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this is the code I am using to back up my database using pg_dump 9.3 in java. The problem I have is that always the result file is empty, and the exit code is 1, any ideas?

public static void backupDb() throws IOException, InterruptedException {
    Runtime rt = Runtime.getRuntime();
    Process p;
    ProcessBuilder pb;
    rt = Runtime.getRuntime();
    pb = new ProcessBuilder(
            "C:\\Program Files\\PostgreSQL\\9.3\\bin\\pg_dumpall.exe",
            "--host", "localhost",
            "--port", "5432",
            "--username", "postgres",
            "--no-password",
            "--format", "custom",
            "--blobs",
            "--verbose", "--file", "D:\\service_station_backup.backup", "service_station");
    p = pb.start();
    p.waitFor();
    System.out.println(p.exitValue());
                Does the process / app have write access to the file location @Abdelwahhab ? Eg what is the user id of the process and does the user id have access to the output file?
– user1123335
                May 3, 2016 at 3:53
                @pnorton yes, the process can access the output file, the file is correctly created, but not content is dumped into it. i think the problem is with postgres server password.
– Wolverine219
                May 3, 2016 at 8:46
                Hi @no_pain_no_gain what does the postgresql log say  (show log_destination ;  log_destination  -----------------  stderr (1 row)  so for me its syslogs )? (journalctl |grep [Pp]ostgres |more ) You might need to turn up the logging. Could you show the contents of pg_hba.conf I might be able to help REF postgresql.org/docs/9.1/static/auth-pg-hba-conf.html
– user1123335
                May 3, 2016 at 15:35
thanks everyone for help, finally could find the perfect code.
public static void exportDb2() throws IOException, InterruptedException {
    Runtime rt = Runtime.getRuntime();
    Process p;
    ProcessBuilder pb;
    rt = Runtime.getRuntime();
    pb = new ProcessBuilder(
            "C:\\Program Files\\PostgreSQL\\9.3\\bin\\pg_dump.exe",
            "--host", "localhost",
            "--port", "5432",
            "--username", "postgres",
            "--no-password",
            "--format", "custom",
            "--blobs",
            "--verbose", "--file", "D:\\service_station_backup.backup", "service_station");
    try {
        final Map<String, String> env = pb.environment();
        env.put("PGPASSWORD", "admin");
        p = pb.start();
        final BufferedReader r = new BufferedReader(
                new InputStreamReader(p.getErrorStream()));
        String line = r.readLine();
        while (line != null) {
            System.err.println(line);
            line = r.readLine();
        r.close();
        p.waitFor();
        System.out.println(p.exitValue());
    } catch (IOException | InterruptedException e) {
        System.out.println(e.getMessage());
For psql, the "long options" need an equal sign: =. So it needs to be e.g. --host=localhost. For that you need to pass those arguments as a single String argument to ProcessBuilder:
pb = new ProcessBuilder(
        "C:\\Program Files\\PostgreSQL\\9.3\\bin\\pg_dumpall.exe",
        "--host=localhost",
        "--port=5432",
        "--username=postgres",
        "--no-password",
        "--format=custom",
        "--blobs",
        "--verbose", "--file=D:\\service_station_backup.backup", "service_station");
You should also capture the error output of the ProcessBuilder using ProcessBuilder.getErrorStream() to see any error message from psql. You probably want to capture the regular output as well (using getInputStream()) 
The error message you get: 
  
fe_sendauth: no password supplied
means you have to provide a password. 
You can do that by passing a connection URL to pg_dump. 
pb = new ProcessBuilder(
        "C:\\Program Files\\PostgreSQL\\9.3\\bin\\pg_dumpall.exe",
        "--dbname=postgres://postgres:password@localhost/postgres",
        "--format=custom",
        "--blobs",
        "--verbose", "--file=D:\\service_station_backup.backup", "service_station");
                hi, thanks for following,i tried what you advised but still get the same result, and the same  message from the process ErrorStream : " fe_sendauth: no password supplied".
– Wolverine219
                May 3, 2016 at 8:36
                Then you need to provide a password. Either by setting the PGPASSWORD environment variable, by configuring it in pgpass.conf or by providing a connection URL. See the manual for details: postgresql.org/docs/9.3/static/libpq-connect.html#AEN39257
– user330315
                May 3, 2016 at 8:40
        
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