VBS Script for Outlook Email Message

Simple tip, this Visual Basic (VBS) script is used to open a new Outlook email message and automatically populate to: and subject:.

' Sleep for 3 minutes
WScript.Sleep(1000 * 60 * 30)
Set oolApp = CreateObject("Outlook.Application")
Set email = oolApp.CreateItem(0)
email.Recipients.Add("user@somedomain.org")
email.Subject = "Subject for email"
email.Display()

Enjoy!

My TAR incremental backup strategy

Quick tip:

Here is my TAR incremental backup strategy.  I have been using rsync for a long time but recently ran into a number of permission and symlink issues rsync’ing from an Ubuntu guest to a Windows host.

A few comments on the bash script below:

1.    The do_backup() function is a common function and it does all the work of the backup.

2.    The do_backup() function has to take 4 parameters

a.    $1 is the source directory.  This is the directory you want to backup, OR, this is the directory that has stuff in it you want to backup.

b.    $2 is the destination directory.  This directory is relative to ${backupHome}, but still starts with the / character.  This is where you want the TAR balls to end up.

c.    $3 is a name for the backup.  This is used to create the names of the TAR balls and the SNAR indexes.

d.    $4 is a command to run inside the source directory ($1) which will be piped to the `tar` command for backup.

3.    This strategy makes a full backup (level 0) and a single incremental backup (level 1).  The level 1 backup is (correctly) overwritten each time a backup is performed.

4.    A full backup is performed if:

a.    A backup has never been done before

b.    The size of the incremental backup is greater than 10% of the size of the full backup.

Bash script

#!/bin/bash

backupHome=/mnt/hgfs/Backup

#

# First check to see that that backup directory exists.

# If it does, continue. Otherwise, exit with error code.

#

if [ ! -d "${backupHome}" ]; then

        echo "Directory ${backupHome} does NOT exist, exit."

        exit 1;

else

        echo "Directory ${backupHome} exists, continue."

fi

# do_backup "/etc/postfix" "/etc/postfix" "main" 'echo main.cf'

function do_backup {

    local backupSrc=$1

    local backupDst=${backupHome}${2}

    local backupNme=$3

    local backupDir=$4

    local fullSnarFile=${backupDst}/${backupNme}_full.snar

   local fullTarFile=${backupDst}/${backupNme}_full.tar.gz

    local level1SnarFile=${backupDst}/${backupNme}_level_01.snar

    local level1TarFile=${backupDst}/${backupNme}_level_01.tar.gz

    echo "Backup: ${backupNme} from: ${backupSrc} to: ${backupDst}"

    mkdir -p ${backupDst}

    cd ${backupSrc}

    # Check file percentages and see if full backup is needed

    if [ -f ${fullTarFile} ] && [ -f ${level1TarFile} ]

    then

        local fullSize=$(stat -c%s ${fullTarFile})

        echo "  Size of ${fullTarFile} is ${fullSize}"

        local level1Size=$(stat -c%s ${level1TarFile})

        echo "  Size of ${level1TarFile} is ${level1Size}"

        local percentChange=$(echo "scale=2; (${level1Size}/${fullSize}) * 100" | bc)

        percentChange=$(printf "%.0f" ${percentChange})

        echo "  Percent change is ${percentChange}"

        if [ ${percentChange} -gt 10 ]

        then

            echo "  Prepare for a new full backup"

            rm -f ${fullSnarFile}

            rm -f ${level1SnarFile}

            rm -f ${level1TarFile}

        fi

    fi

    # If file does not exist, perform full backup

    if [ ! -f ${fullSnarFile} ]

    then

        echo "  Performing full backup"

        eval ${backupDir} | tar --listed-incremental ${fullSnarFile} -cpzf ${fullTarFile} -T -

    else

        echo "  Performing level 1 backup"

        cp -f ${fullSnarFile} ${level1SnarFile}

        eval ${backupDir} | tar --listed-incremental ${level1SnarFile} -cpzf ${level1TarFile} -T -

    fi

}

Examples

Let’s take a look at a few usage examples.  For these examples, assume that ${backupHome} is /mnt/hgfs/Backup/ like in the script.

Example 1:

do_backup "/home/apache" "/home/apache" "apache" 'echo .'

