paste Command in Linux: Merge Lines of Files

Quick take: The paste command merges lines from files side by side into columns. paste a.txt b.txt joins them with a tab; -d sets a custom delimiter, and -s joins all lines of a file into one.

Introduction

The paste command is the column-wise counterpart to cat: instead of stacking files end to end, it places their lines side by side. This makes it ideal for building tables from separate lists, combining columns, or flattening a file into a single line.

Syntax

The basic syntax of the paste command is:

paste [OPTIONS] FILE...

Common Options and Parameters

The most useful options and parameters for the paste command:

Practical Examples

Real paste commands you can run today:

# Merge two files into columns
paste names.txt emails.txt
# Use a comma delimiter (make a CSV)
paste -d ',' names.txt emails.txt
# Join all lines of a file into one
paste -s -d ',' list.txt
# Combine three columns
paste col1.txt col2.txt col3.txt
# Turn command output into a single comma line
ls | paste -s -d ','

Tips and Best Practices

• paste -s -d ',' flattens a multi-line list into a single comma-separated line — handy for building arguments.
• Use -d with a delimiter to produce CSV or TSV directly from separate column files.
• paste matches lines by position, so the files should have the same number of lines for clean columns.

Final Thoughts

paste joins files column-wise, turning separate lists into tables or flattening a file into a single line with -s. Pair it with -d to produce CSV output and with cut to slice columns back out. Where cat stacks vertically, paste combines horizontally — a small but handy distinction.