Configure Postfix to Send Email Using External SMTP Servers
Configure Postfix to relay emails through external SMTP servers like Brevo, Mailgun, or Amazon SES. Step-by-step setup guide with an automated script.
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Category: Linux
Page 4 of 5 — 46 guides in this category
How to Secure an SSH Server in Linux: Hardening Guide
Secure your Linux SSH server with this hardening guide. Covers key-based auth, sshd_config best practices, fail2ban, firewall rules, and OpenSSH security.
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100+ Essential Linux Commands You MUST Know (2026 Guide)
Master the Linux command line with this cheat sheet of 100+ essential Linux commands.
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Fix Cannot Open Packages Database In /var/lib/rpm DB_RUNRECOVERY: Fatal error
Learn how to fix the common Cannot Open Packages Database In /var/lib/rpm DB_RUNRECOVERY: Fatal error and install packages.
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Add a New Drive to Ubuntu LVM and Mount It Permanently
Add a new drive to Ubuntu LVM: pvcreate, vgcreate, lvcreate, ext4 format, and persistent mount with fstab nofail. Step-by-step guide for Ubuntu 24.04.
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Extract Text From PDF on Linux Command Line (pdftotext)
Extract text from PDF files on Linux command line using pdftotext. Covers install, layout modes, password-protected PDFs, OCR for scanned docs & batch scripts.
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How to Merge PDF Files on Linux Command Line (pdfunite)
Merge PDF files on Linux command line with pdfunite from poppler-utils. Covers installation, usage, alternatives (qpdf, Ghostscript), and troubleshooting.
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Sed Delete Lines: Advanced Techniques & Practical Examples
Master the sed delete line command: remove lines by number, pattern, and range, avoid GNU vs BSD pitfalls, and clean log files safely. Updated 2026 examples.
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Sed Search and Replace: Master Advanced Techniques
Master sed search and replace with practical examples: the substitute (s) command, regex patterns, in-place edits, and GNU vs BSD portability tips for 2026.
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How to Check Remote Ports Using the nc Command in Linux
Learn how to check if remote ports are open using the nc (netcat) command in Linux. Covers TCP/UDP testing, port ranges, timeouts, and scripting patterns.
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