If you look in ps for a process, you will usually see the characters S or R… and sometimes others. But what do they mean?
The kernel contains something called a run queue. When a process is ready to run, it tells the kernel that it needs some cycles from the CPU. Once [...]
Signals are one of the most visible aspects of the Linux operating system. They are also one of the least understood. Every sysadmin, even the PFYs who aren’t PFed yet, know how to kill a process. But do you know how this works underneath? Do you know how flexible the linux [...]
I’m getting lot of posts in tonight so that I won’t feel so bad when I wait till the weekend to write more. :-) Besides, this topic is important enough that I just want to get it out there.
Strace is one of the single most important troubleshooting tools you will ever use. [...]
Linux has many different kinds of files. First let’s start with a little more basic discussion: what is a file?
Basically, a file is anything that can have a file descriptor associated with it.
What is a file descriptor?
Ahh. Glad you asked. Sit down, this could take a bit.
Linux is POSIX compliant, which [...]
Sometimes when on a Linux system, you will encounter a problem with running out of disk space when it appears that you haven’t. This is because there are actually two different resources on a Linux filesystem.
Disk space – this is the total amount of space allotted to all of your files.
Inodes – this is [...]
This is one of those topics that separates the men from the boys, so to speak. Backups. Always, always, always have them.
Do not treat RAID arrays as if they are inviolable. It’s always a possibility that more than one disk could fail. And it’s also a possibility that the hardware itself [...]
Today I’ll be covering a critically important part of Linux that gets no airtime at all, and that’s the shared memory subsystem. The closest you’ll come to it in most cases is seeing a /dev/shm filesystem when you type df. That is a recent development, however.
The shared memory subsystem came about because of [...]
OK, this first trick involves getting your root password back when you’ve lost it. Ever had that happen? It can be rather nerve-wracking. And if you try to reboot the box and bring it up into single-user, it may actually ask for your password before allowing you to get a shell. [...]