Why does linux need mmu

To create an LVM volume group, you must first prepare a physical volume (PV) and then create a VG. 1. Use pvcreate to initialize the hard disk or partition into PV, such as pvcreate/dev/sdb1; 2. Use the vgcreate command to combine one or more PVs into VG, such as vgcreatemy_volume_group/dev/sdb1/dev/sdc1; 3. You can customize the PE size through the -s parameter and use vgdisplay to view information; 4. You can dynamically expand VG in the future and add a new PV using vgextend; 5. Before deleting VG, you must confirm that there is no LV and delete it with vgremove.

The key to managing environment variables is to use .env files to centrally manage, distinguish different environment configurations, inject variables during deployment, and avoid hard-coded sensitive information. Specific practices include: 1. Use .env files to store variables and distinguish them by environment, such as .env.development and .env.production, and add .gitignore; 2. Use NODE_ENV and other identifiers to determine the corresponding configuration of the current environment to automatically load; 3. Inject variables at the system level when deploying servers, Docker or cloud platforms to improve security; 4. All sensitive information must be obtained from environment variables, the naming must be clear, and can be managed in combination with encryption means or special tools.

Efficiently managing AzureVM requires mastering three aspects: creation configuration, performance monitoring and cost optimization, and backup security management. First, select the right region and official support system image when creating, use independent VNet on the network, restrict open ports and enable NSG, and enable start-up diagnostics at the same time; secondly, use AzureMonitor to view resource utilization, set timed power on and off, automatic scaling, give priority to using reserved instances, and select disk types according to needs to save costs; finally, use Backup service regularly for backup, set the retention period to more than 30 days, and regularly update patches in terms of security, use the "Security Center" to scan vulnerabilities, avoid logging in with an administrator account and turning on disk encryption to ensure data security.

Linux monitoring involves a variety of tools, system performance monitoring tools include top/htop real-time viewing of resource usage, vmstat displays virtual memory status, iostat detects disk IO bottlenecks, and sar records historical performance data. The log monitoring tool includes journalctl filtering service logs, dmesg debugging kernel issues, logrotate management log life cycle, and rsyslog/syslog-ng centralized forwarding logs. In terms of network monitoring, SS/NNSTAT checks the connection status, NMap scans open ports, TCPDump captures traffic analysis, and iftop monitors bandwidth usage. Remote monitoring solutions such as Nagios implement deep custom alarms, Zab

Resetting the root password of Linux system can be achieved by the following methods: 1. Single-user mode is suitable for situations with startup permissions. After restarting, editing the kernel parameters into the command line environment. Use rd.break or init=/bin/bash according to the distribution, and then executing the mount, chroot and passwdroot commands to complete the password modification; 2. LiveCD/USB is suitable for mounting the original system partition and chroot and then executing passwdroot. Note that multiple directories may need to be manually mounted; 3. Ubuntu/Debian can use recoverymode, and select this option in the GRUB menu to enter rootshell to modify the password.

Using job control in Bash can be achieved through several basic commands and shortcut keys. First, make sure that job control is enabled, you can check the output set-m confirmation; then use Ctrl Z to pause the foreground task and use bg to transfer it to the background operation; view all task status through jobs; use fg%n to switch the specified task to the foreground; use kill%n to terminate the task; finally pay attention to distinguishing PID from job number, and use nohup or disown to protect the background task before closing the terminal.

rsync is an efficient file transfer tool suitable for large number of files or synchronous update scenarios. It supports breakpoint continuous transmission, compressed transmission, permission retention and other functions. The basic command format is rsync[option] source path target path, common options include -a (archiving mode), -v (display progress), -z (compressed transmission), and -P (display progress and support breakpoint continuous transmission). For example: rsync-avz/home/user/data//backup/data/. Remote transmission can be implemented through user@remote:/remote/path, and supports SSH keys to be logged in without password. 1. Use --backup and --su

The steps for configuring VLAN in Linux system include: 1. Install necessary software packages, such as sudoaptinstallvlan for Debian/Ubuntu, and sudoyumininstallvconfig for CentOS/RHEL; 2. Load the kernel module, run sudomodprobe8021q and configure automatic loading on the computer; 3. Create a VLAN interface, such as sudoiplinkaddlinketh0nameeth0.10typevlanid10; 4. Assign IP addresses and enable interfaces; 5. Save configurations persistently and modify /etc/network/inte in Debian/Ubuntu