I am running sed command in java program when i execute my java file in linux.
when i ran the command alone in linux, this will work -> sed '1d;$d' /home/sample/testdata.txt > /home/output/testupdate.txt
however when i ran my java program in linux, its returning exit(1) error . i have read through and use as an array but its still failing .
public static void main(String[] args) {
String[] cmd = {"sed", "sed '1d;$d' /home/sample/testdata.txt > /home/output/testupdate.txt"};
String s;
Process p;
try {
p = Runtime.getRuntime().exec(cmd);
BufferedReader br = new BufferedReader(
new InputStreamReader(p.getInputStream()));
while ((s = br.readLine()) != null) {
System.out.println("line: " + s);
}
p.waitFor();
System.out.println("exit: " + p.exitValue());
p.destroy();
} catch (Exception e) {
}
}
Java is not a shell so does not handle redirects - your original command only works via your Linux shell which understands ">".
You can make Java launch the shell to execute the command, say if you are using bash:
String[] cmd = {"/bin/bash", "-c"
, "sed '1d;$d' /home/sample/testdata.txt > /home/output/testupdate.txt"};
Alternatively see the other helpful comments which link to other pages on dealing with the redirects within the Java code, or to do it inside Java itself (such as with Files.lines / streams).
You don’t need sed. Java can do everything sed can do.
In your case, it appears you are using sed to remove the first and last line from a file. Here’s how you would do that in Java:
Path source = Path.of("/home/sample/testdata.txt");
Path destination = Path.of("/home/output/testupdate.txt");
long lineCount;
try (Stream<?> lines = Files.lines(source)) {
lineCount = lines.count();
}
long lastLine = lineCount - 1;
try (BufferedReader in = Files.newBufferedReader(source);
BufferedReader out = Files.newBufferedWriter(destination)) {
// Skip first line
String line = in.readLine();
long counter = 0;
while ((line = in.readLine()) != null) {
if (++counter < lastLine) {
out.write(line);
out.newLine();
}
}
}
If for some reason you absolutely need to use an external process, there are many other questions and answers which cover your mistake: > is not understood by sed. Normally, it is the shell (like bash) which interprets file redirection.
The proper way to run your command would have been:
ProcessBuilder builder =
new ProcessBuilder("sed", "1d;$d", "/home/sample/testdata.txt");
builder.redirectOutput(new File("/home/output/testupdate.txt"));
builder.redirectError(ProcessBuilder.Redirect.INHERIT);
Process p = builder.start();
Related
String str;
Process p;
try {
String command = "wmctrl -l|awk '{$1=\"\"; $2=\"\"; $3=\"\"; print}'";
p = Runtime.getRuntime().exec(command);
BufferedReader br = new BufferedReader(
new InputStreamReader(p.getInputStream()));
while ((str = br.readLine()) != null) {
activeWindowtitles.add(str);
System.out.println(str);
}
p.waitFor();
p.destroy();
} catch (Exception ex) {
}
I am writing a java code to get all applications name in Linux system. I found a command to achieve this. I ran this command in Terminal and it works fine. But it is not working in Java code as i want only applications name instead of other details. The command is "wmctrl -l | awk '{$1=""; $2=""; $3=""; print}'"
I am getting full output after executing this in java code.
Please tell me how to write this command properly..
Thanks
Personally I would put the wmctrl command in a script and do something like this:
public static List<String> getRunningApps(String executablePath) throws IOException, InterruptedException {
final String ERR_LOG_PATH = "stderr.log";
List<String> result = new ArrayList<>();
ProcessBuilder pb = new ProcessBuilder(executablePath);
pb.redirectError(new File(ERR_LOG_PATH));
Process p = pb.start();
int exitCode = p.waitFor();
if (exitCode != 0) {
throw new RuntimeException(String.format("Error get apps. Check error log %s%n", ERR_LOG_PATH));
}
try (Scanner s = new Scanner(p.getInputStream())) {
while (s.hasNextLine()) {
result.add(s.nextLine().trim());
}
}
return result;
}
That way you can tweak it more easily and keep your code cleaner. The script I used was:
#!/bin/bash
wmctrl -l | awk '{$1=""; $2=""; $3=""; print}'
We can use Jython to implement python in java, but I dont want to go for that approach, what I am looking for is using command line utility and fire python command to execute the code and get the console output in java code.
python Main.py < input.txt
I used above command in terminal, it works there, giving me output, but unable to get the output in java code.
Note: Main.py and input.txt and java code in the same folder
What I am doing wrong in java code?
Here is Sample java code which I am calling in order to execute external python code
try {
Process process = Runtime.getRuntime()
.exec("python Main.py < input.txt");
process.waitFor();
System.out.println(process);
StringBuilder output
= new StringBuilder();
BufferedReader reader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
output.append(line + "\n");
}
System.out.println("here");
int exitVal = process.waitFor();
if (exitVal == 0) {
System.out.println("Success!");
System.out.println(output);
} else {
System.out.println("Process failed");
}
} catch (Exception e) {
// TODO: handle exception
System.out.println(e);
}
Here is a sample python code:
x = input();
y = input();
print(type(x));
print(type(y));
print(x + y);
here is a sample input file which I am passing as a input to the python code
30
40
As sandip showed, executing a command in java is not the same as running commands through BASH.
