Delete

Stream Editor (sed) is a powerful command-line utility for transforming text in a pipeline. In this guide, we’ll explore how to delete lines from input files using the d command, covering non-destructive edits, specific-line removals, range deletions, and in-place updates.

Table of Contents

1. Overview of the d Command
2. Non-Destructive Deletion
3. Deleting a Specific Line
4. Deleting a Range of Lines
5. In-Place Deletion with -i
6. Quick Reference
7. Links & References

Overview of the d Command

The simplest way to remove lines in sed is with the delete script d:

sed 'd' employees.txt

This command reads every line and deletes it, producing no output.

Under the hood, sed follows this syntax:

sed [OPTIONS] SCRIPT [INPUT-FILE...]

• SCRIPT: A quoted set of editing commands (here, 'd').
• INPUT-FILE: One or more files to process (defaults to standard input).

Non-Destructive Deletion

By default, sed writes the transformed text to standard output and leaves the original file unchanged. To delete line 2 from employees.txt:

sed '2d' employees.txt

Output:

1|Kriti|Shreshtha|Finance|Financial Analyst|[email protected]|60000
3|Debbie|Miller|IT|Software Developer|[email protected]|80000
4|Enrique|Rivera|Marketing|Marketing Specialist|[email protected]|65000
5|Feng|Lin|Sales|Sales Manager|[email protected]|90000
6|Andy|Luscomb|IT|IT Manager|[email protected]|95000
7|Mark|Crocker|HR|HR Manager|[email protected]|85000
8|Jing|Ma|Engineering|Engineering Manager|[email protected]|100000

Your source file remains intact:

cat employees.txt

Deleting a Specific Line

To drop only the sixth line:

sed '6d' employees.txt

This command filters out line 6 from the output stream, leaving all others.

Deleting a Range of Lines

Use a comma-separated address pair to remove a block of lines:

sed '3,5d' employees.txt

This deletes lines 3 through 5.

In-Place Deletion with -i

To modify the file directly, add the -i (in-place) option:

# Inspect original
cat employees.txt

# Delete lines 2 through 7 and save changes
sed -i '2,7d' employees.txt

# Verify result
cat employees.txt

Resulting file:

1|Kriti|Shreshtha|Finance|Financial Analyst|[email protected]|60000
8|Jing|Ma|Engineering|Engineering Manager|[email protected]|100000

Quick Reference

Links & References

• GNU sed Manual
• Sed One-Liners Explained
• Shell Quoting Best Practices

By mastering these delete operations, you can efficiently cleanse, filter, or reorganize textual data in scripts and pipelines. Happy editing!