How to use the Linux sed command to delete a range of lines

By Alvin Alexander. Last updated: February 1, 2024

In a previous blog post I demonstrated how to use the 'sed' command to insert text before or after a line in many files, and in this example I’ll show how to delete a range of lines using the sed command.

sed delete: How to delete a range of lines using sed

The problem I had today was that I just re-generated 99 HTML files for my Introduction to Unix/Linux tutorial using Latex2HTML, and it generates a bunch of “junk” in my HTML files that looks like this:

<a name="CHILD_LINKS"></a>
<ul>
<li><a name="tex2html5"
  href="node1.shtml">Contents</a>
<li><a name="tex2html6"
  href="node2.shtml">Introduction</a>
//
// this goes on for a long, long time ...
//
// it finally ends with this line:
<!--End of Table of Child-Links-->

Knowing that I want to delete this entire range of lines in all my generated HTML files, I used the following sed script to delete the range of lines, using this one sed command:

/\<!--Table of Child-Links-->/,/<!--End of Table of Child-Links-->/d

With this sed command, I start deleting lines in each file when I saw the first line pattern:

<!--Table of Child-Links-->

and then I stop deleting lines after seeing the ending line pattern:

<!--End of Table of Child-Links-->

Before running this sed command at all, I of course made a backup of all my files.

Then, after making that backup, I saved my sed command to a file named changes.sed:

/\<!--Table of Child-Links-->/,/<!--End of Table of Child-Links-->/d

As mentioned in my earlier article, I then tested my change by running the following command, and then visually verifying the output:

sed -f changes.sed < node2.shtml | more

A Linux shell script to change all the files with sed

Once I was sure that my sed command had properly deleted the range of lines in that test case, I wrote a simple Linux shell script to run the sed command on every “node*.html” file in the current directory, like this:

# change all the "node*.html" files in the current directory

for i in `ls node*html`
do
  echo "working on $i ..."
  sed -f changes.sed < $i > ${i}.tmp
  mv ${i}.tmp $i
done

I saved this shell script to a file named go.sh, and then ran it like this:

sh go.sh

After my shell script ran, I checked some of my files, and verified that the sed script/command had successfully deleted that range of lines in all 99 files. The sed script worked fine, deleting the range of lines as desired, and life is good.

linux-unix

delete