At first I tried to execute
bash -c "python Main.py < input.txt" (through java).
For some reason this didn't work, and even if it did its not a great solution as its dependent on the system its running on.
The solution I found to work was by using ProcessBuilder to first make the command, and redirect its input to a file. This allows you to keep the python code unchanged, and for me at least, give the same result as just running the BASH command.
Example:
ProcessBuilder pb = new ProcessBuilder("python3","Main.py");
//Make sure to split up the command and the arguments, this includes options
//I only have python3 on my system, but that shouldn't affect anything
pb.redirectInput(new File("./input.txt"));
System.out.println(pb.command());
Process process = pb.start();
//The rest is the exact same as the code in the question
Heres the ProcessBuilder docs for quick reference
java process not accept < symbol to input file in python command.
Instead you can run like this
python file
f = open("input.txt", "r")
for x in f:
print(type(x));
print(x)
java file
Process process = Runtime.getRuntime().exec("python Main.py input.txt");
process.waitFor();
System.out.println(process);
StringBuilder output
= new StringBuilder();
BufferedReader reader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
output.append(line + "\n");
}
System.out.println("here");
int exitVal = process.waitFor();
if (exitVal == 0) {
System.out.println("Success!");
System.out.println(output);
} else {
System.out.println("Process failed");
}
} catch (Exception e) {
// TODO: handle exception
System.out.println(e);
}
and use and same text file.
It should print in console
I am executing grep command from java on a linux file. Its always returning null for the following code.
Process p;
String matchStr="testmatch";
String output = null;
try {
String command = "grep \""+matchStr+"\" "+ filename;
System.out.println("Running command: " + command);
p = Runtime.getRuntime().exec(command);
System.out.println("***********************************");
System.out.println("***********************************");
System.out.println("***********************************");
p.waitFor();
BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
while (br.readLine() != null) {
System.out.println("in while loop");
System.out.println("in while loop");
System.out.println("in while loop");
System.out.println(output);
System.out.println("***********************************");
System.out.println("***********************************");
System.out.println("***********************************");
System.out.println("***********************************");
// Process your output here
}
System.out.println("exit: " + p.exitValue());
p.destroy();
} catch (Exception e) {
e.printStackTrace();
}
If i grep it directly it shows output but from java it never gets into while loop.
Please suggest whats wrong here.
The problem is that you do not write anything to output so it stays null. I guess you have to rewrite your while loop like this
while ((output = br.readLine()) != null) {
// Process your output here
}
Take a note that this syntax is discouraged by most style check due to it's abmiguity
Also it's a good idea to place p.waitFor() after while loop so grep would not hang on flushig std(err|out).
UPDATE
Also it is a good idea to use ProcessBuilder (available since java-7) instead of Runtime.getRuntime().exec(...) because you will have more control over the process i.e
final ProcessBuilder builder = new ProcessBuilder();
builder.command("grep", matchStr, filename);
// redirect stderr to stdout
builder.redirectErrorStream(true);
final Process process = builder.start();
BufferedReader br = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String output = null;
while ((output = br.readLine()) != null) {
System.out.println(output);
// Process your output here
}
process.waitFor();
After turning your code into a https://stackoverflow.com/help/mcve it works for me.
Here the file does not exist:
robert#habanero:~$ rm /home/robert/greptest.txt
robert#habanero:~$ javac GrepTest.java && java GrepTest
Running command: grep test /home/robert/greptest.txt
exit: 2
Now the file does exist but does not contain the text to be found:
robert#habanero:~$ echo not found > /home/robert/greptest.txt
robert#habanero:~$ javac GrepTest.java && java GrepTest
Running command: grep test /home/robert/greptest.txt
exit: 1
Now the file exists and contains the text:
robert#habanero:~$ echo test this > /home/robert/greptest.txt
robert#habanero:~$ javac GrepTest.java && java GrepTest
Running command: grep test /home/robert/greptest.txt
test this
exit: 0
Here is the code:
import java.io.*;
public class GrepTest {
public static void main(String[] args) throws Exception {
String command = "grep test /home/robert/greptest.txt";
System.out.println("Running command: " + command);
Process p = Runtime.getRuntime().exec(command);
p.waitFor();
BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
String output;
while ((output = br.readLine()) != null) {
System.out.println(output);
}
System.out.println("exit: " + p.exitValue());
p.destroy();
}
}
I was recently struggling with a similar issue, and I believe I the solution I found is an answer also to your problem (though your question is a bit malformed as others have pointed out).
The issue pertrains to the quote marks around your search string,
\""+matchStr+"\"
The java exec command will literally deliver these to the grep command, and instead of searching for matchStr, grep will be looking for "matchStr", and the results will not be what you are expecting.
