Linux & Administration
Quota Management
File-system quotas are used to limit the amount of file system space a user or group can use. A user or group does not have a quota limit until one is set. When a GFS2 file system is mounted with the quota = on or quota = account option, GFS2 keeps track of the space used by each user and group even when there are no limits in place. GFS2 updates quota information in a transactional way so system crashes do not require quota usages to be reconstructed.
Red Hat Package Manager
With RPM, software is managed in discrete packages, a collection of the files that make up the software, and instructions for adding, removing, and upgrading those files. RPM also makes sure you never lose configuration files by backing up existing ones before overwriting. RPM also tracks which version of an application is currently installed on your system.
Linux Networking
The client selects a random unused 'source' port greater than 1024 and queries the server on the 'destination' port specific to the application. If it is an HTTP request, the client will use asource port of say, 1095 and query the server on port 80 (HTTP). The server recognizes the port 80 request as an HTTP request and passes on the data to behandled by the web server software.
File Transfer Protocol
File Transfer Protocol (FTP) is a common method of copying files between computer systems. Two TCP ports are used to do this: FTP Control Channel - TCP Port 21. All commands you send and the ftp server's responses to those commands will go over the control connection, but any data sent back (such as 'ls' directory lists or actual file data in either direction) will go over the data connection. FTP Data Channel - TCP Port 20 Used for all data sent between the client and server.
Network File System
Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems in 1984,allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed. NFS, like many other protocols, builds on the Open Network Computing Remote Procedure Call (ONC RPC) system. The Network File System is an open standard defined in RFCs, allowing anyone to implement the protocol.