5 Ways to Empty or Delete Files on Linux

Occasionally, while working on a file in the Linux terminal, you may want to empty the contents of the file without opening it using any Linux command line editor. How can this be achieved? In this article, we will empty the file contents in a few different ways with the help of some useful commands.
Warning : Before we go further into the various methods, please note that since everything is a file in Linux, you must make sure that the user files or system files you empty are not important. Empty contents are critical system files or configuration files that can cause fatal application/system errors or failures.
Having said all that, here's how to get into how to clear the contents of a file from the command line.
Important : We use the access.log file in the examples that follow in this article.

1. Empty the file by redirecting to Null

One of the easiest ways to empty the contents of a file is to use the shell to redirect null (non-existent objects) to the file as follows

# > access.log

 

Empty Large Files by Redirection in Linux

2. Empty files using "true" named redirects

Here we will use the notation  :  is also a shell built-in command, essentially equivalent to the  true  command, which can be used as a no-op.
Another way is to redirect the output of the builtin command  :  or  true  to a file like this:

# : > access.logOR # true > access.log

 

Empty large files using Linux naming

3. Empty File Using cat/cp/dd utilities with /dev/null

In Linux, a null device is basically used for discarding an unneeded output stream in a process, or a suitable empty file as an input stream. This is usually achieved through a redirection mechanism.
Therefore, the  /dev/null  device file is a special kind of file that will delete any input sent to it or output an empty file.
As an extension, you can clear the contents of a file by redirecting the output of  /dev/null  to a file using the  cat  name.

# cat /dev/null > access.log

 

Empty files using cat command

Next use the  cp  command to whitewash the file as follows:

# cp /dev/null access.log

 

Empty files using cat command

In the command below,  if  is the input file and  of  is the output file.

# dd if=/dev/null of=access.log

 

Empty files with dd command

4. Empty the file using the echo command

Here, we redirect to a file using the  echo  command and an empty string, as follows:

# echo "" > access.log

or

# echo > access.log

 

Use echo to name the empty file

Note : You should know that an empty string is not equal to null. String is already an object, it may be empty and null means non-existent object.
For this reason, when you use the  echo  command to redirect the above file, and use the  cat  command to view the contents of the file, a blank line (empty string) is output.
To send a null output to the file, use the flag -n which tells  echo  to not wrap the output after the output, whereas the preceding command produced an empty line.

# echo -n "" > access.log

 

Empty file using Null redirection

5. Empty the file named with truncate

The truncate  command helps to shrink or expand the file size to a defined size.

You can use the -s option to specify the file size. The next command clears the file contents by specifying a file size of 0:

# truncate -s 0 access.log

 

Truncate file in Linux

Now, in this article, we've covered multiple methods for clearing or emptying file contents using simple command line utilities and shell redirection mechanisms. But these may not be the only practical ways to do so.