Touch Command in Linux In Hindi Mr Coder Rohit

Touch command

Linux Commands

The Touch Command in Linux

Any Linux system comes with a handful of tools pre-installed. The touch command is one such tool. The linux touch command is to modify the timestamps in the file metadata such as access and modification times. However, it’s also widely used for creating a new empty file in the desired location. With the proper file permission, the touch command can change the timestamps of any file. If the file didn’t exist prior, then it creates the file instead. In this guide, we’ll dive deeper into the usage of the touch command in Linux.

Prerequisites

To perform the steps demonstrated in this guide, you’ll need the following components.

• A machine running Linux. If you’re new to Linux, then consider using a virtual machine to experience it first. Learn more about installing and using Ubuntu in VirtualBox.
• Familiarity with the command line (or terminal). Check out some of the best terminal emulators for Linux.

The Touch Command Syntax

The core command structure of the touch command is as follows:

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$ touch <options> <file_or_dir_name>

This tool can work without any options provided. It also supports multiple options for advanced queries. Some options have abbreviated forms. If an option requires additional info, then it’s mandatory to provide.

The Touch Command Options

Here are some of the common options available for the touch command.

• –version or -v: Displays the program version.
• –help: Prints the help menu.
• -a: Changes the access time.
• -m: Changes the modification time.
• -no-dereference or -h: Change the timestamp of a symbolic link. Learn more about symbolic links in Linux.
• -c or –no-create: Not creating the file if it doesn’t exist.
• –date=<string> or –d=<string>: Timestamp is changed according to the date string.
• –reference=<file> or –r=<file>: Timestamp is changed according to the reference file.
• -t <stamp>: Changes the timestamp. Here, the stamp is in the date/time format.

File Timestamps

Before jumping further, you need to be aware of the different types of timestamps every single file has.

• Access time (atime): This timestamp keeps track of when the file was last read by any command, for example, grep and cat.
• Change time (ctime): This timestamp keeps track of the last time any property of the file was changed. Actions like file renaming, permission modification, or moving the file, etc. will change its value.
• Modification time (mtime): This timestamp tracks when the content of the file was last changed.

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To view the value of atime, use the following command:

$ ls -lu                                                                                                             

To view the value of ctime, use the following command:

$ ls -lc                                                                                               

To view the value of mtime, use the following command:

$ ls -l                                                                                                                                   

Using the Touch Command

We’ve covered all the basics of the touch command. It’s time to put them into action.

Creating a File

This is, by far, one of the most popular usages of the touch command. To create a new file, run the following command:

$ touch <file_name>

For example, create a new file test.txt:

$ touch test.txt

As mentioned earlier, if the file doesn’t exist, touch creates it automatically. Verify the change:

$ ls -l         

Creating Multiple Files

With the touch command, you can create multiple files at the same time. To do so, use the following command structure:

$ touch <filename_1> <filename_2>

For example, create two files test_1.txt and test_2.txt:

$ touch test_1.txt test_2.txt                                                                                   

Verify the changes:

$ ls -l                   

We can also create large batches of files (assuming the file names are sequential). To do so, enter the first and last element of the element in curly braces. For example, to create files test_1.txt to test_10.txt, use the following command:

$ touch test_{1..10}.txt

Verify the action:

$ ls -l

It also works for alphabets. For example, to create files test_a.txt to test_b.txt, use the following command:

$ touch test_{a..j}.txt

Verify the action:

$ ls -l

Setting Specific Timestamp

To set a specific timestamp to a file, the command structure is as follows:

$ touch -t <timestamp> <file_name>

The <timestamp> has a specific structure.

$ [[CC]YY]MMDDhhmm[.ss]

Here,

• CC: The first two digits of the year.
• YY: The last two digits of the year.
• MM: Month
• DD: Day of the month
• hh: Hour
• mm: Minute
• ss: Seconds

The items in the square brackets are optional. If the value of YY is 0-68, then CC is automatically assumed 20. If the value of YY is 69-99, then CC is assumed 19.

Let’s put it into action. Change the timestamp of test.txt to January 1, 1999 (12:00).

$ touch -t 199901011200 test.txt

Verify the changes:

$ ls -l --full-time test.txt

Setting Specific Timestamp Using Date String

A more comfortable way of changing the timestamp is by using the date strings. The syntax for using date strings is as follows:

$ touch -d <date_string> <file_name>

One benefit of using the date string is its flexibility. It supports various human-readable textual forms, for example,

• Relative times: “5 years ago”, “yesterday”, “next tuesday” etc.
• Calendar dates: “1 January 1969”, “2 February 2022” etc.
• Weekdays: “Sunday”, “Monday” etc.
• Time of day: “2:22am”, “12:22pm” etc.

Let’s change the timestamp of test.txt to “1 January 2011”.

$ touch -d "1 January 2011" test.txt

Verify the change:

$ ls -l --full-time test.txt

Changing File Access Time

There are two ways to change the atime of a file.

Changing file access time to current

The following touch command will set the access timestamp of the target file to the current time:

$ touch -a <file_name>

For example, change the atime of test.txt to the current time:

$ touch -a test.txt

Check the change:

$ ls -lu --full-time test.txt

Changing file access time explicitly

We can also specify the file access time explicitly. To do so, we’ll combine the “-a” and “-t” flags together. The command structure will look like this:

$ touch -at <timestamp> <file_name>

For example, the following command will set the file access time of test.txt to January 1, 1999:

$ touch -at 9901010000 test.txt                                       

Verify the change:

$ ls -lu --full-time test.txt

Changing Modification Time

Using the touch command, you can change the modification time (mtime) of a file. There are two ways of doing so.

Changing mtime to current

The following touch command will set the mtime of a file to the current time.

$ touch -m <file_name>

For example, change the mtime of test.txt to the current time:

$ touch -m test.txt

Verify the change:

$ ls -l --full-time test.txt

Changing mtime explicitly

We can combine “-m” and “-t” flags together to set a custom mtime. The syntax is as follows:

$ touch -mt <timestamp> <file_name>

For example, changing mtime to “1 January 1999” would look like this:

$ touch -mt 9901010000 test.txt

Verify the changes:

$ ls -l --full-time test.txt

Changing mtime and atime

With the touch command, we can use multiple options. Using this feature, we can set the mtime and atime of a file in a single command. The syntax would look like this:

$ touch -am <file_name>

Note that in this example, the time is changed to the current time. If you want a specific time, then you have to use the “-t” flag for a specific timestamp.

Avoid Creating New Files

If used with the flag “-c”, the touch command won’t create the file if it doesn’t exist.

$ touch -c <file_name>

Changing Timestamp Using a Reference File

We can tell touch to use the timestamps of a reference file. The command structure is as follows:

$ touch -r <reference_file> <file_name>

The target file will inherit the timestamps from the reference file.

Final Thoughts

The touch utility is a key terminal program when working with files in Linux. This tutorial demonstrates some general usage of the touch command. For more comprehensive details about the available options, check out the man page:

$ man touch

From <https://linuxhint.com/touch-command-linux/>