What is the Out-of-Memory (OOM) Killer and how to tune it?
OOMKiller is a mechanism for Linux systems to terminate processes when memory is exhausted to prevent crashes. It can protect critical processes from being killed by adjusting the oom_score_adj value, and optimize system-level memory management through overcommit settings. It is scored based on factors such as process memory usage and importance. The higher the score, the easier it is to be killed; to prevent key processes from being killed, the oom_score_adj can be set to -1000; the overcommit_memory policy can be adjusted at the system level, limit memory and swap usage, and monitor OOM events through dmesg. In Kubernetes or Docker environments, you need to pay attention to the interaction effect of resource quotas and cgroups.
Jul 11, 2025 am 12:12 AM
What is the purpose of the /etc, /var, and /tmp directories?
/etc stores system configuration files, such as /etc/ssh/sshd_config; /var saves logs, caches and other changes, such as /var/log and /var/cache/apt; /tmp provides temporary file storage, which may be cleared after restart. 1./etc contains static configuration, requires backup and strict permissions; 2./var requires regular log cleaning and monitoring; 3./tmp is not suitable for storing persistent data, and there may be security restrictions. These directories help with system management and troubleshooting.
Jul 10, 2025 am 11:54 AM
How to create a simple bash script in Linux
In Linux system, the steps to write a simple Bash script are as follows: 1. Create a script file and add a shebang line; 2. Write the command to be executed; 3. Give the script executable permissions; 4. Pay attention to path, syntax and debugging issues. First, use a text editor to create a file with an extension of .sh, such as myscript.sh, and add #!/bin/bash at the beginning of the file; then write specific commands, such as echo, ls-l and date, and use chmod xmyscript.sh to grant execution permissions; finally run the script through ./myscript.sh, and pay attention to check whether the path is correct, avoid syntax errors, and can pass bash-
Jul 10, 2025 am 11:53 AM
How to partition a new hard drive using fdisk or parted?
When you get a new hard disk and use fdisk or parted partition, just follow the steps. If you use fdisk, it is suitable for disks less than 2TB. The steps are: view the device name, start fdisk, create partitions, set partition type and size, and write changes; if you use parted, it is suitable for disks greater than 2TB or require GPT format. The steps include confirming the device, entering parted, setting the GPT partition table, creating partitions and exiting; finally, no matter which tool is used, the partition needs to be formatted and mounted.
Jul 10, 2025 am 11:52 AM
What is the difference between terraform plan and terraform apply?
Thedifferencebetweenterraformplanandterraformapplyisthat1)terraformplanpreviewschangeswithoutapplyingthem,while2)terraformapplyexecutesthechangestotheinfrastructure.Terraformplanactsasasafetycheckbyshowingintendedactionslikecreate,update,ordeletebase
Jul 10, 2025 am 11:45 AM
How to dual boot windows and linux
The key to installing a dual system is to correctly partition and set up boot. Prepare to install the USB disk in Linux and back up data; use the Windows disk management tool to compress the volume and make room for Linux; choose to coexist with Windows or manually partition during installation, mount point/at least 20GB and boot to the hard disk correctly; after restarting, select the system through the GRUB menu, if there is any problem, you can adjust it with the repair tool.
Jul 10, 2025 am 11:42 AM
How to define and call a function in a Bash script?
The key points of defining and calling functions in Bash scripts are as follows: 1. There are two forms of function definition, and it is recommended to use function_name(){...}; 2. The function must be defined first and then called, and the naming must be legal; 3. When calling, the function name is written directly, the parameters are separated by spaces, and the parameters are obtained through $1, $2, etc.; 4. The function cannot directly return the value, and the result can be passed through echo to capture the output, exit status code or global variables.
Jul 10, 2025 am 11:36 AM
What is the difference between exit and return in a script?
exit is used to terminate the entire script or session, return only exits the function or the called script. exit is used to completely stop scripts or shells, and returns status codes for other programs to check; return is used to return from function or source scripts, and does not affect the execution of the entire script. When using exit, the script completely ends and returns control; when using return, only the current function is exited and the script continues to run. Using exit in an interactive shell closes the session, and return can only be used within a function or source file. Select exit to apply to situations where global termination is required, and select return to apply to scenarios where local exit and return results.
Jul 10, 2025 am 11:31 AM
How to find the IP address and network interface configuration?
1. In Windows, you can use CMD to enter ipconfig or set interface to view the IPv4 address, subnet mask and default gateway; 2. Mac users can use the ifconfig command in the terminal or view TCP/IP information through network preference settings; 3. Under Linux, you can use the ipa or ifconfig command to view the interface configuration, and some systems need to install the net-tools package. Different systems can obtain IP address and network interface information through graphical interfaces or command lines, and can be completed quickly after familiarizing with the operation.
Jul 10, 2025 am 11:30 AM
What is Infrastructure as Code (IaC)?
InfrastructureasCode (IaC) is a method of defining and managing infrastructure through code, which can realize the automated deployment and management of servers, networks, storage and other resources. Its core value lies in improving the repeatability of environmental construction, supporting version control, saving time and cost, and promoting team collaboration. Mainstream tools include Terraform (multi-cloud platform), AWSCloudFormation (specially designed for AWS), Ansible (mainly configuration management), Pulumi (supporting a common programming language), and Chef/Puppet (focusing on server configuration). Getting started with IaC is: selecting platforms and tools, starting with simple resources, and learning to use Gi
Jul 10, 2025 am 11:24 AM
What are some best practices for securing an SSH server?
TosecureanSSHserver,implementstrongauthentication,limitaccess,changedefaultsettings,configurefirewallrules,andkeepthesystemupdated.First,enableSSHkeypairswithpassphrasesanddisablepasswordauthenticationentirelyafteruploadingpublickeystoauthorized_keys
Jul 10, 2025 am 11:23 AM
10 sFTP Command Examples to Transfer Files on Remote Linux
File Transfer Protocol (FTP) was a widely used protocol to transfer files or data remotely in an unencrypted format which is not a secure way to communicate. As we all know that File Transfer Protocol is not at all secure because all transmissions h
Jul 09, 2025 am 09:20 AM
How to Install OwnCloud on Rocky Linux and AlmaLinux
File sharing and collaboration is one of the key functions that users leverage on the Cloud in order to streamline workflows. This enables teams and users to get their projects done in a timely and convenient manner regardless of geographical distanc
Jul 09, 2025 am 09:19 AM
15 Practical Examples of 'echo' command in Linux
The echo command is one of the most commonly and widely used built-in commands for Linux bash and C shells, that typically used in a scripting language and batch files to display a line of text/string on standard output or a file. The syntax for the
Jul 09, 2025 am 09:18 AM
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