Installing Fedora Core 10 in text mode
By default, Fedora core 10 will install in graphical mode. This is not ideal for the vast majority of my hosts, since they run inside a VMWare virtual machine. To get Fedora Core 10 to install in text mode, you can hit the key at the install screen and add the keyword "text" to the end of the boot options.
$ read more →Recovering deleted files with ext3grep
While perusing packages on my Debian 5 host, I came across the ext3grep utility. Ext3grep allows you to poke and prod ext file system metadata structures (superblocks, inode bitmaps, block details, etc.), and has the ability to recover deleted files. To see first hand how file recovery works (this is a useful thing to have in your bag of tricks), I first created an ext3 file system to test this out: Once the file system was mounted, I copied over and immediately removed a file: After the file was removed, I used the ext3grep utilities "--dump-name" option to display a list of file names: In the output above, we can see that the services file I previously removed is listed. To recover deleted files, you can run ext3grep with the "--restore-file" option to restore individual files, or with the "--restore-all" option to restore all deleted files: After the restore operation completes, you can change to the RESTORED_FILES directory to view the recovered files: This is pretty fricking sweet, though there are a few caveats I should mention…
$ read more →Disabling SELinux on CentOS Linux hosts
I spend a bunch of time a while back learning how SELinux worked, and it definitely has some useful applications (especially with the tools that were recently added to assist with policy setup). On some of the hosts I support it is overkill, and I disable in one of my kickstart postinstall actions. To disable SELinux, you can change the SELINUX variable to disabled in /etc/selinux/config: If you are performing this action on a running host, you can save a reboot by using the setenforce utility to disable SELinux: If I get some time in the next few weeks, I will clean up my SELinux notes and put them on the main prefetch.net home page.
$ read more →Boot tracing in the Linux 2.6.28 kernel
While perusing the Linux change list, I noticed that boot tracing was introduced in the 2.6.28 kernel: "The purpose of this tracer is to helps developers to optimize boot times: it records the timings of the initcalls. Its aim is to be parsed by the scripts/bootgraph.pl tool to produce graphics about boot inefficiencies, giving a visual representation of the delays during initcalls. Users need to enable CONFIG_BOOT_TRACER, boot with the "initcall_debug" and "printk.time=1" parameters, and run "dmesg | perl scripts/bootgraph.pl > output.svg" to generate the final data." This is pretty sweet, and I will definitely have to test this out once I finish up Redhat cluster suite + GFS testing!
$ read more →Good dpkg and apt-get reference
I have been playing with Debian quite a bit lately, and found Carlo Wood's Debian cheat sheet rather useful. The more I use dpkg and apt-get, the more I wish every operating system had something similar (yum and company don't quite compare). Nice!
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