21 Jan 2009 IP address change notifier script
This is a simple bash script that is run by crontab every 5 minutes on a linux box.
It e-mails me the new address when a change of IP address is detected.
The script (ipchangemail.sh)
#!/bin/bash
# Check if IP-address has changed. If a change has occured, mail me the new address
# Add the following line to crontab if you would like it to be run every 5 minutes:
# */5 * * * * ./ipchangemail.sh
# The network interface I want to monitor
NET_INTERFACE=eth0
# File to keep the latest IP address
IP_FILE=myip.txt
# Mail to this address when a change occur
MAILTO=mail@example.com
# Read the previous IP address from file
source $IP_FILE
CURRENT_IP=`/sbin/ifconfig $NET_INTERFACE | sed -n "/inet addr:.*255.255.25[0-5].[0-9]/{s/.*inet addr://; s/ .*//; p}"`
if [ "$CURRENT_IP" != "$OLD_IP" ]
then
# Send email about address change
`echo "New IP address detected: $CURRENT_IP" | mail -s "New IP address" $MAILTO`
# Write new address to file
`echo "OLD_IP=$CURRENT_IP" > $IP_FILE`
fi
The script can be downloaded here.
Tags: bash, ifconfig, mail, sed
Posted by Hans-Henry Jakobsen
19 Jan 2009 Mount a RAID Reconstructor disk image in linux
This post came to life because I had gotten a image file of a 120GB linux ext2 RAID partition that I couldn’t access using Windows software. The partition had been rescued by RAID Reconstructor, a Windows software that can rebuild RAID arrays by combining the disks from the RAID and store it as one image file.
The solution was to use linux and try to mount it as a loop filesystem. My assumption was that the partition itself had an unknown offset, so I used this script to search and mount the partition. The script tries to mount the partition within the first 20000 blocks. I assume the block size is 512 bytes and I already know that the partition is formatted as ext2.
for ((i=0 ; $i < 20000 ; i=$i + 1)) ; do
mount -t ext2 -o loop,offset=$(($i * 512)) diskimage.img /mnt/point && break
done
If it succeeds you can issue the mount command to get the offset value to the mounted partition
# mount | grep diskimage /dev/loop0 on /mnt/point type ext2 (rw,offset=32256)
In my case the offset was 32256.
This script can also be used to mount a partition from a backup of your filesystem.
Example
This is my example disk I'm going to create an image of
# fdisk -l Disk /dev/hda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/hda1 * 1 14 112423+ 83 Linux /dev/hda2 15 96 658665 83 Linux /dev/hda3 97 3394 26491185 83 Linux /dev/hda4 3395 9729 50885887+ f W95 Ext'd (LBA) /dev/hda5 3395 7218 30716248+ 83 Linux /dev/hda6 7219 8750 12305758+ 83 Linux /dev/hda7 8751 9533 6289416 83 Linux /dev/hda8 9534 9729 1574338+ 83 Linux
Create a backup image of your entire disk
# dd if=/dev/hda of=imagefile.img
To mount one of these partitions as a loop filesystem you can issue a mount command and tell it the right offset. Use the script above if you don't know the offset, it will take the guesswork for you and mount the partition.
Example of mounting /dev/hda3 if the offset is known
# mount -t ext3 -o loop,offset=49664 /dev/hda3 /mnt/point
Determining the offset is easy when you know the disk geometry have access to the file table.
In this case the hda3 partition has an offset of 512 bytes * 96 blocks = 49664.
EDIT
This post could have been avoided if I had known about the linux tool TestDisk. testDisk is a powerful free data recovery software! It was primarily designed to help recover lost partitions and/or make non-booting disks bootable again when these symptoms are caused by faulty software, certain types of viruses or human error (such as accidentally deleting a Partition Table). It could also be used as a forensic tool.
Tags: dd, mount, offset, RAID Reconstructor
Posted by Hans-Henry Jakobsen
13 Sep 2008 Enable query caching in mysql
Query caching is a way to increase the performance of mysql by caching database queries.
