bin/wc -l"});