Table of Contents

The touch command updates file access and modification timestamps, and can create files that do not already exist. It is commonly used in build automation, file initialization, and timestamp management.

Overview

Use touch when you need to:

  • Create empty files quickly
  • Update modification/access times to current time
  • Apply specific timestamps to files
  • Align timestamps between files

Syntax

touch [options] file...

Common forms:

# Create file if it does not exist, else update timestamp
touch notes.txt

# Update timestamp without creating a new file
touch -c existing.txt

# Set explicit timestamp
touch -t 202606301200.00 report.txt

Common Options

Option Purpose Example
-a Change access time only touch -a file.txt
-m Change modification time only touch -m file.txt
-c, --no-create Do not create file if missing touch -c maybe.txt
-d STRING Parse date/time string (GNU) touch -d '2026-06-30 12:00' file.txt
-t STAMP Use [[CC]YY]MMDDhhmm[.ss] format touch -t 202606301200 file.txt
-r FILE Use timestamps from reference file touch -r src.txt dst.txt

Timestamp Basics

touch manages:

  • atime: last access time
  • mtime: last modification time

By default, both are set to current time (or file is created if missing).

Examples

# Create one empty file
touch todo.md

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

# Update only modification time
touch -m app.log

# Update only access time
touch -a app.log

# Set timestamp from explicit date/time (GNU)
touch -d '2026-06-30 08:30:00' report.csv

# Copy timestamps from another file
touch -r source.bin target.bin

# Do not create missing files
touch -c maybe-missing.txt

Build and Automation Use Cases

Trigger make-style rebuild behavior by changing mtime:

touch src/main.c

Initialize expected marker files:

mkdir -p .state
touch .state/initialized

Safe Usage Guidelines

  1. Use -c in scripts when file creation is not desired.
  2. Prefer explicit timestamps (-t or -d) for reproducible workflows.
  3. Verify timezone expectations in CI environments.
  4. Do not rely on timestamps alone for security-sensitive logic.

Troubleshooting

touch: cannot touch 'file': No such file or directory

Cause: Parent directory does not exist.

Fix:

mkdir -p parent
touch parent/file.txt

Timestamp did not change as expected

Possible causes:

  • Filesystem mount behavior (atime policies)
  • Option used (-a vs -m)
  • Incorrect date format

Fixes:

  • Validate with ls -l and stat
  • Use explicit options and known timestamp format

File was created unexpectedly

Cause: Default behavior creates missing files.

Fix:

touch -c file-that-may-not-exist

Notes

touch is lightweight but important for deterministic automation. Timestamp semantics can vary slightly by filesystem and operating system.

For command details and implementation-specific behavior, run:

man touch
touch --help
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