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This article is about how to quickly empty files under Linux. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

When working with files under the Linux terminal, sometimes we want to empty or delete the contents of the files directly but do not want to use any Linux command line editor to open them.

1. Clear the contents of the file by redirecting to Null

The easiest way to empty or make a file blank is to redirect null (things that don't exist) to the file through shell as follows:

# > access.log2. Use the 'true' command redirect to empty the file

Next we will use the: symbol, which is a built-in command for shell, which is equivalent to the true command, and can be used as a no-op (that is, to do nothing). Another way to empty a file is to redirect the output of: or true built-in commands to a file, as follows:

#: > access.log# true > access.log3. Use the cat/cp/dd utility and / dev/null device to empty the file

In Linux, the null device is basically used to discard output streams that are no longer needed by a process, or as a blank file of an input stream, which can usually be achieved by using the redirection mechanism, so the / dev/null device file is a special file that empties all inputs sent to it, while its output can be treated as an empty file. In addition, you can empty the file by displaying the contents of / dev/null using the cat command and then redirecting the output to a file.

# cat / dev/null > access.log

Next, we will use the cp command to copy the contents of / dev/null to a file for the purpose of emptying it, as shown below:

# cp / dev/null access.log

In the following command, if represents the input file and of represents the output file.

# dd if=/dev/null of=access.log4. Use the echo command to empty the file

Here, you can use the echo command to redirect the contents of the empty string to the file, as follows:

# echo "" > access.log or # echo > access.log

* * Note: * * you should remember that an empty string is not the same as null. A string indicates that it is a concrete thing, except that its content may be empty, but null means that something does not exist. For this reason, when you redirect the output of the echo command to a file as input and use the cat command to view the contents of the file, you will see a blank line (that is, an empty string). To input null into a file as output, you should use the-n option, which tells echo not to output the new line at the end like the command above.

# echo-n "" > access.log5. Use the truncate command to clear the contents of the file

Truncate can be used to shrink or expand a file to a given size. You can use it and the-s parameter to specify the size of the file. To empty the contents of the file, set the size of the file to 0 in the following command:

# truncate-s 0 access.log Thank you for reading! This is the end of the article on "how to quickly empty files under Linux". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!

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