Process log_remover = Runtime.getRuntime().exec("echo \"bleh\" > test.txt");
log_remover.waitFor();
log_remover.destroy();
this does nothing
Process node_creation = Runtime.getRuntime().exec("cp -r ../HLR"+String.valueOf(count-1)+" ../HLR"+String.valueOf(count));
node_creation.waitFor();
node_creation.destroy();
however this works :S
The redirection works only if a shell is used. Runtime.exec() does not use a shell.
Redirection is handled by a shell, and you're not invoking a shell here, so you can't use redirection. Something like this, on the other hand, would work:
Runtime.getRuntime().exec(new String[] {"sh", "-c", "echo 'bleh' > text.txt"});
Note I've changed this to use the form of exec() that takes an array of Strings, as properly tokenizing quoted strings on a command line is something else that only the shell can do!
log_remover.sh executable? Is it on your PATH ?Classic mistake I've seen many times before...
The first argument to Runtime.getRuntime().exec() is the executable, so your code is trying to execute a command literally called echo \"bleh\" > test.txt, but it should be trying to execute echo. Arguments to executables are passed in after the executable, like this:
Runtime.getRuntime().exec("echo", new String[]{"bleh"});
Redirecting output is another story, because the *nix operator > is a shell thing. To replicate this in java you have to get the outputstream of the command and pump it to the inputstream of another process
Runtime.getRuntime().exec("/usr/bin/log_remover.sh") or whatever it is. The java exec environment isn't the same as your shell.