So I was trying to do some work the other morning in my hotel room and my Windows 7 computer gave me the dreaded blue screen of death and would not boot past loading a certain library file. I was able to boot into an Ubuntu disk that I happened to have and found that there were many S.M.A.R.T. errors on the disk and wished I had thought to monitor this. So it seemed that my drive was cooked and I could not get any of the data from it.

    I was disappointed that Spinrite was unable to save me from the problems that I was having and I paid 90 bucks for it. So I turned to tools in Linux that might do the job. I had used the dd utility to copy the contents of my drive to a new drive in the past, but dd will exit on the first error. So I found that there is an addition to the dd program called ddrescue which is part of the GNU Project.

This utility will let you copy the contents of a disk or partition and allow you to skip the errors or even retry the error spots a number of times.

The command line is something like:

    ddrescue -r 3 /dev/sda1 /media/newvolume/diskimage.iso /media/newvolume/logfilefordiskimage

The really nice thing is if you have to stop the command for some reason, it will restart from the end of the log file. It does take quite a bit of time. I am 6 1/2 hours into recovering a 500GB disk, but it beats losing all my data. I will follow up this post with the results of the rescue and the next steps I took to recover the data.

Part 2 of article

Tags: dd, ddrescue, Linux

Sometimes you have a drive that your want to mount under Linux. The mount command can make the drive available to you. But you need to also create a directory to hold the mount point.

mkdir /mnt/drivepoint

Then you can mount the drive to that mount point by using the mount command and giving the device identifier, in this case it is /dev/sda1, and the mount point which we created as /mnt/drivepoint. One thing to note, is that the mount will use whatever directory you specify, so if there are files located in the directory you use as a mount point, they will no longer be visible.

mount /dev/sda1 /mnt/drivepoint

This must be run as root or with the sudo command.

Tags: Linux, OS, Utilities

Every once in awhile, I need to backup a large directory from another computer. This can be done by creating a zip or tar of the files you are looking to save and then copying those zips to the other computer. But what it you have a very large directory and not enough room to store the extra file. Here is a way to use tar over ssh:

ssh tar zcvf – /wwwdata | ssh root@backupserver.mydomain.com “cat > /backup/wwwdata.tar.gz”

Did you know? You can Set file timestamp using touch command. One way to do this is:
touch -c -t YYMMDDhhmm filename.txt

I had to write a backup script the other day and used the find command to find the files that were older than a given amount of days.

DAYS_TO_KEEP=7
find /path/to/files* -type f -name *.bak -mtime $DAYS_TO_KEEP -exec rm {} ;

The -name argument uses the escaped asterisk so command completion does not replace it with all the file names.

The -mtime argument takes a number that is the number of days to look at.

The -exec argument takes a command and the {} is replaced with the current file name and the ; is the end of the command.

This is a small part of the power of the find command.

If you don’t have access to a Unix environment on your windows box, you can still search files with findstr. The findstr command will allow you to search files close to the same way as grep.

findstr /S "search string"

will recursively find your string in the current directory and subdirectories.

There are more options that you can find if you run the following command:

findstr /?

will show you the help message.

Tags: Utilities, Windows

So every once in a while I want to see the progress of an upload or backup. So I turn to the watch command in Linux. The watch command gives the user the ability to re-run a command and see the updated output.

The syntax is ‘watch -n -d .

So for watching a file downloads progress you could run the following:

watch -n 30 ls -l filedownloading

This would show the ls output and you could watch the size of the file grow as it is dowload progress.

When attempting to run ant I get the following message: “Unable to locate tools.jar. Expected to find it in C:Program Files (x86)Javajre6libtools.jar”

This had to do with my JAVA_HOME not pointing to a Java JDK.

So if you download a JDK and update your JAVA_HOME environment variable to point to that directory, ant should run happily.

In BASH:
export JAVA_HOME=/path/to/jdk

IN DOS:
set JAVA_HOME=c:PATHtojdk

Tags: ant, Java

Every once in awhile I go back and try to figure out how to create a basic ant build.xml file. So I am just placing a sample build.xml here.

The directory structure should be something like
./build.xml
./src/HelloWorld.java

The targets will create the build directory and compile the source and run a test execution of the class.

<project name="HelloWorld" basedir="." default="main">
<target name="clean">
<delete dir="build"/>
</target>

<target name="compile">
<mkdir dir="build/classes"/>
<javac srcdir="src" destdir="build/classes"/>
</target>

<target name="jar" depends="compile">
<mkdir dir="build/jar"/>
<jar destfile="build/jar/HelloWorld.jar" basedir="build/classes">
<manifest>
<attribute name="Main-Class" value="HelloWorld"/>
</manifest>
</jar>
</target>

<target name="run" depends="jar">
<java jar="build/jar/HelloWorld.jar" fork="true" />
</target>

<target name="main" depends="clean,run"/>

</project>

Tags: ant

This turns off word wrap in the vi window

:set nowrap

to enable it again:

:set wrap

Tags: editors, vi