I want to get total RAM on Android:
private String getTotalRAM()
{
ProcessBuilder cmd;
String result="";
try{
String[] args = {"/system/bin/sh", "-c", "cat -n /proc/meminfo | grep MemTotal"};
cmd = new ProcessBuilder(args);
Process process = cmd.start();
InputStream in = process.getInputStream();
byte[] re = new byte[1024];
while(in.read(re) != -1){
System.out.println(new String(re));
result = result + new String(re);
}
in.close();
} catch(IOException ex){
ex.printStackTrace();
}
return result;
}
If there are not grep MemTotal, cat returns me a whole info about memory. When I want to get just one line with grep, I get nothing. How can i fix this? I just want to get total available RAM at this moment.
All kinds of redirections (|, >, <, ...) are handled by the shell. If you don't invoke the shell, then you can't use those.
A clean solution would be to read /proc/meminfo in your Java code and simple search for the String MemTotal manually. The code wouldn't be much longer than what you're doing now and would need a lot less resurces.
As #Joachim suggests you are likely to find this works for you.
BufferedReader pmi = new BufferedReader(new FileReader("/proc/meminfo"));
try {
String line;
while ((line = pmi.readLine()) != null)
if (line.contains("MemTotal"))
// get the second word as a long.
return Long.parseLong(line.split(" +",3)[1]);
return -1;
} finally {
pmi.close();
}
Related
I'd like to know whether a certain application is in focus in Linux. Say it is Google Chrome. To do so, I wrote a bash on-liner which does it correctly.
xdotool search --name --class 'google-chrome' | grep $(xdotool getactivewindow)
When this command is run in terminal, it will print the id of the terminal itself. To avoid that, run the following command and select Chrome in the three seconds time span.
sleep 3; xdotool search --name --class 'google-chrome' | grep $(xdotool getactivewindow)
The problem is that when I run the above-mentioned one-liner from Java, it seems to always print nothing. Here's my code:
String cmd = "xdotool search --name --class 'google-chrome' | grep $(xdotool getactivewindow)";
Process p = Runtime.getRuntime().exec(cmd);
String result = getCommandResult(p.getInputStream());
private static String getCommandResult(InputStream stream) throws IOException {
StringBuilder sb = new StringBuilder();
try (InputStreamReader isr = new InputStreamReader(stream);
BufferedReader in = new BufferedReader(isr)) {
String line;
while ((line = in.readLine()) != null) {
sb.append(line);
}
}
return sb.toString().trim();
}
I'm open to different solutions to resolving this problem.
As barti_ddu said, this is not working because of the pipe in the command. You can workaround this by creating one sh process with your command passed as the argument:
String cmd = "xdotool search --name --class 'google-chrome' | grep $(xdotool getactivewindow)";
Process p = new ProcessBuilder("sh", "-c", cmd).start();
String result = getCommandResult(p.getInputStream());
If You are using pipe redirection, then You either have to invoke the shell, or redirect the output from one program to another yourself.
However, IMHO, You do not need grep at all, just:
Enumerate windows of certain class.
Get the active window id and check if the active window list contains it.
Example (q&d, resource/error handling omitted):
private static List<String> exec(String... args) throws IOException {
List<String> result = new ArrayList<>();
String line;
BufferedReader reader = new BufferedReader(
new InputStreamReader(
new ProcessBuilder()
.command(args)
.start()
.getInputStream()));
while ((line = reader.readLine()) != null) {
result.add(line);
}
return result;
}
public static void main(String[] args) {
try {
Thread.sleep(3000);
String windowId = exec("xdotool", "getactivewindow").get(0);
System.out.println(windowId);
List<String> windowList = exec("xdotool", "search", "--name", "--class", "google-chrome");
System.out.println(windowList.contains(windowId));
} catch (IOException | InterruptedException e) {
e.printStackTrace();
}
Why are you hard coding the command into your class? Rather put your command in a shell script and call that instead. Then you have the flexibility to change the command without having to re-compile.
Process proc = Runtime.getRuntime().exec("./opt/scripts/myscript.sh");
... depending on your application, it would potentially be even better to pass in the shell script as parameter.
private void runCommandLine(String script) {
try {
Process proc = Runtime.getRuntime().exec(script);
proc.waitFor();
int character;
while((character = proc.getInputStream().read()) != -1) {
System.out.write(character);
}
while((character = proc.getErrorStream().read()) != -1) {
System.err.write(character);
}
} catch (IOException | InterruptedException e) {
e.printStackTrace();
}
}
EDIT:
If you goal is to figure out what window is currently in focus, then instead of trying to execute something via the command line, you could just use the JNA (Java Native Access) libraries to potentially do this.
