I have the following java code
ArrayList<String> argList = new ArrayList<>();
argList.add("Hello");
argList.add("World");
String[] args = argList.toArray(new String[argList.size()]);
Process p =Runtime.getRuntime().exec("echo '$1 $2' ", args);
result is $1 $2 but i want to print Hello World.
Can anybody help me?
Create a shell to use the parameter expansion:
ArrayList<String> command = new ArrayList<>();
command.add("bash");
command.add("-c");
command.add("echo \"$0\" \"$1\"");
command.addAll(argList);
Process p = Runtime.getRuntime().exec(command.toArray(new String[1]));
Output:
Hello World
You should use the exec(String[] args) method, instead:
String[] cmdArgs = { "echo", "Hello", "World!" };
Process process = Runtime.getRuntime().exec(cmdArgs);
BufferedReader in = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line = null;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
The problem is, that the first argument in the exec() method is not the script, but the name of the script.
If you want to use variables, like $1 and $2 you should do that in your script.
So, what you actually might want is:
String[] cmdArgs = { "myscript", "Hello", "World!" };
Process process = Runtime.getRuntime().exec(cmdArgs);
ArrayList<String> argList = new ArrayList<>();
argList.add("echo");
argList.add("Hello");
argList.add("World");
Process p =Runtime.getRuntime().exec(args);
This way the String[] will be passed as an argument to echo.
If you want to use $ then you will have to write a shell script.
Echo will print all arguments as such. In your case '$1 $2' is interpreted as normal string.. Since it will anyway print all args you could use some thing like below.
ProcessBuilder pb= new ProcessBuilder().command("/bin/echo.exe", "hello", "world\n");
Another option is co create a small script say mycommands.sh with appropriate contents
echo $@
echo $1 $2
#any such
You then invoke your script... like
ProcessBuilder pb= new ProcessBuilder().command("/bin/bash" , "-c", "<path to script > ", "hello", "world\n");
Note the use of ProcessBuilder. This is an improved api instead of Runtime.(especially for quoting etc)
argsnotargList.