How to use Process Builder in java to run Linux shell command?

Question

I am trying to execute two linux commands using JAVA program:

1. ifconfig| grep -A 1 'eth0'|tail -1|cut -d ':' -f 2|cut -d ' ' -f 1

This command gives me and "IP address" and I have to read and use it in the second command

2. ./executeTest.sh "IP address"

My function which I am using to run these commands is this:

public int exec(String[] command, Map<String, String> envt, StringBuilder stdout, StringBuilder stderr, int timeoutSeconds) throws TimeoutException, Exception{
        int exitValue = -1;
        final File stdoutFile = File.createTempFile("test_", "extproc.out");
        final File stderrFile = File.createTempFile("test_", "extproc.err");
        Process process = null;
        try{    
            ProcessBuilder pb = new ProcessBuilder(command);
            if(envt!=null){
                for(Entry<String, String> entry : envt.entrySet()){
                    pb.environment().put(entry.getKey(), entry.getValue());
                }
            }
            pb.redirectOutput(stdoutFile);
            pb.redirectError(stderrFile);

            process = pb.start();

            boolean timedOut = false;

            timedOut = !(process.waitFor(timeoutSeconds, TimeUnit.SECONDS));

            if(timedOut){
                System.out.println("Timed out waiting for process to complete.");
                try{    
                    process.destroyForcibly();
                }catch(Exception killEx){
                    System.out.println("Error while terminating runaway process"+ killEx);
                }   
            }else{
                exitValue = process.exitValue();    
            }

            stdout.append(FileUtils.readFileToString(stdoutFile));
            stderr.append(FileUtils.readFileToString(stderrFile));

            if(timedOut){
                throw new TimeoutException();
            }
        }finally{
            if(stdoutFile.exists()){
                //File.deleteDirectory(stdoutFile);
            }
            if(stderrFile.exists()){
                //FileUtils.deleteDirectory(stdoutFile);
            }
            if(process != null){
                process.destroy();
            }

        }
        return exitValue;
    }

However, I am getting the following error when I call this function for both the commands written above:

java.io.IOException: Cannot run program "ifconfig | grep -A 1 'eth0' | tail -1 |cut -d ':' -f 2 |cut -d ' ' -f 1": error=2, No such file or directory
        at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
        at IOxUnifiedSanityTestSuite.starWebServer.exec(starWebServer.java:66)
        at IOxUnifiedSanityTestSuite.starWebServer$2.handle(starWebServer.java:148)
        at IOxUnifiedSanityTestSuite.starWebServer$2.handle(starWebServer.java:124)
        at io.vertx.ext.web.impl.RouteImpl.handleContext(RouteImpl.java:217)
        at io.vertx.ext.web.impl.RoutingContextImplBase.iterateNext(RoutingContextImplBase.java:78)
        at io.vertx.ext.web.impl.RoutingContextImpl.next(RoutingContextImpl.java:133)
        at io.vertx.ext.web.impl.RouterImpl.accept(RouterImpl.java:79)
        at io.vertx.core.http.impl.ServerConnection.handleRequest(ServerConnection.java:288)
        at io.vertx.core.http.impl.ServerConnection.processMessage(ServerConnection.java:421)
        at io.vertx.core.http.impl.ServerConnection.handleMessage(ServerConnection.java:134)
        at io.vertx.core.http.impl.HttpServerImpl$ServerHandler.doMessageReceived(HttpServerImpl.java:623)
        at io.vertx.core.http.impl.HttpServerImpl$ServerHandler.doMessageReceived(HttpServerImpl.java:573)
        at io.vertx.core.http.impl.VertxHttpHandler.lambda$channelRead$0(VertxHttpHandler.java:71)
        at io.vertx.core.impl.ContextImpl.lambda$wrapTask$2(ContextImpl.java:322)
        at io.vertx.core.impl.ContextImpl.executeFromIO(ContextImpl.java:190)
        at io.vertx.core.http.impl.VertxHttpHandler.channelRead(VertxHttpHandler.java:71)
        at io.vertx.core.net.impl.VertxHandler.channelRead(VertxHandler.java:122)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:349)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:341)
        at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:293)
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:267)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:349)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:341)
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1334)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:349)
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:926)
        at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:129)
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:642)
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:565)
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:479)
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:441)
        at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.IOException: error=2, No such file or directory
        at java.lang.UNIXProcess.forkAndExec(Native Method)
        at java.lang.UNIXProcess.<init>(UNIXProcess.java:248)
        at java.lang.ProcessImpl.start(ProcessImpl.java:134)
        at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
        ... 36 more


The way I am calling exec function is this:



    String command1[] = new String[]{"ifconfig | grep -A 1 \'eth0\' | tail -1 |cut -d \':\' -f 2 |cut -d \' \' -f 1"};
        StringBuilder stdout = new StringBuilder();
        StringBuilder stderr = new StringBuilder();
        exec(command1, null, stdout, stderr, 30)

    String command2[] = new String[]{"./executeTest.sh ipaddress"};
     StringBuilder stdout1 = new StringBuilder();
     StringBuilder stderr1 = new StringBuilder();
     exec(command2, null, stdout1, stderr1, 30)

Can anyone help me in finding out what I am doing wrong here?

Answer 1

You probably feed your first command as a whole to ProcessBuilder's constructor:

"ifconfig| grep -A 1 'eth0'|tail -1|cut -d ':' -f 2|cut -d ' ' -f 1"

ProcessBuilder considers it to be a single program name, hence the error.

Try passing it the following:

new String{"/bin/bash", "-c", "ifconfig| grep -A 1 'eth0'|tail -1|cut -d ':' -f 2|cut -d ' ' -f 1"}

like

exec(new String{"/bin/bash", "-c", "ifconfig| grep -A 1 'eth0'|tail -1|cut -d ':' -f 2|cut -d ' ' -f 1"},
    envt, stdout, stderr, timeoutSeconds);

ProcessBuilder will invoke bash, which in turn will invoke the complex command.