1. concept analysis during linux Installation

1. Concepts encountered during linux installation linux is composed of kernel, Shell, file system, and linux tools. 1) All data in linux is presented as files. 2) mounting means to use a directory as the entry point and place the data in a disk partition under this directory. For mounting, we need to know the following two points. a) a single directory should not be mounted with multiple file systems. B) The directory as the mount point should theoretically be empty. If it is not empty, after a file system is mounted, the data in that directory will be hidden (not overwritten) until the mounted partition is detached. 3) in Linux, almost all hardware device files are stored in the/dev directory, for example, the file name of the Backup Device in Linux is IDE Hard Disk/dev/hd [a-d] SCSI/SATA/USB hard disk/dev/sd [a-p] U Disk/dev/ sd [a-p] (same as SATA) disk Drive/dev/fd [0-1] printer 25-pin:/dev/lp [0-2] USB:/dev/usb/lp [0-15] Mouse USB: /dev/usb/mouse [0-15] PS2:/dev/psaux current CDROM/DVDROM/dev/cdrom current mouse/dev/mouse tape drive IDE:/dev/ht0SCSI: /dev/st0 one sata hard disk is named sda and the other is sdb, instead of sdb. 4) Let's look at the disk partition. If we look at the hard disk in a long bar, then, we can look at the cylindrical column as a column chart, so the 64 bytes record segment. If the name of the hard disk device is/dev/hda, the file name of the device in the four partitions in Linux is shown as follows. The point is that the file name is followed by another number, this number is related to the location of the partition. P1:/dev/hda1P2:/dev/hda2P3:/dev/hda3P4:/dev/hda4 we assume that the hard disk has only 400 cylinders and is partitioned into four partitions, the fourth partition is in the range from 301st to 400. When your operating system is Windows, the first to fourth partition code should be C, D, E, F. When you have data to write to the f disk, your data will be written to 301 ~ of the disk ~ Between Cylinder 400. As the partition table only has 64 bytes, it can only accommodate up to four partitions. These four partitions are called Primary or Extended partitions. Based on the illustration and description above, we can get a few key information: in fact, the so-called "partition" is only used to set the 64 bytes partition table. 5) create a root directory partition and a sub-directory under the root directory. Someone has written a special article here. It is understood that during system installation, a space must be allocated on the hard disk. This special space is called root ), because you have installed a file system for this space when creating the root directory, the system will be able to find this space in the future. /Bin: stores the most common commands;/boot: starts the Linux core file (1. 100 m);/dev: Device File;/etc: stores various configuration files;/home: User's main directory (6. all remaining);/lib: the most basic dynamic link shared library of the system;/mnt: generally empty, used to temporarily Mount other file systems;/proc: virtual directory, is the memory ing;/sbin: the directory where the system administrator command is stored;/usr: the default software used to store the system is equivalent to the combination of c: \ windows and c: \ progarms; /usr/local: Save the software installed by yourself (4. 10g)/var: This directory stores frequently modified files. As the system runs more and more, including various logs and data files. (3. 5g) the red ones must be placed in the root directory partition. The smaller the other partitions that follow the root directory (/), the better (2. 15 GB), and the software installed by the application should not be in the same partition as the root directory. Currently, the partition is generally divided into/main partition 15 gswap swap memory two times home, the remaining partitions of the logical partition can be as you like. 6) after the installation is complete, the program obtained after the command line logon is shellshell independent of the kernel, which is similar to the general program. In fact, Shell is a command interpreter that explains the commands entered by the user and sends them to the kernel. After entering a command, shell completes the following tasks: 1. syntax analysis 2. Processing of-character redirection to pipeline and working mechanism 3. Searching and executing Shell also has a variety of different versions. bash is a well-known BASH: it is the GNU BourneAgain Shell, it is the default shell on the GNU operating system. Most linux distributions use this shell.