pagefind_dcd{"url":"/blog/201305190715_sed_convert_matches_lowercase.html","content":"tinyapps.org / blog. sed - convert regex pattern matches to lowercase # In this example, we'll convert text within bold tags to lowercase. Let's have a look first to make sure our search pattern returns the desired results: $ grep '<b>.*<\\/b>' foo.html <p><a href=\"/\">tinyapps.org</a> / <b>Graphics</b></p> <p><b>Viewing & Editing</b></p> <p><b>Measuring</b></p> <p><b>Optimizing</b></p> <p><b>Screen Capture</b></p> <p><b>Fonts</b></p> <p><b>Other</b></p> Next, a test run, sending output to stdout: $ sed 's/<b>.*</b>/\\L&/g' foo.html As expected, all characters between bold tags were converted to lowercase. (In the replacement pattern, \"&\" corresponds to the pattern found, and \"\\L\" converts the text to lowercase.) Now let's use -i to write the changes in place (apparently introduced around GNU sed version 4): $ sed -i 's/<b>.*</b>/\\L&/g' foo.html For batch processing multiple files: $ grep '<b>.*<\\/b>' *.html ... $ for i in '*.html'; do sed -i \"s/<b>.*</b>/\\L&/g\" $i; done Two related tips by Karoly: 1. Use double quotes so the shell can substitute variables. 2. If your search or replace string contains special characters you need to escape them. /nix | May 19, 2013. RSS | Archives.","word_count":176,"filters":{},"meta":{"title":"sed - convert regex pattern matches to lowercase #"},"anchors":[]}