Novell LINUX ENTERPRISE SERVER 10 SP2 - INSTALLATION AND ADMINISTRATION Installation Manual page 448

IMPORTANT
Not all shells support ulimit directives. PAM (for instance, pam_limits)
offers comprehensive adjustment possibilities if you depend on encompassing
settings for these restrictions.
22.1.6 The free Command
The free command is somewhat misleading if your goal is to find out how much
RAM is currently being used. That information can be found in /proc/meminfo.
These days, users with access to a modern operating system, such as Linux, should not
really need to worry much about memory. The concept of available RAM dates back
to before the days of unified memory management. The slogan free memory is bad
memory applies well to Linux. As a result, Linux has always made the effort to balance
out caches without actually allowing free or unused memory.
Basically, the kernel does not have direct knowledge of any applications or user data.
Instead, it manages applications and user data in a page cache. If memory runs short,
parts of it are written to the swap partition or to files, from which they can initially be
read with the help of the mmap command (see man mmap).
The kernel also contains other caches, such as the slab cache, where the caches used
for network access are stored. This may explain differences between the counters in
/proc/meminfo. Most, but not all of them, can be accessed via /proc/slabinfo.
22.1.7 The /etc/resolv.conf File
Domain name resolution is handled through the file /etc/resolv.conf. Refer to
Chapter 33, The Domain Name System (page 615).
This file is updated by the script /sbin/modify_resolvconf exclusively, with
no other program having permission to modify /etc/resolv.conf directly. Enforc-
ing this rule is the only way to guarantee that the system's network configuration and
the relevant files are kept in a consistent state.
430 Installation and Administration