Text Processing (Grep/Sed/Awk)

Stop struggling with massive multi-line XML or JSON blobs

🧩 The Challenge

You ever try to grep a single field out of an XML dump that someone formatted into one giant, unending line? It’s like trying to find a needle in a haystack where the hay is moving.

💡 The Fix

Use grep with the -P flag to enable Perl-compatible regex and look-behinds, which lets you match patterns based on context rather than just raw strings. It turns a nightmare task into something you can actually read.

grep -oP '(?<=<target_tag>).*?(?=</target_tag>)' huge_dump.xml

⚙️ Why It Works

Perl-style regex supports zero-width assertions, meaning you can capture the content between tags without actually including the tags themselves in your output. You’re effectively slicing the string based on its surroundings.

🚀 Pro-Tip: Pipe the output into tr -d ‘\n’ if you’re pulling from multiple lines and need a clean CSV format.

Linux Tips & Tricks | © ngelinux.com | 9/30/2026