Category: Shell
Simple Disk Benchmarking in Linux Using ‘dd’
A great way to do a real-world disk test on your linux system is with a program called dd. dd stands for data description and is used for copying data sources. A simple command to do real-world disk write test in linux is: 1dd bs=1M count=512 if=/dev/zero of=test conv=fdatasync This creates a file named ‘test’ [...]
What a Resilver Looks Like in ZFS (and a Bug and/or Feature)
At home I have an (admittedly small) ZFS array set up to experiment with this neat newish raid technology. I think it has been around long enough that it can be used in production, but I’m still getting used to the little bugs/features, and here is one that I just found.
After figuring out that I had 2 out of 3 of my 1TB Seagate Barracuda hard drives fail, I had to give the array up for a loss and test out my backup strategy. Fortunately it worked and there was no data loss. After receiving the replacement drives in from RMA, I rebuilt the ZFS array (using raidz again) and went along my merry way. After 6 months or so, I started getting some funky results from my other drive. Thinking it might have some issue as with the others, I removed the drive and ran Seatools on it (by the way, Seatools doesn’t offer a 64-bit Windows version – what year is this?).
The drive didn’t show any signs of failure, so I decided to wipe it and add it back into the array to see what happens. That, of course, is easier said than done.
Disabling The hald-addon-storage Service On CentOS/RedHat
The hald – Hardware Access Layer Daemon – runs several processes in order to keep track of what hardware is installed on your system. This includes polling USB Drives and ‘hot-swap’ devices to check for changes along with a host of other tasks. You might see it running on your system as follows: 12342474 ? [...]
Adding Random Quotes to the Bash Login Screen
According to “official” system administrator rules and guidelines you shouldn’t be adding so-called vain scripts to the login prompt – only utilities that will add something useful to the system (for example, current system load, memory and disk usage, etc). However I have some systems that I frequently connect to and thought it would be [...]
Another Bash One Liner To Delete Old Directories
We received a tip from blog readers Christian and Michael for alternatives to the command to delete all directories older than a certain period of time. These both work in bash and can be used in scripts to clean up old backup directories or any situation where you need to delete old directories from the [...]
One Line Linux Command to Print Out Directory Tree Listing
My professor sent us this little one liner (ok, I had to format it to 2 lines to fit in this blog. You know what I mean) which prints out the current directory tree: ls -R | grep “:$” | sed -e ‘s/:$//’ -e ‘s/[^-][^\/]*\//–/g’ \ -e ‘s/^/ /’ -e ‘s/-/|/’ What’s going on here?
One Line Batch Rename Files Using CSV Input File and awk
The Bash command environment, which is the namesake of this blog, is very flexible in that it allows you to manipulate the filesystem in many ways. Awk and sed are very powerful tools that allow you to do this rename with a simple one line command. This post will walk you through doing this with [...]
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