trying to execute mysqldump from java app, multiple problems

Question

I am writing a java app that needs to perform mysql dump, and I am using the runtime.exec, based in the when runtime.exec won't article. The code is below:

public int exectuteCommand(){
    Runtime rt = Runtime.getRuntime();
    logger.debug("exexuting cmd: " + showCommand());
    int exit = -1;
    try {
        Process proc = rt.exec(cmd);

        ExtProcessStreamHandler errorHandler = new ExtProcessStreamHandler(proc.getErrorStream(), "ERROR");
        ExtProcessStreamHandler outHandler = new ExtProcessStreamHandler(proc.getInputStream(), "OUTPUT");

        // kick it off
        errorHandler.start();
        outHandler.start();
        exit = proc.waitFor();

    } catch (IOException e) {
        logger.error("ERROR!! ~~ executing command " + showCommand(), e);
        e.printStackTrace();
    } catch (InterruptedException e) {
        logger.error("ERROR!! ~~ unexpected return for " + showCommand() + " , returned " + exit, e);
        e.printStackTrace();
    }

    return exit;
}

1) The command that the process returns works in the shell (I'm running this on a mac). The first error I had was an inability to find the mysqldump command. That results in this error:

java.io.IOException: Cannot run program "mysqldump": error=2, No such file or directory

I resolved that by adding the complete path of the file to the command. The $PATH var shows

/usr/local/mysql/bin/mysqldump

as the complete path. How can I make sure my java app has that info?

2) when adding the complete path to the command, I get this error msg:

 INFO [Thread-1] (ExtProcessStreamHandler.java:28) - external process ERROR : mysqldump: Couldn't find table: ">"

Here is the code that builds the command array:

return new String[] {MYSQLDUMP_CMD, "-u", USER_DEFAULT, "-p"+ PW_DEFAULT, TEST_DB_NAME,
            ">", DUMP_LOC};

again, when I copy the command passed to the java app into the shell on my mac, it works. Not sure what I'm doing wrong. thanks in advance!

Toddius Zho · Accepted Answer · 2013-07-10 19:34:56Z

2

It thinks ">" is an argument intended for mysqldump. You are invoking an executable, not evaluating a shell expression. If you want to pipe your output, do it with the outHandler and errorHandler in your code.

An alternative is to invoke a shell and pass the expression you want to evaluate as an argument:

expr = new StringBuilder()
    .append(MYSQLDUMP_CMD).append(' ')
    .append("-u").append(USER_DEFAULT).append(' ')
    .append("-p").append(PW_DEFAULT).append(' ')
    .append(TEST_DB_NAME).append(' ')
    .append(">").append(' ')
    .append(DUMP_LOC)
    .toString();
return new String[] {"/bin/bash", "-c", expr};

If your code to build the command array doesn't wrap spaced arguments in single quotes (or if the JDK doesn't do this for you), then modify the StringBuilder statement to create the wrapped quotes for you.

answered Jul 10, 2013 at 19:34

Toddius Zho

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1 Comment

badperson Over a year ago

was able to resolve this using --result-file option instead of >

user2473015 · Accepted Answer · 2018-11-24 05:04:15Z

Below Code is worked for me

public static void backup() {
        String currentDate = LocalDate.now().format(DateTimeFormatter.ofPattern("yyyy_MM_dd"));
        String backupPath = String.format("%s/%s.%s", Helper.BACKUP_PATH, currentDate, "sql");
        File backupFile = new File(backupPath);
        if (!backupFile.exists()) {
            try {
            backupFile.createNewFile();
            String mysqlCom=String.format("mysqldump -u%s -p%s %s",USER_NAME,PASSWORD,DB);
            String[] command = new String[] { "/bin/bash", "-c",mysqlCom};
            ProcessBuilder processBuilder = new ProcessBuilder(Arrays.asList(command));
            processBuilder.redirectError(Redirect.INHERIT);
            processBuilder.redirectOutput(Redirect.to(backupFile));
            Process process = processBuilder.start();
            process.waitFor();
            LOGGER.info("Backup done");
        } catch (IOException e1) {
            e1.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    } else {
        LOGGER.info("Database already backuped today");
    }
}

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