Find out what application (window) is in focus in Java
Java Native Access (Github)
Consider the following code:
String commandf = "ls /etc | grep release";
try {
// Execute the command and wait for it to complete
Process child = Runtime.getRuntime().exec(commandf);
child.waitFor();
// Print the first 16 bytes of its output
InputStream i = child.getInputStream();
byte[] b = new byte[16];
i.read(b, 0, b.length);
System.out.println(new String(b));
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
The program's output is:
/etc:
adduser.co
When I run from the shell, of course, it works as expected:
poundifdef#parker:~/rabbit_test$ ls /etc | grep release
lsb-release
The internets tell me that, due to the fact that pipe behavior isn't cross-platform, the brilliant minds who work in the Java factory producing Java can't guarantee that pipes work.
How can I do this?
I am not going to do all of my parsing using Java constructs rather than grep and sed, because if I want to change the language, I'll be forced to re-write my parsing code in that language, which is totally a no-go.
How can I make Java do piping and redirection when calling shell commands?
Write a script, and execute the script instead of separate commands.
Pipe is a part of the shell, so you can also do something like this:
String[] cmd = {
"/bin/sh",
"-c",
"ls /etc | grep release"
};
Process p = Runtime.getRuntime().exec(cmd);
I ran into a similar problem in Linux, except it was "ps -ef | grep someprocess".
At least with "ls" you have a language-independent (albeit slower) Java replacement. Eg.:
File f = new File("C:\\");
String[] files = f.listFiles(new File("/home/tihamer"));
for (String file : files) {
if (file.matches(.*some.*)) { System.out.println(file); }
}
With "ps", it's a bit harder, because Java doesn't seem to have an API for it.
I've heard that Sigar might be able to help us:
https://support.hyperic.com/display/SIGAR/Home
The simplest solution, however, (as pointed out by Kaj) is to execute the piped command as a string array. Here is the full code:
try {
String line;
String[] cmd = { "/bin/sh", "-c", "ps -ef | grep export" };
Process p = Runtime.getRuntime().exec(cmd);
BufferedReader in =
new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((line = in.readLine()) != null) {
System.out.println(line);
}
in.close();
} catch (Exception ex) {
ex.printStackTrace();
}
As to why the String array works with pipe, while a single string does not... it's one of the mysteries of the universe (especially if you haven't read the source code). I suspect that it's because when exec is given a single string, it parses it first (in a way that we don't like). In contrast, when exec is given a string array, it simply passes it on to the operating system without parsing it.
Actually, if we take time out of busy day and look at the source code
(at http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/lang/Runtime.java#Runtime.exec%28java.lang.String%2Cjava.lang.String[]%2Cjava.io.File%29), we find that is exactly what is happening:
public Process [More ...] exec(String command, String[] envp, File dir)
throws IOException {
if (command.length() == 0)
throw new IllegalArgumentException("Empty command");
StringTokenizer st = new StringTokenizer(command);
String[] cmdarray = new String[st.countTokens()];
for (int i = 0; st.hasMoreTokens(); i++)
cmdarray[i] = st.nextToken();
return exec(cmdarray, envp, dir);
}
Create a Runtime to run each of the process. Get the OutputStream from the first Runtime and copy it into the InputStream from the second one.
#Kaj accepted answer is for linux. This is the equivalent one for Windows:
String[] cmd = {
"cmd",
"/C",
"dir /B | findstr /R /C:"release""
};
Process p = Runtime.getRuntime().exec(cmd);
Consider the following code:
String commandf = "ls /etc | grep release";
try {
// Execute the command and wait for it to complete
Process child = Runtime.getRuntime().exec(commandf);
child.waitFor();
// Print the first 16 bytes of its output
InputStream i = child.getInputStream();
byte[] b = new byte[16];
i.read(b, 0, b.length);
System.out.println(new String(b));
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
The program's output is:
/etc:
adduser.co
When I run from the shell, of course, it works as expected:
poundifdef#parker:~/rabbit_test$ ls /etc | grep release
lsb-release
The internets tell me that, due to the fact that pipe behavior isn't cross-platform, the brilliant minds who work in the Java factory producing Java can't guarantee that pipes work.
