The /usr/local Directory
“The /usr/local hierarchy is for use by the system administrator when installing software locally. It needs to be safe from being overwritten when the system software is updated. It may be used for programs and data that are shareable amongst a group of hosts, but not found in /usr.”
The /usr/local directory is similar in structure to the /usr directory. It has the following subdirectories, which are similar in purpose to those in the /usr directory.
/usr/local
|- bin
|- doc
|- etc
|- games
|- include
|- lib
|- libexec
|- sbin
|- share
|- src
Pros and Cons of Lightweight Directory Access Protocol (LDAP)
The main benefit of using LDAP is the consolidation of certain types of information within your organization. For example, all of the different lists of users within your organization can be merged into one LDAP directory. This directory can be queried by any LDAP-enabled applications that need this information. It can also be used by users who need directory information.
Other LDAP benefits include its ease of implementation (compared to X.500) and its well-defined Application Programming Interface (API), which means that the number of LDAP-enabled applications and LDAP gateways should increase in the future.
On the negative side, if you want to use LDAP, you will need LDAP-enabled applications or the ability to use LDAP gateways. While LDAP usage should only increase, currently there are not very many LDAP-enabled applications available for Linux.
When the kernel loads, it immediately initializes and configures the computer’s memory. Next it configures the various hardware attached to the system, including all processors and I/O subsystems, as well as any storage devices. It then looks for the compressed initrd image in a predetermined location in memory, decompresses it, mounts it, and loads all necessary drivers. Next it initializes file system-related virtual devices, such as LVM or software RAID before unmounting the initrd disk image and freeing up all the memory it once occupied.
After the kernel has initialized all the devices on the system, it creates a root device, mounts the root partition read-only, and frees unused memory.
At this point, with the kernel loaded into memory and operational. However, with no user applications to give the user the ability to provide meaningful input to the system, not much can be done with it.
To set up the user environment, the kernel starts the /sbin/init command.
Mounting confusion /proc comes to the rescue
If you are losing track of what’s mounted, and in what state? No problem, here comes /proc to the rescue:
This displays all mounted filesystems, the filesystem types, read/write status, and other attributes. How many hard drives are on the system? One of these will tell you and also, SCSI drives are sd, IDE are hd.
or
or
Cloning an entire drive
You’ll need two hard drives the same size, or a destination drive larger than the source drive.
Make sure no partitions are mounted on either drive. In this example /dev/hda is the source drive, /dev/hdb is the destination drive. The dd command makes an exact, byte-for-byte copy, including the MBR (master boot record):
# dd if=/dev/hda of=/dev/hdb
