Invoking the cd utility by itself (that is, without any arguments) will change the current directory to the directory specified by the $HOME environment variable:
nick@nimble ~ $ cd /tmp/ nick@nimble /tmp $ cd nick@nimble ~ $
Invoking the cd utility with a single hyphen (-) argument will return you to the previous directory you were in.
If you accidentally issue a cd without any arguments, typing cd - is a convenient way of returning to the directory you came from—in essence functioning as an undo operation:
nick@nimble ~/a/long/path/to/some/files $ cd nick@nimble ~ $ cd - /home/nick/a/long/path/to/some/files $ nick@nimble ~/a/long/path/to/some/files $
Or, if you want to alternate between two directories, cd - makes this simple:
nick@nimble ~/path/to/some/files $ cd ~/another/path/to/some/files/ nick@nimble ~/another/path/to/some/files $ cd - /home/nick/path/to/some/files nick@nimble ~/path/to/some/files $ cd - /home/nick/another/path/to/some/files nick@nimble ~/another/path/to/some/files $
Garmin is a popular brand of GPS devices. Unfortunately, Garmin makes its MapSource application only for Windows, not Linux. However, Wine runs MapSource, at least for Garmin GPS units that communicate via USB.
The following procedure is based on:
The current Wine package (wine-0.9.56-1.fc8)
A Garmin Vista CX, with the standard USB cable
Install Wine (as root):
# yum install wine
Make sure that you can access the GPS device. For my installation, the device is /dev/ttyUSB0. I found this by examining /var/log/messages when attaching the device. Check the permissions of the device file, and make sure you have access to it, possibly by adding yourself to the group that owns the device. In my case, I had to add myself to the group uucp. Remember to log out and log back in if you add yourself to a new group.
Now, define the device in Wine. This is done as follows (do this using your normal login, not as root):
$ ln -s /dev/ttyUSB0 ~/.wine/dosdevices/com2
This will define the /dev/ttyUSB0 device as COM2 under Wine.
After that, you simply install the software on the Garmin CD. For example, for City Navigator NT (Europe), using your normal login, do the following:
$ cd /media/CNEURNTV9 $ wine ./Setup.exe
At the end, don't opt to start the program directly. Start it afterward via the command line:
$ wine ~/.wine/drive_c/Garmin/MapSource.exe
Using this procedure, I am able to unlock maps, make routes, upload and download from the GPS unit (via USB) and do software updates.
For more information, see my Web page: www.peterverthez.net/gps/garmin-linux.html.
When you are hunting for a configuration problem with services like Apache and MySQL, you may have to execute a sequence of commands repeatedly, such as:
/etc/init.d/apache stop /etc/init.d/mysql stop /etc/init.d/mysql start /etc/init.d/apache start
You can create a script to do this, or you can put all the commands on one line separated by semicolons:
/etc/init.d/apache stop; /etc/init.d/mysql stop; \ /etc/init.d/mysql start; /etc/init.d/apache start
However, as you do other things, you sometimes lose “quick” access to the command line in the shell history. To avoid this, “tag” the line with a comment that will make it easy to find:
/etc/init.d/apache stop; /etc/init.d/mysql stop; \ /etc/init.d/mysql start; /etc/init.d/apache start; #apmy
Now, to recall the command, simply do Ctrl-R + apmy, and you should have the command, as long as you've chosen your “tags” wisely.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Managing Linux Using Puppet
- Non-Linux FOSS: Caffeine!
- Doing for User Space What We Did for Kernel Space
- SuperTuxKart 0.9.2 Released
- Google's SwiftShader Released
- Parsing an RSS News Feed with a Bash Script
- Rogue Wave Software's Zend Server
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide