How to use commands in linux

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

journalctl is a tool for viewing and managing logs in Linux, and is often used to troubleshoot service problems. 1. Use journalctl-u [service name] to view the specified service log, such as nginx.service; 2. Add the -f parameter to track log updates in real time; 3. Filter the log by time range through --since and --until, and support "today", "yesterday" or specific time points; 4. Use -b to view the last startup log, -b-1 to view the previous one, and -k to view the kernel log; 5. Other skills include: --pager-end automatically jumps to the end, -perr only sees error-level logs, and redirects output to files for easy analysis.

File system inconsistency can be fixed through standard tools. Linux uses fsck. 1. Uninstall the partition first, umount/dev/sdXn, 2. Run fsck/dev/sdXn or add -y parameters to automatically repair it. 3. The root partition needs to enter recovery mode or use LiveCD; Windows uses the chkdskC:/f/r command to handle it. The system may require a scan after restart. To reduce errors, it should avoid forced shutdown, regularly backup data, use UPS to prevent power outages, and regularly detect disk health. Frequent errors may be caused by aging of the hard disk.

Modifying the Hosts file is a practical skill, used to test websites, block advertisements, etc.; 1. Under Windows, you need to open Notepad with administrator permissions to edit C:\Windows\System32\drivers\etc\hosts; 2. Mac and Linux can be edited through the terminal command sudonano/etc/hosts; 3. If the DNS cache does not take effect after modification, Windows uses ipconfig/flushdns, Mac uses sudokillall-HUPmDNSResponder, Linux can restart network services or use systemd-resolve--flush-cach

To view the loaded kernel modules, 1. Use the lsmod command to list all loaded modules, their size and usage; 2. Use grep to filter specific modules such as lsmod|grepusb; 3. Use the modinfo module name to view the module details; 4. Use the cat/proc/modules file to obtain output similar to lsmod, suitable for script calls. These methods do not require complex operations, and some commands may require administrator permissions. If the expected module is not seen, it may be because the hardware is not connected or the function is not enabled.