#Crontab

[lowtechlinux]

Set up a printer Cronjob and bash script, step by step in detail

Daughter asked if there was a way to set up her new inkjet printer to print once a week to prevent the printer heads from drying out, much like her last printer had done. She really doesn’t want to buy a printer again just because she didn’t use it enough. I said “Absolutely. I can just set up a cronjob to print to it from my Linux computer and schedule that to print once a week. Problem…

[3v-hosting]

One of the most frequently used tools in the hands of a Linux-servers administrator is Cron. This is a utility that allows you to execute commands or run scripts according to a predetermined schedule. And there are a huge variety of tasks for which Cron is used. In this article, we will take a closer look at Cron, discuss the best practices for using it and the most common mistakes, and also look at a number of illustrative examples.

Read more

[ramniwas-sangwan]

Job Scheduling with At and Crontab in Linux | Automate Tasks Like a Pro!

[joy-jules]

DogCat - Exploiting LFI and Docker Privilege Escalation -TryHackMe Walkthrough

In this walkthrough, we’ll explore the Dogcat room on TryHackMe, a box that features a Local File Inclusion (LFI) vulnerability and Docker privilege escalation. LFI allows us to read sensitive files from the system and eventually gain access to the server.There are a total of 4 flags in this machine which we need to find. Let’s Dive in! Step 1: Scanning the Target Start by scanning the target…

[aistobascistod]

Omicron : Omigod :: crontab -e : godtab -e

[sentientcitysurvival]

Basic Linux Security (Updated 2025)

Install Unattended Upgrades and enable the "unattended-upgrades" service.

Install ClamAV and enable "clamav-freshclam" service.

Install and run Lynis to audit your OS.

Use the "last -20" command to see the last 20 users that have been on the system.

Install UFW and enable the service.

Check your repo sources (eg; /etc/apt/).

Check the /etc/passwd and /etc/shadow lists for any unusual accounts.

User the finger command to check on activity summaries.

Check /var/logs for unusual activity.

Use "ps -aux | grep TERM" or "ps -ef | grep TERM" to check for suspicious ongoing processes.

Check for failed sudo attempts with "grep "NOT in sudoers" /var/log/auth.log.

Check journalctl for system messages.

Check to make sure rsyslog is running with "sudo systemctl status rsyslog" (or "sudo service rsyslog status") and if it's not enable with "sudo systemctl enable rsyslog".

Perform an nmap scan on your machine/network.

Use netstat to check for unusual network activity.

Use various security apps to test you machine and network.

Change your config files for various services (ssh, apache2, etc) to non-standard configurations.

Disabled guest accounts.

Double up on ssh security by requiring both keys and passwords.

Check your package manager for any install suspicious apps (keyloggers, cleaners, etc).

Use Rootkit Scanners (chkrootkit, rkhunter).

Double SSH Security (Key + Password).

Disabled Guest Accounts.

Enabled Software Limiters (Fail2Ban, AppArmor).

Verify System Integrity via fsck.

Utilize ngrep/other networking apps to monitor traffic.

Utilize common honeypot software (endlessh).

Create new system-launch subroutines via crontab or shell scripts.

Ensure System Backups are Enabled (rsnapshot).

Check for suspicious kernel modules with "lsmod"

[onemanscienceband]

the other linux adventure last weekend was trying to get sdr++ to start on boot. i've never interacted directly with systemd stuff before and my impression so far is "way too complicated for regular users to touch".

like, to try to run a service on boot with systemd it was making a script that runs the server, testing that it works in userland, seting up the script as a service, configuring the service, and it still didn't work because my server threw some uninitialized variable error that never occurs in userland. i tried two or three times with no success, varying which states were in the "wanted" and/or "before" and "after" fields, no luck.

starting it up with cron was adding one line to a crontab and it Just Werked

[bugged-ubuntu]

Merry Crontab

[innovativeacademy-blog]

SYSTEM ADMIN INTERVIEW QUESTIONS 24-25

Table of Content

Introduction

File Permissions

User and Group Management:

Cron Jobs

System Performance Monitoring

Package Management (Red Hat)

Conclusion

Introduction

The IT field is vast, and Linux is an important player, especially in cloud computing. This blog is written under the guidance of industry experts to help all tech and non-tech background individuals secure interviews for roles in the IT domain related to Red Hat Linux.

File Permissions

Briefly explain how Linux file permissions work, and how you would change the permissions of a file using chmod. In Linux, each file and directory has three types of permissions: read (r), write (w), and execute (x) for three categories of users: owner, group, and others. Example: You will use chmod 744 filename, where the digits represent the permission in octal (7 = rwx, 4 = r–, etc.) to give full permission to the owner and read-only permission to groups and others.

What is the purpose of the umask command? How is it helpful to control default file permissions?umask sets the default permissions for newly created files and directories by subtracting from the full permissions (777 for directories and 666 for files). Example: If you set the umask to 022, new files will have permissions of 644 (rw-r–r–), and directories will have 755 (rwxr-xr-x).

User and Group Management:

Name the command that adds a new user in Linux and the command responsible for adding a user to a group. The Linux useradd command creates a new user, while the usermod command adds a user to a specific group. Example: Create a user called Jenny by sudo useradd jenny and add him to the developer’s group by sudo usermod—aG developers jenny, where the—aG option adds users to more groups without removing them from other groups. 

How do you view the groups that a user belongs to in Linux? 

The group command in Linux helps to identify the group a user belongs to and is followed by the username. Example: To check  user John’s group: groups john

Cron Jobs

What do you mean by cron jobs, and how is it scheduled to run a script every day at 2 AM? 

A cron job is defined in a crontab file. Cron is a Linux utility to schedule tasks to run automatically at specified times. Example: To schedule a script ( /home/user/backup.sh ) to run daily at 2 AM: 0 2 * * * /home/user/backup.sh Where 0 means the minimum hour is 2, every day, every month, every day of the week.

How would you prevent cron job emails from being sent every time the job runs? 

By default, cron sends an email with the output of the job. You can prevent this by redirecting the output to /dev/null. Example: To run a script daily at 2 AM and discard its output: 0 2 * * * /home/user/backup.sh > /dev/null 2>&1   

System Performance Monitoring

How can you monitor system performance in Linux? Name some tools with their uses. 

Some of the tools to monitor the performance are: Top: Live view of system processes and usage of resource htop: More user-friendly when compared to the top with an interactive interface. vmstat: Displays information about processes, memory, paging, block IO, and                CPU usage. iostat: Showcases Central Processing Unit (CPU) and I/O statistics for devices and partitions. Example: You can use the top command ( top ) to identify processes consuming too much CPU or memory.

In Linux, how would you check the usage of disk space?

The df command checks disk space usage, and Du is responsible for checking the size of the directory/file. Example: To check overall disk space usage:  df -h The -h option depicts the size in a human-readable format like GB, MB, etc.

Package Management (Red Hat)

How do you install, update, or remove packages in Red Hat-based Linux distributions by yum command?

In Red Hat and CentOS systems, the yum package manager is used to install, update, or remove software. Install a package:  sudo yum install httpd This installs the Apache web server.  Update a package: sudo yum update httpd Remove a package:sudo yum remove httpd 

By which command will you check the installation of a package on a Red Hat system?

The yum list installed command is required to check whether the package is installed. Example: To check if httpd (Apache) is installed:  yum list installed httpd

Conclusion

The questions are designed by our experienced corporate faculty which will help you to prepare well for various positions that require Linux such as System Admin.

Contact for Course Details – 8447712333

[codetoolshub]

Introducing Codetoolshub.com: Your One-Stop IT Tools Website

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And many more...

We are constantly updating and adding new tools to meet your needs. Visit Codetoolshub.com to explore and start using these powerful and free tools today!

Thank you for your support, and we look forward to helping you with all your IT needs.

[globalresourcesvn]

Hướng dẫn tạo crontab tự động backup với rclone với wasabi

💖👉🍀 Ok mình làm gọn cho bạn luôn nè, tạo crontab tự động backup với rclone rất dễ nhé! 🌟 Kế hoạch: Mỗi 1 tiếng tự động chạy lệnh rclone sync folder /home2/pickyour/public_html/wp-content/uploads/ lên Wasabi. Log kết quả ra file /var/log/rclone_wasabi.log để kiểm tra sau. ✅ Bước 1: Mở crontab crontab -e ✅ Bước 2: Thêm dòng sau vào cuối file: 0 * * * * /usr/bin/rclone sync…

[oeffentlicheversicherung]

Gibt es bereits jemanden, der buypass.com statt Let's Encrypt auf einem Server betreibt?

Bei https://www.buypass.com handelt es sich um ein Norwegisches Unternehmen aus Oslo, mit deren kostenlosen SSL Zertifikate Server abgesichert werden können.

Gullhaug Torg 2d, 0484 Oslo, Norwegen

Die Installation erfolgt mittels certbot und sieht übersichtlich aus.

