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Read the canonical tag of a page with curl

harmlessSEO checksdebian, ubuntu
Adjust the values, the command updates live
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curl -s https://example.com/ | tr '\n' ' ' | grep -oiE '<link[^>]*canonical[^>]*>'

Loads the HTML, joins it into a single line and prints the <link rel="canonical"> element. The canonical should point to the page’s own reachable URL with status 200, not to a redirect, a staging domain or the http variant. More than one line in the output indicates duplicate canonicals, which Google then ignores.

Note: A canonical can also be sent as an HTTP header Link: <...>; rel="canonical", which curl -sI {{URL}} | grep -i '^link:' shows.

Also searched as

  • check canonical url of a page
  • show rel canonical command line
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  • what is the canonical url of this page

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Check for soft 404s: does a missing page really return 404

$curl -s -o /dev/null -w '%{http_code} %{redirect_url}\n' https://example.com/diese-seite-gibt-es-nicht-$RANDOM
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Check maintenance mode for status 503 and Retry-After

$curl -s -o /dev/null -D - https://example.com/ | grep -iE '^(HTTP/|retry-after:)'
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Check the status code of all sitemap.xml URLs in parallel

$curl -s https://example.com/sitemap.xml | grep -oP '(?<=<loc>)[^<]+' | xargs -P 8 -I{} curl -o /dev/null -s -w '%{http_code} %{url_effective}\n' {} | grep -v '^200 ' | sort
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Check the X-Robots-Tag header of a URL

$curl -s -o /dev/null -D - https://example.com/ | grep -i '^x-robots-tag'
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Collect all URLs from a sitemap index

$curl -s https://example.com/sitemap_index.xml | grep -oP '(?<=<loc>)[^<]+' | xargs -n1 curl -s | grep -oP '(?<=<loc>)[^<]+' | sort -u
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Extract all URLs from a sitemap.xml

$curl -s https://example.com/sitemap.xml | grep -oP '(?<=<loc>)[^<]+' | sort -u
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