This applies also in case one is executing the command as an array like
final Process process = Runtime.getRuntime().exec(new String[] { "grep", "-C1000", searchString, fileName } );
Pass the plain searchString without including quotation marks into the string.
I have this bash:
#!/bin/bash
# File to be tagged
inputfile="/dfs/sina/SinaGolestanirad-Project-OneTextEachTime/SinaGolestanirad-Project/Text.txt"
#inputfile="test/SampleInputs/longParagraph.txt"
# Tagged file to be created
#outputfile="test/SampleOutputs/NERTest.conll.tagged.txt"
outputfile="/dfs/sina/SinaGolestanirad-Project-OneTextEachTime/SinaGolestanirad-Project/1.Generate-Basic-Questions/Tagged-Named-Entites-Text.txt"
# Config file
#configfile="config/conll.config"
configfile="config/ontonotes.config"
# Classpath
cpath="target/classes:target/dependency/*"
CMD="java -classpath ${cpath} -Xmx8g edu.illinois.cs.cogcomp.LbjNer.LbjTagger.NerTagger -annotate ${inputfile} ${outputfile} ${configfile}"
echo "$0: running command '$CMD'..."
$CMD
When I run either java codes below they do not give any errors but they just show the bash file in my Eclipse Console, in other words they do not run the bash !! and the value for process.exitValue() is 1, by the way, my OS is CentOS, linux.
Firs JAVA code :
try {
Process process = new ProcessBuilder(command).start();
process.waitFor();
System.out.println(process.exitValue());
BufferedReader buf = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line = "";
while ((line = buf.readLine()) != null) {
System.out.println("exec response: " + line);
}
} catch (Exception e) {
System.out.println(e);
}
Second JAVA code :
String command = "/dfs/sina/SinaGolestanirad-Project-OneTextEachTime/"
+ "SinaGolestanirad-Project/1.Generate-Basic-Questions/1.IllinoisNerExtended-DO-NOT-OPEN-BY-ECLIPSE/plaintextannotate-linux.sh";
StringBuffer output = new StringBuffer();
Process p;
try {
String[] cmd = new String[]{"/bin/bash",command};
p = Runtime.getRuntime().exec(cmd);
p.waitFor();
BufferedReader reader = new BufferedReader(new InputStreamReader(
p.getInputStream()));
String line = "";
while ((line = reader.readLine()) != null) {
output.append(line + "\n");
}
System.out.println(output.toString());
} catch (Exception e) {
e.printStackTrace();
}
I also checked the bash file permission and it is executable as a program.
How can I run the bash file? The bash should run another program written in java.
-- LeBarton what is the exit code?
Check the output of p.exitValue()
p.waitFor()
InputStreamReader inputStreamReader = new InputStreamReader(p.getErrorStream());
While (inputStreamReader.ready()) { System.out.println(inputStreamReader.read(); }
This will show you the error output. Add this to the bottom below the try.. catch.
You will see the output that you would see on the command line. It will help you narrow down the error.
I found a link which may help, if your bash read some environmental variables.
$PATH variable isn't inherited through getRuntime().exec
I've been trying to make it where I can download a .exe file from the web, read it, and write it to a file locally, and then execute.
URL url = new URL("http://www.ddlands.com/downloads/Calc.exe");
URLConnection c = url.openConnection();
BufferedReader br = new BufferedReader(new InputStreamReader(c.getInputStream()));
String line = "";
File file = new File("analbread"+".exe");
BufferedWriter bw = new BufferedWriter(new FileWriter(file));
while((line = br.readLine()) != null){
bw.write(line + "\n");
}
br.close();
bw.close();
Process r = Runtime.getRuntime().exec("analbread" + ".exe");
System.out.println(r.toString());
System.out.println("WORKS!");
Although I know that doesn't work due to using BufferedWriter, and i'm not sure if it runs the exe.
For the downloading part, you'll need to use binary read/write. See this for further details: Working unbuffered streams.
For the executing part, the problem is that the Runtime.exec()-method can't launch your executable file.
At least under Linux (I can't test it on Windows), you'll need the full path to the executable file (or use ./[file] when the file is in the same directory as your application) to be able to execute it.
Only giving the command works for executables which are part of your systems PATH-variable.
Have a look at ClickOnce: http://en.wikipedia.org/wiki/ClickOnce
We've used that succesfully.
Ive used the following with good results to run command line scripts. You can create a batch script that runs the executable or run it directly using the exec method - probably pass "cmd ". This opens a command prompt from which you can run anything.
public static void runScript(String batchFile, boolean waitForExit0, int retryTime)
{
try
{
String runString = "cmd /c start " + (waitForExit0?"/wait ":"") + "/MIN " + batchFile;
Process p = Runtime.getRuntime().exec(runString); // /c start /wait
while (true)
{
try
{
int exit = p.exitValue();
if (exit == 0)
{
System.out.println("completed: " + runString);
return;
}
}
catch(Exception e)
{
String s = "";
}
Thread.sleep(retryTime);
}
}
catch(Exception e)
{
String s = "";
}
}