I use a simple bash script /usr/local/bin/move-cam-files.sh to let exiftool move photos and videos from our camera to directories on our file server, based on creation date as per media file metadata:
#! /bin/bash -x
move() {
exiftool -r -v -ext $2 '-directory<DateTimeOriginal' \
-d "/home/storage/$3/%Y/%m" "$1"
}
# directory where to read media files from is $1
# if unspecified use current directory
dir=${1:-.}
move $dir AVI videos
move $dir JPG photos
Sometimes you work on Windows as a restricted user, without admin rights. Like many other good software packages, Cygwin can be installed anyway (see the respective FAQ entry).
These are the steps I used:
--no-admin” option#! /bin/sh rm setup-x86_64.exe wget http://cygwin.com/setup-x86_64.exe chmod u+x setup-x86_64.exe run ./setup-x86_64.exe --no-admin
chmod ugo+x /usr/local/bin/cygwin-setup.sh
mintty.exe -i /Cygwin-Terminal.ico -
with
mintty.exe -i /Cygwin-Terminal.ico /bin/bash -l -c 'cygwin-setup.sh'
Whenever you want to run the Cygwin installer to install or remove packages, you can just execute the shortcut or run cygwin-setup.sh from the Cygwin command prompt.
Alternatively, you could also use the pure command-line tool apt-cyg.
Please note: The following instructions are for ssh logins on a remote host. The approach is not suitable for executing remote commands via ssh.
When you work on a remote Linux or Unix server (via ssh) you sometimes cannot control your login shell and/or its default config file. For example, you might be sharing the same user account on the server with other people or the use of the chsh tool might be locked down.
Maybe the default shell is something like ksh, or if bash is used maybe the .bashrc sets vi key bindings. This can be annoying if you are used to standard Linux bash with its default Emacs style bindings.
In these cases you can do the following, assuming bash is installed and in the path on the host:
1) Create /usr/local/bin/sbash.sh (on Windows, use Cygwin).:
#! /bin/bash
set -x
if [ "$#" -gt 0 ]; then
user_at_host="$1"
shift
ssh_options="$@"
else
set +x
echo Usage: $(basename "$0") user@host [ssh-options]
exit 1
fi
ssh -t $ssh_options \
$user_at_host \
"bash --rcfile .bashrc.for-remote-user-${USER}"
Make the file executable using something like chmod ugo+x /usr/local/bin/sbash.sh. You can then use it for remote logins like the ssh command, for example:
oliver@basement:~$ sbash.sh user@host
The $USER variable in the sbash.sh script will be substituted by the local shell with your local user name, which in this example is “oliver”.
2) On the host create ~/.bashrc.for_remote_user_USERNAME where USERNAME is the user name from the ssh client as mentioned above:
user@host$ vim $HOME/.bashrc.for-remote-user-oliver
Make sure this file name matches the –rcfile option in your ssh command.
You can then edit and use this file like a normal .bashrc file, i.e. for setting your favorite environment variables, bash options, aliases, etc.
I have upgraded my minimal Debian VM to current Debian stable (“wheezy”). It comes in OVA format which is deployable to Virtualbox or VMware.
The Debian system JDK, i.e. the location of java, javac, etc. commands in the PATH, is still OpenJDK 6 because that is the default-jdk on wheezy and the Jenkins deb packages from jenkins-ci.org depend on it. In particular this means that the Tomcat / Jenkins process itself is executed by OpenJDK 6.
But my Jenkins installer now also installs OpenJDK 7 and pre-configures it as the default JDK for Jenkins jobs. That means you can now use this Jenkins instance to build your Java 7 projects, as well as older Java projects.
Please follow the step-by-step installation instructions if you want to use the VM. It consists completely of Free / Open Source software. I provide it for download “as is” without any warranty of any kind.
This blog post describes how I manage my many website logins (usernames, passwords). I am very interested in how I can improve my current approach. I want it to be highly secure and highly convenient. Please feel free to add your comments and suggestions!
I try to use secure passwords for all of my web accounts, i.e. long random combinations of “special characters”, mixed case letters and numbers. They are usually so secure that I definitely cannot remember them.
