Bash touch - Change File Timestamps
Using the touch Command
The touch command is used to change file timestamps or create an empty file if it doesn't exist.
It's often used to create placeholder files or update timestamps for build systems.
Basic Usage
To update the access and modification times of a file, use touch filename:
Example
touch file.txtOptions
The touch command has options to change how it works:
-a- Update only when the file was last read-m- Update only when the file was last changed-t- Set the timestamp to a specific time-c- Do not create any files
-a Option: Change Access Time
The -a option lets you update the access time of a file.
Example: Change Access Time
touch -a file.txt-m Option: Change Modification Time
The -m option lets you update only the modification time of a file.
Example: Change Modification Time
ls -l
-rw-r--r-- 1 user 197609 208 Apr 9 06:24 my_file.txt
touch -m my_file.txt
ls -l
-rw-r--r-- 1 user 197609 208 Apr 9 08:25 my_file.txt-t Option: Set Specific Timestamp
The -t option allows you to set the timestamp to a specific time.
Example: Set Specific Timestamp
ls -l
-rw-r--r-- 1 user 197609 208 Apr 9 06:24 my_file.txt
touch -t 202501010000 my_file.txt
ls -l
-rw-r--r-- 1 user 197609 208 Jan 1 00:00 my_file.txt-c Option: Do Not Create Files
The -c option tells touch not to create any files if they do not exist.
This is useful when you want to update timestamps without accidentally creating new files.
Example: Do Not Create Files
touch -c non_existent_file.txtUsing touch with Wildcards
Wildcards allow you to update timestamps on multiple files at once.
For example, touch *.txt will update the timestamps of all text files in the directory.
Example: Using Wildcards
touch *.txt