Certbot installieren:

sudo apt update sudo apt install certbot

Bei Buypass CA registrieren: Registrieren Sie Ihre E-Mail-Adresse bei Buypass CA mit Certbot. Dieser Schritt ist notwendig, um ein Konto bei Buypass zu erstellen:

sudo certbot register --server 'https://api.buypass.com/acme/directory'

Sie werden aufgefordert, Ihre E-Mail-Adresse einzugeben und den Nutzungsbedingungen zuzustimmen. Alternativ können Sie eine Einzeiler verwenden, um diesen Prozess zu automatisieren:

sudo certbot register -m 'your-email@example.com' --no-eff-email --agree-tos --server 'https://api.buypass.com/acme/directory'

SSL-Zertifikat erhalten: Verwenden Sie Certbot, um das SSL-Zertifikat für Ihre Domain zu erhalten. Ersetzen Sie example.com durch Ihren tatsächlichen Domainnamen:

sudo certbot certonly --webroot -w /var/www/example.com/public_html/ -d example.com -d www.example.com --server 'https://api.buypass.com/acme/directory'

Dieser Befehl weist Certbot an, die Webroot-Methode zur Domain-Validierung zu verwenden und den Webroot-Pfad für Ihre Domain anzugeben1.

Automatische Erneuerung einrichten: Certbot kann Ihre Zertifikate automatisch erneuern. Um die automatische Erneuerung einzurichten, können Sie einen Cron-Job hinzufügen. Bearbeiten Sie die Cron-Jobs für den Root-Benutzer:

sudo crontab -e

Fügen Sie die folgende Zeile hinzu, um den Erneuerungsprozess zweimal täglich zu planen:

0 0,12 * * * /usr/bin/certbot renew --quiet

Dies führt den Erneuerungsprozess täglich um Mitternacht und Mittag aus und stellt sicher, dass Ihre Zertifikate immer aktuell sind.

#LetsEncrypt #buypass #sslzertifikat

Diese Angaben sind natürlich ohne Gewähr. Die Verwendung erfolgt auf eigene Gefahr.

[serverbill]

Let's EncryptでSSLを無料導入！Nginxと組み合わせてHTTPS化する手順

WebサイトやAPIの運用においてSSL（HTTPS）化は欠かせません。特にフォーム入力やログイン機能がある場合、通信の暗号化はユーザーの信頼を得る上で大きなポイントになります。 今回は無料で利用できるLet's Encryptを使用し、Nginxと組み合わせてSSL証明書を取得・設定する流れを解説します。

1. HTTPS化のメリット

通信内容の暗号化により盗聴や改ざんを防止

SEOに有利（GoogleがHTTPSを推奨）

ブラウザに「保護された通信」と表示されることで安心感を与える

2. Let's Encryptとは？

Let's Encryptは、無料でSSL証明書を発行してくれる認証局（CA）です。ACMEというプロトコルを通じて、自動で証明書を取得・更新できます。

3. 導入前提条件

サーバーにNginxがインストールされている

独自ドメインを保有しており、Nginxのサーバーに向けてDNS設定済み

80番ポート（HTTP）と443番ポート（HTTPS）が開放されている

4. Certbotを使ったSSL証明書の取得

以下はUbuntu系サーバーでの例です。sudo apt update sudo apt install certbot python3-certbot-nginx

証明書の取得とNginx設定の自動化:sudo certbot --nginx -d yourdomain.com -d www.yourdomain.com

インタラクティブな質問に答えていくだけで、自動で証明書取得とNginx設定が完了します。

5. 自動更新設定

Let's Encryptの証明書は90日間有効ですが、自動更新を設定しておけば安心です。sudo crontab -e

以下のような行を追加します（1日1回チェック）:0 3 * * * /usr/bin/certbot renew --quiet

6. NginxのSSL設定の例

server { listen 443 ssl; server_name yourdomain.com; ssl_certificate /etc/letsencrypt/live/yourdomain.com/fullchain.pem; ssl_certificate_key /etc/letsencrypt/live/yourdomain.com/privkey.pem; location / { proxy_pass http://localhost:8000; include proxy_params; } }

HTTPからHTTPSへのリダイレクトを設定したい場合は次のように追加します:server { listen 80; server_name yourdomain.com; return 301 https://$host$request_uri; }

まとめ

SSLの導入は以前に比べてはるかに簡単になりました。Let's EncryptとCertbotを使えば、無料かつ自動化された仕組みで、安全な通信環境をすぐに構築できます。 本サイトでも同様の手順でSSL化を行っており、サーバーコストを抑えつつ安全な配信を実現しています。

ブログがお役に立ったら Buy Me a Coffee ☕ で応援いただけたら嬉しいです。

[innvonixtech]

Unix Commands Every iOS Developer Should Know

When developing iOS applications, many developers focus primarily on Swift, Objective-C, and Xcode. However, a lesser-known yet powerful toolset that enhances productivity is Unix commands. Since macOS is a Unix-based operating system, understanding essential Unix commands can help iOS developers manage files, automate tasks, debug issues, and optimize workflows.

