Linux Memory Management – Understanding a Program in Memory

Posted on in Categories Howto, Linux last updated January 27, 2009

Excellent article! It explains how programs are laid out in memory.

From the blog post:

Memory management is the heart of operating systems; it is crucial for both programming and system administration. In the next few posts I’ll cover memory with an eye towards practical aspects, but without shying away from internals. While the concepts are generic, examples are mostly from Linux and Windows on 32-bit x86. This first post describes how programs are laid out in memory. Each process in a multi-tasking OS runs in its own memory sandbox. This sandbox is the virtual address space, which in 32-bit mode is always a 4GB block of memory addresses.

=> Anatomy of a Program in Memory

FreeBSD 7.2RC Released

Posted on in Categories FreeBSD, Hardware, Howto, Networking, News last updated April 25, 2009

The second of two planned Release Candidates for the FreeBSD 7.2-RELEASE cycle is now available. ISO images for Tier-1 architectures are now available on most of the FreeBSD mirror sites.

The freebsd-update(8) utility supports binary upgrades of i386 and amd64
systems running earlier FreeBSD releases. Systems running 7.0-RELEASE,
7.1-RELEASE, 7.2-BETA1, or 7.2-RC1 can upgrade as follows:

# freebsd-update upgrade -r 7.2-RC2

During this process, FreeBSD Update may ask the user to help by merging
some configuration files or by confirming that the automatically performed
merging was done correctly.

# freebsd-update install

The system must be rebooted with the newly installed kernel before continuing.
# shutdown -r now

After rebooting, freebsd-update needs to be run again to install the new
userland components, and the system needs to be rebooted again:

# freebsd-update install
# shutdown -r now

Linus Torvalds Switched Back To Gnome

Posted on in Categories Gnome, Kde, Linux, Linux desktop, Linux distribution, Linux laptop last updated January 24, 2009

Linus Torvalds, Linux’s creator, dislikes the GNOME desktop. There was a big flame war(s) between Linus Torvalds and the GNOME community. At one point he claimed that – “Gnome seems to be developed by interface Nazis and that its developers believe their users are idiots“. And guess what? Who made the switch to Gnome?

Linux Convert ext3 to ext4 File system

Posted on in Categories CentOS, Data recovery, Linux, Linux desktop, Linux distribution, RedHat/Fedora Linux, Storage, Suse Linux, Sys admin, Tips, Troubleshooting, Tuning, Ubuntu Linux last updated January 24, 2009

Some time ago ext4 was released and available for Linux kernel. ext4 provides some additional benefits and perforce over ext3 file system. You can easily convert ext3 to ext4 file system. The next release of Fedora, 11, will default to the ext4 file system unless serious regressions are seen. In this quick tutorial you will learn about converting ext3 to ext4 file system.

Vsftpd FTP Server With Virtual Users ( Berkeley DB + PAM )

Posted on in Categories CentOS, FTP Server, Howto, Linux, Networking, package management, RedHat/Fedora Linux, Security last updated February 18, 2011

VSFTPD supports virtual users with PAM (pluggable authentication modules). A virtual user is a user login which does not exist as a real login on the system in /etc/passwd and /etc/shadow file. Virtual users can therefore be more secure than real users, because a compromised account can only use the FTP server but cannot login to system to use other services such as ssh or smtp.