Finding out tablespace size, used space and free space in Oracle database

This query which should be run as SYS or SYSTEM user, will give you the following information:

• Tablespace Name
• % used
• Space allocated to tablespace
• Space used in tablespace
• Space free in tablespace
• Number of datafiles used by tablespace

SELECT  a.tablespace_name,

    ROUND (((c.BYTES - NVL (b.BYTES, 0)) / c.BYTES) * 100,2) percentage_used,

    c.BYTES / 1024 / 1024 space_allocated,

    ROUND (c.BYTES / 1024 / 1024 - NVL (b.BYTES, 0) / 1024 / 1024,2) space_used,

    ROUND (NVL (b.BYTES, 0) / 1024 / 1024, 2) space_free, 

    c.DATAFILES

  FROM dba_tablespaces a,

       (    SELECT   tablespace_name, 

                  SUM (BYTES) BYTES

           FROM   dba_free_space

       GROUP BY   tablespace_name

       ) b,

      (    SELECT   COUNT (1) DATAFILES, 

                  SUM (BYTES) BYTES, 

                  tablespace_name

           FROM   dba_data_files

       GROUP BY   tablespace_name

    ) c

  WHERE b.tablespace_name(+) = a.tablespace_name 

    AND c.tablespace_name(+) = a.tablespace_name

ORDER BY NVL (((c.BYTES - NVL (b.BYTES, 0)) / c.BYTES), 0) DESC;

How to fix Cannot open your terminal '/dev/pts/#' - please check.

simply run :

script /dev/null

and try again.

How to find out which jar file a class is loaded from

There are ways to programmatically find out where the java classloader loads a certain class from. But what if you don't have access to the source code and are on a production environment.
In these cases JVM provides you with a nice option :

-verbose:class

So if you are working with a an app server like WebLogic or Tomcat, just modify the appropriate script that sets JVM arguments and you should be able to see output like this in your server log :

 [Loaded java.io.Serializable from C:\Program Files\Java\jdk1.7.0_04\jre\lib\rt.jar]
[Loaded java.lang.Comparable from C:\Program Files\Java\jdk1.7.0_04\jre\lib\rt.jar]
[Loaded java.lang.CharSequence from C:\Program Files\Java\jdk1.7.0_04\jre\lib\rt.jar]
..............................................................................
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Best way to transfer large file or resume dropped ftp/scp file transfers

When transferring large files your first choice should be rsync, since it gives you the ability to resume unfinished/dropped transfers. However, if you started a large file transfer with ftp/sftp or scp and the connection was lost during the transfer, you don't need to start over again. Simply run rsync the following way and it will resume your transfer :

rsync --partial --progress --rsh=ssh <USER>@<HOST>:<REMOTE_FILE_PATH> <LOCAL_FILE_PATH> 

This command is what should be used for large file transfers.

How to create an executable jar with 3rd party dependencies included in the jar

If you have written a small java utility that has dependencies on other 3rd party jar and you would like other people to use it without building your jar, you will need to include those jars in your jar. To do this you need to use the maven-assembly-plugin .

So inside <build> ... <plugins>  of your pom.xml put

<plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>your.fully.qualified.MainClass</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
</plugin>

Then run maven using :  mvn clean compile assembly:single