it's possible to get the output of a command inside linux shell to a JAVA app? if it's possible how? I see the chance to execute from JAVA a shell command i wish the opposite result : SHELL COMMANDS OUTPUT --->to---> Java VARIABLE or STRING. thanks for reply
3
-
Possible duplicate of How to run linux commands in java code?Suraj Rao– Suraj Rao2017-03-30 14:45:49 +00:00Commented Mar 30, 2017 at 14:45
-
suraj it's the opposite question not " How to run linux commands in java code? "Francesco Valla– Francesco Valla2017-03-30 14:51:48 +00:00Commented Mar 30, 2017 at 14:51
-
do u mean , you want to execute a command from java and get the output of that command to be stored in java varaiable?Monis Majeed– Monis Majeed2017-03-30 14:59:51 +00:00Commented Mar 30, 2017 at 14:59
Add a comment
|
3 Answers
You can use jcraft and then execute command which returns the output
Example
host = //your hostIP;
String user = "username";
String password = "pwd";
String command = "the command you want to execute";
try {
java.util.Properties config = new java.util.Properties();
config.put("StrictHostKeyChecking", "no");
JSch jsch = new JSch();
Session session = jsch.getSession(user, host, 22);
session.setPassword(password);
session.setConfig(config);
session.connect();
System.out.println("Connected");
Channel channel = session.openChannel("exec");
((ChannelExec) channel).setCommand(command);
channel.setInputStream(null);
((ChannelExec) channel).setErrStream(System.err);
InputStream in = channel.getInputStream();
channel.connect();
byte[] tmp = new byte[1024];
while (true) {
while (in.available() > 0) {
int i = in.read(tmp, 0, 1024);
if (i < 0)
break;
area.append(new String(tmp, 0, i));
//System.out.print(new String(tmp, 0, i)); //command output
}
if (channel.isClosed()) {
System.out.println("exit-status: " + channel.getExitStatus());
break;
}
try {
Thread.sleep(1000);
} catch (Exception ee) {
}
}
channel.disconnect();
session.disconnect();
System.out.println("DONE");
} catch (Exception e) {
e.printStackTrace();
return false;
}
Comments
Ok lets assume you want to run X command in linux.
then in the terminal type:
x > "myfilename"
Just to give an example:
netstat > "xyz"
This will create a file 'xyz' and transfer all the output to it.
This will put all the output to the 'myfilename'.
Now you can read all the contents of the file from a java application.
Alternative:
You can run shell command from java and collect the output for later processing.
Comments
1 Command line argument
Assuming you're trying to pass the output of a linux command to java when starting the java program, this is simple to do in bash. Use back-ticks (`) to surround the linux command in the place where you put command line arguments. E.g.:
$ java [... java options, like -jar path/to/file.jar ...] -- `linux-command`
(You may have to do some quotes or escaping of some sort if the output contains spaces.)
Then, in your java program, the value will be in the args array:
public static void main(String args[]) {
String linuxCommandOutput = args[0];
// rest of program...
}
2 System Property
If you can't use args for some reason, you can try to use system properties. Again, use back-ticks (`) to surround the linux command and store it in a system property with -D. Like so:
$ java -Dvariable=`linux-command` [... java options ...]
Then, in your java program, read the value of the system property:
public static void main(String args[]) {
String linuxCommandOutput = System.getProperty("variable");
// rest of program...
}
