touch — Linux basic command

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A command that creates empty files or updates the modification time of existing files.

Basic Information

What Is This Command?

touch is a command that creates an empty file if it doesn't exist, and if it does, updates the file's access and modification times to the current time. It's the simplest method for file creation and is frequently used in scripts to create temporary files.

You can set a specific time with the -t option, or copy timestamps from another file with the -r option.

What Problem Does It Solve?

• Quickly creates empty files.
• Updates a file's modification time.
• Uses a timestamp file to mark task completion.
• Updates directory access times.

Key Features

Empty File Creation

Creates an empty file with a filename that doesn't exist.

• Use Case: When you need to create a file quickly.
• Result: A 0-byte empty file is created.
• Limitation: Since it's an empty file, data must be added separately.

Timestamp Update

Changes the modification time of an existing file to the current time.

• Use Case: When you want to mark a file as 'up-to-date'.
• Result: The current time will be shown in ls -l.
• Limitation: The file content remains unchanged.

Multiple File Creation

Specifies multiple filenames to create at once.

• Use Case: When creating multiple empty files at once.
• Result: All specified files are created.
• Limitation: If there are too many names, the command becomes long.

Time Specification (-t)

Sets a specific time with the -t option.

• Use Case: When manually setting backup or snapshot times.
• Result: The specified time is recorded in the file's metadata.
• Limitation: You need to know the exact time format.

Installation and Execution

Verify Pre-installation

It is included by default on all Linux distributions.

which touch
touch --version

Separate Installation (Lightweight Environments)

It is generally already installed.

sudo apt install coreutils   # Debian/Ubuntu

Practical Examples

Basic File Creation

Creates an empty file.

# Create a single file
touch empty.txt

# Create multiple files at once
touch file1.txt file2.txt file3.txt

# Verify
ls -l empty.txt
# -rw-r--r-- 1 user user 0 Oct 18 12:00 empty.txt

Timestamp Update

Changes the timestamp of an existing file.

# Update file timestamp to current time
touch existing-file.txt

# Verify timestamp
ls -l existing-file.txt

# Update directory timestamp
touch /var/www/html/

Specifying a Specific Time

Specifies the time using the -t option.

# Set to January 1, 2026 at 12:00
touch -t 202601011200 file.txt

# Copy timestamp from another file
touch -r reference.txt new-file.txt

# Verify timestamp
ls -l --time-style=full-iso file.txt