What is the Linux kernel and what does it do?
TheLinuxkernelmanagessystemresourcesandactsasabridgebetweenhardwareandsoftware.1)IthandlesprocessschedulingtodetermineCPUusage.2)Itmanagesmemoryallocationtopreventconflictsbetweenprograms.3)Itcommunicateswithhardwarethroughdrivers.4)Itorganizesdatast
Jun 20, 2025 am 12:42 AM
How to move or rename a file using the mv command?
The mv command is used to move or rename files, and its core lies in mastering basic syntax and precautions. 1. Use the "mv source path target path" when moving files, such as mv~/Desktop/report.txt~/Documents/; 2. Rename the file by changing the file name in the target path, such as mvold_name.txtnew_name.txt; 3. Pay attention to permission issues and use sudo to increase the authority if necessary; 4. The risk of overwriting the file can be avoided by adding the -i parameter; 5. Batch movement can list multiple source files and then connect to the target directory. Reasonable use of parameters can effectively prevent misoperation.
Jun 20, 2025 am 12:39 AM
How to check for failed SSH login attempts?
To check whether the server is subject to brute-force cracking or abnormal login behavior, you can view the SSH login failure record. In Debian/Ubuntu system, the log is located in /var/log/auth.log; in CentOS/RHEL, it is /var/log/secure. Use the command grep "Failedpassword" with the file path to filter failed attempts, and use --after or --since to define the time range. Common logs contain username, source IP, port and other information. If a certain IP appears frequently, it may be a scanning attack. For systemd system, journalctl_COMM=s
Jun 20, 2025 am 12:33 AM
How to compress a directory into a .tar.gz file?
To compress the directory to .tar.gz file, use the tar command. The basic format is tar-czvf output file name.tar.gz directory path to compress, such as tar-czvfbackup.tar.gzmy_folder; the -v parameter can be removed to achieve static compression; 1. Use the --exclude parameter to exclude specified files or directories, such as tar-czfbackup.tar.gz--exclude=my_folder/logsmy_folder; 2. Multiple files or directories can be excluded by using the --exclude parameter multiple times; 3. Pay attention to the correctness of the path during operation, and use the relative path or absolute path to specify the directory location; 4
Jun 20, 2025 am 12:32 AM
How to install software on Ubuntu using apt?
How to install software using apt on Ubuntu includes: 1. Update the software source list to ensure the latest information is obtained; 2. Use the sudoaptinstall command to install the required software; 3. Find and view software details through aptsearch and aptshow; 4. Use sudoaptrymove or purge to uninstall the software; 5. Clean useless dependency packages regularly. Mastering these basic commands allows you to efficiently manage software.
Jun 20, 2025 am 12:27 AM
What is awk and what are some common use cases?
Awkisapowerfultext-processingtoolusedinUnixandLinuxenvironmentsfordataextractionandreporting.Itreadsinputlinebyline,splitseachlineintofields,andallowsmanipulationusingpatternsandactions.1.Awkexcelsatfilteringlogfilesbasedonconditions,suchasfindingHTT
Jun 20, 2025 am 12:27 AM
What is the difference between a hard link and a symbolic (soft) link?
Hardlinksandsymbolic(soft)linksaretwodistinctmethodsforreferencingfilesinUnix-likesystems,eachwithuniquecharacteristics.1.Hardlinksdirectlypointtoafile’sinode,allowingmultiplefilenamestoreferencethesamedata;deletingonenamedoesn’tremovethedataaslongas
Jun 20, 2025 am 12:23 AM
How to view systemd logs with journalctl?
How to view systemd logs? Use the journalctl command. journalctl is a powerful tool for querying and displaying systemd logs, providing structured log data. 1. Run journalctl to view all logs; 2. Add -x parameters to improve readability; 3. Use --since and --until to filter logs by time; 4. Use -u parameters to add service names to view specific service logs; 5. Use -b or --list-boots to view different startup logs; 6. Use -f parameters to monitor logs in real time. Proficiency in these techniques can help quickly troubleshoot system problems.
Jun 20, 2025 am 12:18 AM
How to schedule a recurring task using cron?
To set up periodic tasks using Linux cron, first open the crontab editor and enter the command crontab-e (use sudocrontab-e for system-level tasks); secondly, master the five-segment cron expression, such as 306* means to execute tasks at 6:30 every day; then optionally set environment variables and logging to avoid execution problems, such as defining SHELL, PATH and LOGFILE, and redirecting the output to the log; finally view the task through crontab-l and clear the task through crontab-r. If the task is not executed, you can view the system log to troubleshoot problems.
Jun 20, 2025 am 12:14 AM
How to check if a specific port is open and listening?
To confirm whether a specific port is open and listen, 1. Use sudonetstat-tuln|grep: or sudoss-tuln|grep: on Linux/macOS; 2. Run netstat-an|findstr: on Windows; 3. Check that the remote host can use telnet or nc-zv to test the connection, and if successful, the port will be open. These methods can effectively determine the listening status of local or remote ports.
Jun 20, 2025 am 12:06 AM
How to Compress a Video on Mac
Video files take up more space on average than music, photos, documents, and almost any other type of file you might keep on your Mac. In an era of 4K screens and smartphone cameras, these file sizes allow us to enjoy i
Jun 19, 2025 am 11:01 AM
How to Install OpenSSH Server from Source in Linux
OpenSSH is a free and open source, full implementation of the SSH protocol 2.0, which provides a number of tools for securely accessing and managing remote computer systems, and managing authentication keys, such as ssh (a secure replacement for teln
Jun 19, 2025 am 10:50 AM
iOS 15.7.1 & iPadOS 15.7.1 Released with Security Updates
Apple has released updates for iPhone and iPad users who continue to run the iOS 15 and iPadOS 15 operating systems. The updates are versioned as iOS 15.7.1 and iPadOS 15.7.1 for iPhone and iPad, respectively. These updates are available separately f
Jun 19, 2025 am 10:48 AM
iOS 16.1 RC & iPadOS 16.1 RC Released for Beta Testers
Apple has made available the release candidate (or golden master) versions of iOS 16.1 and iPadOS 16.1 for participants in the beta testing programs for iPhone and iPad system software.Release Candidate (RC) versions are generally the last stage in a
Jun 19, 2025 am 10:45 AM
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