In this article, we’ll explore some of the most useful Unix commands every iOS developer should know.

Why Should iOS Developers Learn Unix?

Apple’s macOS is built on a Unix foundation, meaning that many system-level tasks can be efficiently handled using the terminal. Whether it’s managing files, running scripts, or automating processes, Unix commands can significantly enhance an iOS developer’s workflow. Some benefits include:

Better control over project files using the command line

Efficient debugging and log analysis

Automating repetitive tasks through scripting

Faster project setup and dependency management

Now, let’s dive into the must-know Unix commands for iOS development.

1. Navigating the File System

cd – Change Directory

The cd command allows developers to navigate between directories

{cd ~/Documents/MyiOSProject}

This moves you into the MyiOSProject folder inside Documents.

ls – List Directory Contents

To view files and folders in the current directory:

bash

CopyEdit

ls

To display detailed information, use:

bash

CopyEdit

ls -la

pwd – Print Working Directory

If you ever need to check your current directory:

bash

CopyEdit

pwd

2. Managing Files and Directories

mkdir – Create a New Directory

To create a new folder inside your project:

bash

CopyEdit

mkdir Assets

rm – Remove Files or Directories

To delete a file:

bash

CopyEdit

rm old_file.txt

To delete a folder and its contents:

bash

CopyEdit

rm -rf OldProject

⚠ Warning: The -rf flag permanently deletes files without confirmation.

cp – Copy Files or Directories

To copy a file from one location to another:

bash

CopyEdit

cp file.txt Backup/

To copy an entire folder:

bash

CopyEdit

cp -r Assets Assets_Backup

mv – Move or Rename Files

Rename a file:

bash

CopyEdit

mv old_name.txt new_name.txt

Move a file to another directory:

bash

CopyEdit

mv file.txt Documents/

3. Viewing and Editing Files

cat – Display File Contents

To quickly view a file’s content:

bash

CopyEdit

cat README.md

nano – Edit Files in Terminal

To open a file for editing:

bash

CopyEdit

nano config.json

Use Ctrl + X to exit and save changes.

grep – Search for Text in Files

To search for a specific word inside files:

bash

CopyEdit

grep "error" logs.txt

To search recursively in all files within a directory:

bash

CopyEdit

grep -r "TODO" .

4. Process and System Management

ps – Check Running Processes

To view running processes:

bash

CopyEdit

ps aux

kill – Terminate a Process

To kill a specific process, find its Process ID (PID) and use:

bash

CopyEdit

kill PID

For example, if Xcode is unresponsive, find its PID using:

bash

CopyEdit

ps aux | grep Xcode kill 1234 # Replace 1234 with the actual PID

top – Monitor System Performance

To check CPU and memory usage:

bash

CopyEdit

top

5. Automating Tasks with Unix Commands

chmod – Modify File Permissions

If a script isn’t executable, change its permissions:

bash

CopyEdit

chmod +x script.sh

crontab – Schedule Automated Tasks

To schedule a script to run every day at midnight:

bash

CopyEdit

crontab -e

Then add:

bash

CopyEdit

0 0 * * * /path/to/script.sh

find – Search for Files

To locate a file inside a project directory:

bash

CopyEdit

find . -name "Main.swift"

6. Git and Version Control with Unix Commands

Most iOS projects use Git for version control. Here are some useful Git commands:

Initialize a Git Repository

bash

CopyEdit

git init

Clone a Repository

bash

CopyEdit

git clone https://github.com/user/repo.git

Check Status and Commit Changes

bash

CopyEdit

git status git add . git commit -m "Initial commit"

Push Changes to a Repository

bash

CopyEdit

git push origin main

Final Thoughts

Mastering Unix commands can greatly improve an iOS developer’s efficiency, allowing them to navigate projects faster, automate tasks, and debug applications effectively. Whether you’re managing files, monitoring system performance, or using Git, the command line is an essential tool for every iOS developer.

If you're looking to hire iOS developers with deep technical expertise, partnering with an experienced iOS app development company can streamline your project and ensure high-quality development.

Want expert iOS development services? Hire iOS Developers today and build next-level apps!