Example 1 means you want to backup the /home/apache directory to the /mnt/hgfs/Backup/home/apache directory. The parameter “apache” means the following files will be created:

/mnt/hgfs/Backup/home/apache/apache_full.snar

/mnt/hgfs/Backup/home/apache/apache_full.tar.gz

/mnt/hgfs/Backup/home/apache/apache_level_01.snar

/mnt/hgfs/Backup/home/apache/apache_level_01.tar.gz

Finally, ‘echo .’ means the TAR ball will contain everything inside the /home/apache directory

Example 2:

do_backup "/etc/postfix" "/etc/postfix" "main" 'echo main.cf'

Example 2 means you want to backup the /etc/postfix directory to the /mnt/hgfs/Backup/etc/postfix directory. The parameter “main” means the following files will be created:

/mnt/hgfs/Backup/etc/postfix/main_full.snar

/mnt/hgfs/Backup/etc/postfix/main_full.tar.gz

/mnt/hgfs/Backup/etc/postfix/main_level_01.snar

/mnt/hgfs/Backup/etc/postfix/main_level_01.tar.gz

Finally, ‘echo main.cf’ means the TAR ball will ONLY contain the /etc/postfix/main.cf file!

Example 3:

do_backup "/home/michael" "/home/michael" "michael" 'find . -type f -name ".forward" -o -type d -name "cron" -o

-type d -name "Applications" -o -type d -name ".ssh"'

Example 3 means you want to backup the /home/michael directory to the /mnt/hgfs/Backup/home/michael directory. The parameter “michael” means the following files will be created:

/mnt/hgfs/Backup/home/michael/michael_full.snar

/mnt/hgfs/Backup/home/michael/michael_full.tar.gz

/mnt/hgfs/Backup/home/michael/michael_level_01.snar

/mnt/hgfs/Backup/home/michael/michael_level_01.tar.gz

Finally, 'find . -type f -name ".forward" -o -type d -name "cron" –o -type d -name "Applications" -o -type d -name ".ssh"' means the TAR ball will ONLY contain the following:

/home/michael/.forward

/home/michael/cron/

/home/michael/Applications/

/home/michael/.ssh/

Enjoy!

References

Whipp, Paul. (2010, December). Using tar for full and incremental backups. paulwhippconsulting.com. Retrieved April 4, 2016, from http://paulwhippconsulting.com/blog/using-tar-for-full-and-incremental-backups/

Reading MANIFEST.MF Values From a JAR File on your Class Path

Abstract
Recently, I was looking at building a simple "about" page for my newest application (See project Riviera, a database versioning source code management tool).  I started to build a properties file Maven would filter values into, but then I realized it was not necessary.  The JAR MANIFEST.MF file had almost all the metadata already.  So all I had to do was read the properties from MANIFEST.MF, which I found more difficult than I thought it should be. Here's my solution.

Code
Listing 1 shows the code.

Listing 1: Code to read MANIFEST.MF from JAR file on the class path

Attributes attributes;
try {
    URL jarURL 
        = this.getClass().getProtectionDomain().getCodeSource().getLocation();
    
    URI manifestUri 
        = new URI(String.format("jar:%s!/%s", jarURL, JarFile.MANIFEST_NAME));
    
    InputStream is 
        = manifestUri.toURL().openStream()
    
    Manifest manifest 
        = new Manifest(is);
    
    attributes 
        = manifest.getMainAttributes();            

    is.close();
} catch (Exception e) {
    attributes = new Attributes();
}

Let's take a look at this code in a bit more detail.

The URI object is the key to being able to read the MANIFEST.MF file from a JAR.  To read the contents of a JAR file, a properly formatted URI string looks like this:

"jar:file:/C:/path/to/file.jar!/META-INF/MANIFEST.MF"

The jar:file and ! parts are required in the URI.  The rest of the URI depends on the specific location of the JAR file on your file system and what file in the JAR you want to stream.  Knowing what file you want to read is a given, but how do you get the fully-qualified location of the JAR file?

It stands to reason that if the JVM is executing code from a class it got from a JAR file then the JVM should be able to tell you where that JAR file is located. After all, the JVM needs to know where the JAR file is in order to load the class!  Turns out its simple to find this information.  You get the fully-qualified location of the JAR file from a class's ProtectionDomain that comes from the JAR file.  Once you have the fully-qualified location, you can build a properly formatted URI string.  Then once you have a URI object, then the magic happens.

From the URI object you can get a URL object by using URI#toUrl().  Then after you have a URL object you get an InputStream to the resource using the URL#openStream() method. Under the covers, the URL object determines it needs a JarURLConnection to open the stream.

Once you have the InputStream, pass it along to the Manifest constructor and you're done!  Use Manifest#getMainAttributes() to get the Attributes and then use Attributes#getValue(key) to get the value you want.

Let's it!  Now you can read the the name/value attributes from the MANIFEST.MF file.

Enjoy!

References
Bozho. (2010, February 16). How to read a file from a jar file?. stackoverflow.com. Retrieved January 27, 2016 from http://stackoverflow.com/questions/2271926/how-to-read-a-file-from-a-jar-file.