How can I do this?
I am not going to do all of my parsing using Java constructs rather than grep and sed, because if I want to change the language, I'll be forced to re-write my parsing code in that language, which is totally a no-go.
How can I make Java do piping and redirection when calling shell commands?
Write a script, and execute the script instead of separate commands.
Pipe is a part of the shell, so you can also do something like this:
String[] cmd = {
"/bin/sh",
"-c",
"ls /etc | grep release"
};
Process p = Runtime.getRuntime().exec(cmd);
I ran into a similar problem in Linux, except it was "ps -ef | grep someprocess".
At least with "ls" you have a language-independent (albeit slower) Java replacement. Eg.:
File f = new File("C:\\");
String[] files = f.listFiles(new File("/home/tihamer"));
for (String file : files) {
if (file.matches(.*some.*)) { System.out.println(file); }
}
With "ps", it's a bit harder, because Java doesn't seem to have an API for it.
I've heard that Sigar might be able to help us:
https://support.hyperic.com/display/SIGAR/Home
The simplest solution, however, (as pointed out by Kaj) is to execute the piped command as a string array. Here is the full code:
try {
String line;
String[] cmd = { "/bin/sh", "-c", "ps -ef | grep export" };
Process p = Runtime.getRuntime().exec(cmd);
BufferedReader in =
new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((line = in.readLine()) != null) {
System.out.println(line);
}
in.close();
} catch (Exception ex) {
ex.printStackTrace();
}
As to why the String array works with pipe, while a single string does not... it's one of the mysteries of the universe (especially if you haven't read the source code). I suspect that it's because when exec is given a single string, it parses it first (in a way that we don't like). In contrast, when exec is given a string array, it simply passes it on to the operating system without parsing it.
Actually, if we take time out of busy day and look at the source code
(at http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/lang/Runtime.java#Runtime.exec%28java.lang.String%2Cjava.lang.String[]%2Cjava.io.File%29), we find that is exactly what is happening:
public Process [More ...] exec(String command, String[] envp, File dir)
throws IOException {
if (command.length() == 0)
throw new IllegalArgumentException("Empty command");
StringTokenizer st = new StringTokenizer(command);
String[] cmdarray = new String[st.countTokens()];
for (int i = 0; st.hasMoreTokens(); i++)
cmdarray[i] = st.nextToken();
return exec(cmdarray, envp, dir);
}
Create a Runtime to run each of the process. Get the OutputStream from the first Runtime and copy it into the InputStream from the second one.
#Kaj accepted answer is for linux. This is the equivalent one for Windows:
String[] cmd = {
"cmd",
"/C",
"dir /B | findstr /R /C:"release""
};
Process p = Runtime.getRuntime().exec(cmd);
Here is the snapshot what I want exately!
I am trying to develop a program in java which can get all opened application in the taskbar. I have tried many links but none of those are helpful to me. The same question was also asked by Ganesh Rangarajan in July 2013 but none has answered him. Here is his question.
Here is the solution to get titles of ALL (visible, non-visible) windows:
https://stackoverflow.com/a/11067492/6401177
If you want to get titles of opened top-level windows only (i.e. Applications taskbar), you have to check the visibility of each window (and/or check other conditions as listed here: http://vb.mvps.org/articles/ap200003.asp). Although, checking window's visibility seems sufficient.
I just altered method "callback" in previous code like this:
String wText = Native.toString(windowText, System.getProperty("file.encoding")).trim();
com.sun.jna.platform.win32.WinDef.HWND hwnd_1 = new WinDef.HWND(hWnd);
boolean b = com.sun.jna.platform.win32.User32.INSTANCE.IsWindowVisible(hwnd_1);
if (!wText.isEmpty() && b) {
windowNames.add(wText);
}
I also added "file.encoding" so titles are shown correctly in non-english Windows environment too.
I tested code in Windows XP/7/8 and it works nice.
The only problem seems to be that some default internal(?) window called "Program Manager" is always included in the list.
You need both JARs (JNA libraries) from: https://github.com/java-native-access/jna
This reply is too late for you, but may help someone else who is now facing a similar issue.
I just wrote a similar applications to do it but to opened CMD only
and you can replace the listCommand by
powershell -command "get-Process | format-table mainwindowtitle"
(takig care with \ to use it in java) to get all opened applications .
public String[] getEnginesFromTaskManger()
{
// listCommand is a command to get all opened CMD program like (batches,.......)