So I let my web browser remember, manage and auto-fill my website logins. I use
The approach works well and I never have to memorize my passwords. But my worries are:
Sometimes you might want to include Java collections content in a log message. But standard Java collections do not provide a useful toString() implementation. So developers often use a helper method like this:
/**
* @param collection A collection
* @return A string listing all collection items
*/
public static String toContentString(Collection<?> collection) {
return Arrays.toString(collection.toArray());
}
Then in typical slf4j log output code you might have something like this:
log.debug("Processing list: {}", toContentString(list));
But if list is long, then this code will cause unnecessary overhead in your application whenever it runs at a log level that does not actually log debug messages.
A simple solution for this is to use a wrapper object instead:
log.debug("Processing list: {}", toStringWrapper(list));
A simple toStringWrapper(..) implementation could be this:
/**
* Provides a wrapper object that can be used for logging of
* collection content
*
* @param collection A collection
* @return A wrapper toString() implementation listing all
* collection items
*/
public static Object toStringWrapper(Collection<?> collection) {
return new Object() {
@Override
public String toString() {
return toContentString(collection);
}
};
}
This postpones the String generation until slf4j actually calls toString() on the log message parameter to substitute it for the ‘{}’ placeholder. And this substitution only happens if the log level actually requires it, i.e. less cpu cycles wasted on unused log message parameters.
Things I like about some companies’ approach to software installation on employee’s machines:
This leaves room for a focus on education, knowledge sharing and trust that employees act responsibly.
Based on my experience, these are some useful policies / objectives for Open Source use at the workplace (especially for IT companies):
I use a small headless Debian system as file server for all family photos, videos, documents, etc. Its hostname is “bubba”. I have recently set it up to run backups to an external harddrive, using cron and rsync.
The external disk is a 500G laptop SATA disk in an USB/eSATA enclosure. It requires no separate power supply. So far I have only got it to work over USB. Somehow the eSATA does not work for me on Debian 6 (aka “squeeze”), even though the file server has an eSATA port.
sudo mkdir /mnt/backup
sudo apt-get install ntfs-3g
I use NTFS as the filesystem on the backup disk because we wanted it to be compatible with MS Windows. The Debian Linux on the file server uses ntfs-3g for mounting the disk read-write. Unfortunately that only works well with root rights, so I configured sudo to permit myself password-less mounting and unmounting of the device.
oliver ALL = NOPASSWD: /bin/mount /mnt/backup, \
/bin/umount /mnt/backup
The nightly backup process itself is a simple non-destructive local rsync command, wrapped by mount and unmount commands, to make sure that we can unplug the external disk anytime we want (just not around midnight).
oliver@bubba:~$ crontab -l
0 0 * * * /home/oliver/shared/scripts/backup.sh
#! /bin/sh
if mountpoint /mnt/backup; then
sudo umount /mnt/backup
fi
sudo mount /mnt/backup
if [ $? -eq 0 ]; then
rsync -avvih --progress \
--exclude /downloads \
--exclude /movies \
/home/storage/ /home/oliver/backup \
> /tmp/cron_output.log 2>&1
fi
sudo umount /mnt/backup
Symlink in my home for convenience:
oliver@bubba:~$ ls -l /home/oliver/backup
lrwxrwxrwx 1 oliver users 11 Aug 7 21:38 /home/oliver/backup -> /mnt/backup/
Entry in /etc/fstab:
oliver@bubba:~$ grep "/mnt/backup" /etc/fstab
/usr/local/share/backup /mnt/backup ntfs-3g defaults 0 0
Device symlink /usr/local/share/backup:
oliver@bubba:~$ ls -l /usr/local/share/backup
lrwxrwxrwx 1 root staff 84 Jun 23 01:51 /usr/local/share/backup -> /dev/disk/by-id/usb-WDC_WD50_00BPVT-00HXZT3_FDC0FD500000000FD0FF61A6103926-0:0-part1
/home/oliver/shared/scripts/backup.sh &
less /tmp/cron_output.log
The symlink to the device file is the ugliest part of the whole solution. Currently I have to plug the disk directly into a USB slot on the file server because if I connect it via a USB hub, it will appear under a different name in /dev/disk/by-id and my symlink won’t work. I would like to use a udev rule instead that automatically creates an identical symlink no matter how the the disk is plugged in.
I would also like to implement a 2-way backup so that files we put on the external disk, for example photos from a trip to relatives, will be mirrored to the file server. It should be just another rsync command going in the opposite reaction.
Maybe I would also like the backup process to start right away when the disk is plugged in, in addition to the nightly cron job. This would probably require another udev rule.
The site explainshell.com provides explanations for concrete Linux shell commands, specifically for the options used.
java.net.useSystemProxies=true
Oleander Donovan's IT blog 