Question

So, first things first, we cannot use the javax print services because it is extremely slow as we have more than 20,000 printers installed on a machine (the lookup uses lpstat which is incredibly slow). So, we’re using lpr.

When I do this:

cat myfile.pdf | lpr -P "MyPrinter"

it prints the file perfectly to the printer name MyPrinter. To do the same in Java, I’m doing this:

cmd = String.format("lpr -P \"%s\"", "MyPrinter");

Process p = Runtime.getRuntime().exec(cmd);

OutputStream out = p.getOutputStream();

/*
 This essentially runs a thread which reads from a stream and
 outputs it to the STDOUT. This is what I've written to help with
 debugging
*/
StreamRedirect inRed = new StreamRedirect(p.getInputStream(), "IN");
StreamRedirect erRed = new StreamRedirect(p.getErrorStream(), "ER");

inRed.start();
erRed.start();


/*
 This is where I write to lprs STDIN. `document` is an InputStream
*/

final byte buf[] = new byte[1024];
int len;

while((len = document.read(buf)) > 0) {
    out.write(buf, 0, len);
}

out.flush();
out.close();

But, I get the following error:

SR[ER]>>lpr: The printer or class was not found.

Here, SR[ER] is just a custom label that is prefixed by the StreamRedirect. Why is this happening? Why is it able to find a printer when I run it from my command line, but not otherwise?

Also, I tried to run whoami from within the Java program and it says that I am running it as the same user I am logged in as (the same user with which I execute lpr on the command line).

Any help?

Answer 1

You need to put the command and the arguments in a string array

String[] cmd = new String[] { "lpr" , "-P", "MyPrinter" };

Process p = Runtime.getRuntime().exec(cmd);

You might also want to use the newer ProcessBuilder class.