// you can test it in your CMD as powershell -command "get-Process cmd | format-table mainwindowtitle"
String listCommand = "powershell -command \"get-Process cmd | format-table mainwindowtitle\"";
try
{
String line;
// since line length for powershell output is 79
int outLen = 79;
Process p = Runtime.getRuntime().exec(listCommand);
BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
line = input.readLine();
System.out.println("line: " + line + "\t" + line.length());
EnginesListFromTaskManeger = new ArrayList<String>();
int i = 0;
/*
I used this outLen > 0 condition to make sure that this method will close automatically
in case of no running CMD applications and you running this from your IDE's (Eclipse, Netbeans , ......)
the powershell will not stopped so i used it. */
while(line != null && outLen > 0)
{
System.out.println("line: " + line + "\t" + line.length());
line = input.readLine().trim().toLowerCase();
outLen = line.length();
EnginesListFromTaskManeger.add(i, line);
System.out.println(EnginesListFromTaskManeger.get(i));
// EnginesListFromTaskManeger[i]=(String)input.readLine().trim();
// System.out.println("EnginesListFromTaskManeger"+ EnginesListFromTaskManeger[i]);
i++;
}
input.close();
}catch(Exception err)
{
err.printStackTrace();
}
ListFromTaskManeger = new String[EnginesListFromTaskManeger.size()];
ListFromTaskManeger = EnginesListFromTaskManeger.toArray(ListFromTaskManeger);
return ListFromTaskManeger;
}
The process list from the command "ps -e":
try {
String line;
Process p = Runtime.getRuntime().exec("ps -e");
BufferedReader input =
new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((line = input.readLine()) != null) {
System.out.println(line); //<-- Parse data here.
}
input.close();
} catch (Exception err) {
err.printStackTrace();
}
In windows see following used following code
Process p = Runtime.getRuntime().exec
(System.getenv("windir") +"\\system32\\"+"tasklist.exe");
Hope the info help!
"tasklist.exe /nh /v" worked perfectly to get the running applications.
try {
Process p = Runtime.getRuntime().exec("tasklist.exe /nh /v");
BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((String line = input.readLine()) != null) {
System.out.println(line); //<-- Parse data here.
}
input.close();
} catch (Exception err) {
err.printStackTrace();
}
Is there a way to get an output from a shell script program into a variable in Java program(not into the output file). The output of my shell script is the database query execution time and I need to assign that time value to a Java variable. (I am calling that shell script from Java program). And then I will need to do some other calculations on those values in Java.
Update to old question
Since Java 7 there is a new class which can easily deal with OS procecces: ProcessBuilder
.Let's assume we need to store the output of ip_conf.bat into a java String. Contents of c:\tmp\ip_conf.bat
#echo off
REM will go to standard output
ipconfig
REM will go to stadnard error
hey there!
You can read the input streams connected to the standard and error outputs of the subprocess:
ProcessBuilder pb = new ProcessBuilder("C:\\tmp\\ip_conf.bat");
Process p = pb.start();
String pOut = "";
try (InputStream stdOut = p.getInputStream();
BufferedInputStream bufferedStdOut = new BufferedInputStream(stdOut);
ByteArrayOutputStream result = new ByteArrayOutputStream()) {
int bytes = 0;
while ((bytes = bufferedStdOut.read()) != -1) {
result.write(bytes);
}
pOut = result.toString(Charset.defaultCharset().toString());
}
System.out.println(pOut);
InputStream stdErr = p.getErrorStream();
// same with the error stream ...
int exit = p.waitFor();
System.out.println("Subprocess exited with " + exit);
Below is the program that will help you store the full output of any script or any command into String object.
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class ExecuteShellComand {
public static void main(String[] args) {
ExecuteShellComand obj = new ExecuteShellComand();
String output = obj.executeCommand("sh /opt/yourScriptLocation/Script.sh");
System.out.println(output);
}
private String executeCommand(String command) {
StringBuffer output = new StringBuffer();
Process p;
try {
p = Runtime.getRuntime().exec(command);
p.waitFor();
BufferedReader reader =
new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = "";
while ((line = reader.readLine())!= null) {
output.append(line + "\n");
}
} catch (Exception e) {
e.printStackTrace();
}
return output.toString();
}
}
I just google it and there is a nice tutorial, full of examples here : http://www.mkyong.com/java/how-to-execute-shell-command-from-java/
I know people prefere copy/paste but let's respect other people's work and go on their website :p