Text Processing (Grep/Sed/Awk)

In-Place Log Sanitization with Sed

🧩 The Challenge

You need to redact sensitive API keys or passwords from multiple large log files without creating temporary files or using an external editor.

💡 The Fix

Use the stream editor in-place flag to perform regex substitution directly on the target files, effectively rewriting them while maintaining permissions.

sed -i 's/api_key=[A-Za-z0-9]*/api_key=REDACTED/g' /var/log/app/*.log

⚙️ Why It Works

The -i flag instructs sed to save changes to the original file instead of standard output, allowing for efficient bulk text replacement across directories.

🚀 Pro-Tip: Use the -i.bak suffix with sed to automatically create a backup of your original file before the substitution is applied.

Linux Tips & Tricks | © ngelinux.com | 7/6/2026