Introduction

In Linux, every file contains metadata that includes several timestamps:

  • Access time (atime) — Last time the file was read.
  • Modification time (mtime) — Last time the file’s content was changed.
  • Change time (ctime) — Last time the file’s metadata (e.g., permissions, ownership) was changed.
  • Birth time — The file’s creation time (available only on certain filesystems and kernels).

The touch command is commonly used to update the access and modification times. However, note that Linux does not allow modification of the birth (creation) time using standard tools.

Prerequisites

To follow this guide, ensure:

  • A Linux system (e.g., Ubuntu, Debian, CentOS)
  • Terminal access with necessary permissions (sudo or root)
  • The touch command is available (default on all major distributions)
  • Understanding of the touch timestamp format

Timestamp Format: [[CC]YY]MMDDhhmm[.ss]
Example: 202404200101.00 → April 20, 2024, at 01:01:00 AM

Steps to Modify File Date (Access and Modify Time)

1. Create a file

touch new.txt

2. Modify access and modification times

touch -a -m -t 202404200101.00 new.txt

3. Verify the changes

stat new.txt

Expected Output:

Access: 2024-04-20 01:01:00.000000000 +0000
Modify: 2024-04-20 01:01:00.000000000 +0000
Change: [current time]
Birth: [unchanged, if supported]

Important Limitation: Birth Time

  • Birth (creation) time cannot be changed using touch or most Linux utilities.
  • Most Linux filesystems (like ext4, xfs, btrfs) do not support birth time editing.
  • Even when visible, this field is read-only and primarily informational.
  • Some environments may simulate birth time, but true modification is not possible with common tools.

Conclusion

Using the touch command, you can manipulate mtime and atime to simulate past activity or modify metadata for auditing or testing purposes. However, modifying the birth timestamp is not supported due to limitations in Linux filesystem designs. For practical purposes, focus on mtime and atime, which are both fully controllable.

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