It’s quite easy to do and only requires to edit one file, in Debian it’s called /etc/mysql/my.cnf
Add the following lines in the mysqld section
[mysqld] query-cache-type = 1 query-cache-size = 10M
restart the mysql daemon
# /etc/init.d/mysql restart
Verify that query caching is enabled
# mysql -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 33499 Server version: 5.0.32-Debian_7etch6-log Debian etch distribution Type 'help;' or '\h' for help. Type '\c' to clear the buffer. mysql> SHOW VARIABLES LIKE '%query_cache%'; +------------------------------+----------+ | Variable_name | Value | +------------------------------+----------+ | have_query_cache | YES | | query_cache_limit | 1048576 | | query_cache_min_res_unit | 4096 | | query_cache_size | 10485760 | | query_cache_type | ON | | query_cache_wlock_invalidate | OFF | +------------------------------+----------+ 6 rows in set (0.00 sec)
If you see something like the out above, caching is enabled.
Posted by Hans-Henry Jakobsen
05 Sep 2008 Create a PDF document from man page
man -t passwd | ps2pdf -> passwd.pdf
Tags: ps2pdf
Posted by Hans-Henry Jakobsen
02 Sep 2008 Rename files by wildcard pattern and correct the EXIF timestamp metadata
This is a little script I’ve written to correct all my image files since the EXIF timestamp information is one hour out of sync. The filenames have been renamed to comply to the EXIF information and has to be renamed again because of the one hour scew. The filename can look something like this 20080102-1201_DSC_0910.JPG where the name is built up like YYYYMMDD-HHMM_Original_Filename.JPG
Remember to backup your imagefiles before you continue. You have been warned!
Rename files using wildcard pattern
This is the files we are going to rename
20080102-1201_DSC_0910.JPG 20080105-1923_DSC_1006.JPG 20080111-1220_DSC00189.JPG 20080122-0929_DSC00190.JPG
The mmv command is a command that lets you move/copy/append/link multiple files by wildcard patterns. It can be installed in Debian (or Debian based distributions like Ubuntu) by issuing the command
# aptitude install mmv
Now rename the files back to their original name
# mmv "*_DSC*" "DSC#2"
The result after this operation looks like this
DSC_0910.JPG DSC_1006.JPG DSC_1179.JPG DSC_1302.JPG DSC_1587.JPG
Correct the EXIF timestamp using exiv2
Next adjust the EXIF information stored in the image files to fix the one hour difference. This can be done using different EXIF tools like exiftool, but I will show you how it can be done using jhead and exiv2. The advantage with exiv2 is that it can also handle Nikon NEF files while jhead only can prosess JPG.
The current timestamp can be determined as follows
# exiftool DSC_0910.JPG | grep "File Mo"
The result in this case is
File Modification Date/Time : 2008:01:02 08:34:09
Adjust EXIF time info one hour forward using exiftool
# exiftool -AllDates+=1 DSC_0910.JPG
Other tools that could have done the job
Adjust EXIF time info one hour forward using jhead
# jhead -ta +1 DSC_0910.JPG
Install the jhead package using aptitude as mentioned earlier for the mmv package
Adjust EXIF time info one hour forward using exiv2
# exiv2 ad -a 1 DSC_0910.JPG
Rename files back to YYYYMMDD-HHMM_Original_Filename.JPG
It is now time to rename the files back to the YYYYMMDD-HHMM_Original_Filename.JPG format I used before this operation. This operation has been describe in a previous post named Rename image files according to EXIF date
exiv2 -r'%Y%m%d-%H%M_:basename:' rename $(ls D*)
The script
#!/bin/bash -x # Needed software: # exiftool # exiv2 # mmv # Script tested on Nikon D80 and Sony Cybershot DSC-W12 files # Make a printout of how the files look like now ls -l > repair_name_and_exif_before.txt # Rename files to remove date formatting back to original name mmv "*_DSC*" "DSC#2" # Change EXIF info on JPG files (order is important) exiftool -overwrite_original -AllDates+=1 D*.JPG # Preserve date/time of original file when writing exiftool -overwrite_original '-DateTimeOriginal>FileModifyDate' D*.JPG # Change EXIF info on NEF files (order is important) exiftool -overwrite_original -AllDates+=1 '-DateTimeOriginal>FileModifyDate' D*.NEF # Preserve date/time of original file when writing exiftool -overwrite_original '-DateTimeOriginal>FileModifyDate' D*.NEF # Rename files back to date formatting (YYYYMMDD-HHMM_Filename) based on the new EXIF info exiv2 -r'%Y%m%d-%H%M_:basename:' rename $(ls D*) # Make a printout of how the files look like after conversion ls -l > repair_name_and_exif_after.txt
Tags: Debian, EXIF, exiv2, jhead, JPG, mmv, NEF, Nikon, rename, Sony
Posted by Hans-Henry Jakobsen
