1. File default Permissionsumask The Umask command is used to specify the default permissions when creating new files and directories. The default value for root umask is 022, and the average user's umask value is 002. Default permissions for new files =666-umask value new directory default permissions =777-umask value 2. Disk Management and file system Linux systems All devices are abstracted into files and stored in the/dev directory. The device name is generally hd[a-z] or sd[a-z], such as HDA, SDA, etc. IDE devices are typically HD prefixes, and SATA, SCSI, and USB devices are typically SD prefixes. 3. Partitioning: A disk is logically divided into zones, each of which is used as a separate disk for easy data and file management purposes. Currently, the main partitioning technologies are MBR and GPT. mbr:master Boot Record MBR is a traditional partitioning mechanism based on BIOS technology. The main features are: • Supports 32-bit and 64-bit systems • Limited number of supported partitions (up to 4 primary partitions) • Addressing 32-bit space, up to 2TB HDD gpt:guid Partition Table GPT is a new partitioning mechanism based on UEFI technology, and its main purpose is to solve the shortcomings of MBR mechanism. The main features are: • Support for drives larger than 2TB • Must use 64-bit system • Backwards compatible MBR current UNIX-like systems support GPT technology, and Windows systems support after Windows 7? Partitions in Linux are represented as: device name + partition number, such as SDA1. 4.Linux system Start-up process The startup process of the Linux system is: BIOS: Hardware boot • Basic input/output system, generally saved in the motherboard rom mbr:master boot Record linux boot process execute the first 446 bytes in the MBR Grub: The operating system Bootstrapper GRUB is a commonly used boot program in Linux distributions. Grub-related files are saved in the/boot/grub directory. The main configuration file is/boot/grub/grub.conf load kernel init: The first process init process is the Linux system running the first process its main functions include: Call/etc/rc.d/ Rc.sysinit files Initialize the system Mount file system start related services and programs based on RunLevel RunLevel: Related applications
linux02--file system and Disk Management
