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Remove old kernels (*-generic and *-generic-pae) via apt-get on debian/ubuntu based systems. Tested on ubuntu 10.04 - 12.04.
Use this the next time you need to come up with a reasonably random bitstring, like for a WPA/WPA2 PSK or something. Takes a continuous stream of bytes coming from /dev/urandom, runs it through od(1), picking a random field ($0 and $1 excluded) from a random line and then prints it.
This command sets the volume for the main PulseAudio "sink" (usually the ALSA output interface) to the maximum, 100% (the 0x10000 in the command). To set it to an arbitrary volume, replace 10000 with the volume you want times 100 (so 75% becomes 7500).
This returns the hardware serial number. Dell calls this the "Service Tag" and it can be used to retrieve warranty information or used for RMA / repairs.
Lots of fun to run on nfs clients when the server or network connection is having issues
Disabling an interface's multicast filter is like disabling IGMP snooping on a switch. It is useful for testing and troubleshooting.
Daemontools won't always properly reap it's children. Sometimes when you need to kill the main svscan process, you want to also clean up all of it's children. The way to do that is to send a signal to the entire process group. It is a bit tricky
Sometimes you want to see all of the systcls for a given $thing. I happened to need to easily look at all of the vm sysctls between two boxes and compare them. This is what I came up with.
See the summary.
To get most of you HDD/SSD driver you need to make sure you partition are aligned, if not the speed penalty can be up to 50% slower!
this simple one liner will check to see if each partition start sector is divided by 512
you need to change sda with your driver
if you find the one of your partitions is not aligned use gparted to move the start sector of the partition to be divided of 512
"What it actually shows is going to be dependent on the commands you've previously entered.
When you do this, bash looks for the last command that you entered that contains the substring "ls", in my case that was "lsof ...". If the command that bash finds is what you're looking for, just hit Enter to execute it. You can also edit the command to suit your current needs before executing it (use the left and right arrow keys to move through it).
If you're looking for a different command, hit Ctrl+R again to find a matching command further back in the command history. You can also continue to type a longer substring to refine the search, since searching is incremental.
Note that the substring you enter is searched for throughout the command, not just at the beginning of the command." - http://www.linuxjournal.com/content/using-bash-history-more-efficiently
When I do a major change in my entities, I want to find a way to find all my Entities names and create the commande for me.
So instead of doing ls src/Your/OwnBundle... and then do it manually, this helps a lot.
Creates a single primary partition starting at sector 0 and extending to the end of the disk. Use with care.
this work even if a partition table exist
small update for this command to work with linux kernels 3.x
This command displays the CPU idle + used time using stats from /proc/stat.
If you changed the default policy on any chain other than filter table chain's, this won't be enough.
Shows all configurations to apt and dpkg, rarely changed, you probably still have the default configuration. Go ahead and explore your configuration if you dare, perhaps change your apt-cache directory, Dir::Cache "var/cache/apt/"; or the names of the log files.