Reputation: 41823
I need to wrap the Unix command "tail -f" in a BufferedInputStream. I don't want to simulate or mimic tail as stated by this question. Rather, I want to use tail, waiting for it to give me a new line.
Upvotes: 3
Views: 5814
Reputation: 17375
Two more full blown projects:
http://www.eclipse.org/tptp/home/documents/tutorials/gla/gettingstarted_gla.html
http://commons.apache.org/io/api-release/org/apache/commons/io/input/Tailer.html
Upvotes: 0
Reputation: 116352
check also ProcessBuilder:
Process tail = new ProcessBuilder("tail", "-f", file).start();
BufferedInputStream bis = new BufferedInputStream(tail.getInputStream())
where file
is String like "/var/log/messages".
Upvotes: 1
Reputation: 1408
Your best bet is to use the Process
class and read with a Scanner
:
Runtime r = Runtime.getRuntime()
Process p = r.exec("tail -f")
Scanner s = new Scanner(p.getInputStream())
while (s.hasNextLine()) {
String line = s.nextLine()
// Do whatever you want with the output.
}
hasNextLine()
should block as it's waiting for more input from the input stream, so you will not be busy-waiting as data comes in.
Upvotes: 14
Reputation: 26291
If you have the unix command
tail -f <file> | <some java program>
Then the tail would appear as an InputStream
that may block for a period of time. If you don't want to block yourself, you would use the nio packages. I believe that most other ways to access the tail command (such as Process
) results in a similar InputStream
.
Upvotes: 0
Reputation: 3573
I am guessing that system() and popen() type approaches will not work as they will block your program until the tail command terminates.
I think you could redirect the output to a file and use 'diff' against the last version to see which lines are new?
Upvotes: 0
Reputation: 9855
Look at Runtime.exec(String command). Returns a Process object that has Input and Output Streams.
Upvotes: 1