[wingedmiraclesublime]

蜘蛛池优化需要哪些脚本技术？TG@yuantou2048

在互联网时代，搜索引擎优化（SEO）是网站获取流量的重要手段之一。而“蜘蛛池”则是SEO中的一种高级技术，它通过模拟搜索引擎的爬虫行为来提升网站的收录和排名。要实现高效的蜘蛛池优化，掌握一定的脚本技术是必不可少的。本文将介绍几种常用的脚本技术，帮助你更好地进行蜘蛛池优化。

1. Python 脚本

Python 是一种广泛应用于网络爬虫开发的语言，其简洁易用的语法和强大的第三方库支持使得它成为构建蜘蛛池的理想选择。使用 Python 可以轻松编写出功能强大的爬虫程序，如 Scrapy、BeautifulSoup 等库可以帮助开发者快速抓取网页信息，同时还可以利用多线程或多进程技术提高爬虫效率。此外，Python 还提供了丰富的数据分析工具，如 Pandas 和 NumPy，可以对抓取到的数据进行清洗和分析，从而为后续的优化工作提供数据支持。

2. JavaScript 脚本

JavaScript 不仅可以在浏览器端运行，也可以通过 Node.js 在服务器端执行。对于一些动态加载的内容，JavaScript 脚本能够有效地解析页面内容，提取所需信息。例如，你可以使用 Puppeteer 或 Selenium 库来模拟真实用户的浏览行为，确保爬虫能够正确处理 AJAX 加载的内容。

3. PHP 脚本

PHP 是后端开发人员常用的编程语言之一，在蜘蛛池优化中也有着广泛的应用。通过编写 PHP 脚本，可以实现对 JavaScript 渲染后的页面进行爬取，这对于那些依赖于 JavaScript 的网站尤其重要。利用 PhantomJS 或 Puppeteer 等工具，可以实现对动态页面的爬取。这些工具允许开发者控制浏览器环境，模拟用户操作，获取更全面的页面数据。

4. Shell 脚本

Shell 脚本通常用于自动化任务调度与管理。通过定时任务的方式定期执行特定的操作，比如更新 URL 列���、监控服务器状态等��结合 Linux 系统中的 crontab 功能，可以方便地设置定时任务，确保蜘蛛池能够持续不断地抓取最新内容。

5. Bash 脚本

Bash 脚本适合用来处理系统级别的任务，如自动重启服务、监控系统资源使用情况等。这对于维护一个稳定运行的蜘蛛池至关重要。例如，我们可以编写简单的 shell 脚本来自动化部署、监控及日志记录等功能，提高整个系统的健壮性与灵活性。

6. SQL 查询语句

虽然不是严格意义上的“脚本”，但熟练掌握 SQL 查询技巧同样重要。合理配置数据库连接参数，并编写相应的 SQL 语句来管理和维护蜘蛛池中的 URL 队列管理以及错误日志分析等工作流控制非常有用。

7. Perl 脚本

Perl 具有很强的文本处理能力，在处理大量数据时表现优异。利用 Perl 编写轻量级的脚本，可以高效地管理和调度爬虫任务，确保每个爬虫节点按照预定规则工作而不影响其他进程的正常运作。这有助于保持蜘蛛池的高可用性和稳定性。

8. Ruby 脚本

Ruby 是另一种流行的编程语言，特别适用于处理文本文件或执行复杂的字符串操作。当需要频繁地从数据库中读取或写入数据时尤为有效。它可以轻松地与其他语言集成在一起，实现自动化运维操作，如定时清理过期链接或者检查服务器状态等操作都十分便捷。

总结

综上所述，以上提到的几种脚本语言各有优势，在实际应用中根据具体需求选择合适的工具集将会极大地方便我们进行大规模数据抓取任务。总之，选择合适的编程语言和技术栈组合将极大地提升工作效率。当然还有更多其他类型的脚本语言可供选择，如 Ruby、Go 语言等也都有各自独特的优势。无论选择哪种方式，关键是要确保所有组件之间良好的协作机制，保证整个流程顺畅无阻塞地完成目标站点的抓取计划安排等复杂逻辑控制方面表现出色。因此，在构建自己的蜘蛛池时，请务必考虑多种语言混合使用场景下的性能问题。希望这篇文章能为你提供一些灵感！如果你有任何疑问或建议，请随时联系我 TG@yuantou2048 获取更多信息！

希望上述内容对你有所帮助！

加飞机@yuantou2048

EPP Machine

王腾SEO

[megid0nt]

@staff have a crontab on the single 1u blade this whole site is running on to execute "bad.sh" every morning at 11