$ Linux One Liners
Back to commands

Hosting Operations

Read-only, can be slow

Find Pages Missing Canonical Links

You need to list generated HTML pages that do not include a canonical link.

Command

find public -name '*.html' -print | while read -r f; do grep -qi 'rel="canonical"' "$f" || echo "$f"; done

Before you run this

System impact: Read-only. Can create load on large logs, directories, filesystems, or process tables.

When not to use it: Do not use it to validate whether canonical URLs are correct; it only checks presence.

Expected output

A list of HTML files that lack rel="canonical".

System impact

Read-only, can be slow. Nothing changes. The command scans each HTML file and prints files missing canonical markup.

Scope this to the smallest useful path or service on busy systems.

Recovery / rollback: no state is changed.

When to use it

Use after layout edits, generator upgrades, or route additions.

When not to use it

Do not use it to validate whether canonical URLs are correct; it only checks presence.

Watch this command run

Command transcript

This sanitized transcript shows the commands and output shape without exposing host details.

demo@lab:~$

$ grep -Rni --include='*.html' 'rel="canonical"' public

public/draft.html:5:<link rel="canonical" href="https://example.com/draft.html">
public/blog/post.html:4:<link rel="canonical" href="https://example.com/blog/post.html">
public/index.html:5:<link rel="canonical" href="https://example.com/">

$ find public -name '*.html' -print | while read -r f; do grep -qi 'rel="canonical"' "$f" || echo "$f"; done

public/about.html
View commands shown

These are the commands shown in the sanitized transcript.

Commands shown

  1. grep -Rni --include='*.html' 'rel="canonical"' public
  2. find public -name '*.html' -print | while read -r f; do grep -qi 'rel="canonical"' "$f" || echo "$f"; done

next steps

Related commands

Hosting Operations Can be slow

Find Pages Missing og:title

Social previews often fail because one template missed Open Graph tags.

find public -name '*.html' -print | while read -r f; do grep -qi 'property="og:title"' "$f" || echo "$f"; done
Hosting Operations Can be slow

Find Pages Missing Meta Descriptions

Missing descriptions are usually a content template problem, not a mystery.

find public -name '*.html' -print | while read -r f; do grep -qi 'name="description"' "$f" || echo "$f"; done
Hosting Operations Can be slow

Find HTML Pages Missing from the Sitemap

A page can exist in the build but never make it into the sitemap.

find public -name '*.html' -print | sed 's#^public#https://example.com#' | while read -r url; do grep -q "$url" public/sitemap.xml || echo "$url"; done
Hosting Operations Can be slow

Find Feed Links Missing from the Sitemap

Your feed can advertise URLs that the sitemap never lists.

grep -o '<link>https://example.com/[^<]*</link>' public/feed.xml | sed 's#<link>##;s#</link>##' | while read -r url; do grep -q "$url" public/sitemap.xml || echo "$url"; done
Hosting Operations Can be slow

Find Logs Missing Logrotate Coverage

The biggest log risk is often the file no policy mentions.

find /var/log -type f -name '*.log' -printf '%p\n' | while read -r log; do grep -Rqs -- "$log" /etc/logrotate.conf /etc/logrotate.d || grep -Rqs -- "$(dirname "$log")/[*].log" /etc/logrotate.conf /etc/logrotate.d || printf '%s\n' "$log"; done
Study mapping

Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.

  • lpic1:103-gnu-unix-commands
  • lpic1:104-filesystems-permissions-fhs
  • lfcs:essential-commands
  • lfcs:operations-deployment
  • lfcs:services-logs
  • lfcs:storage
  • linuxplus:automation-scripting
  • linuxplus:provisional
  • linuxplus:system-management
  • risk:read-only

Useful for

  • LPIC-1 style command-line practice
  • LFCS style performance tasks
  • Linux+ style troubleshooting review

Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.