How to create an empty file from command line

Question

How can I create an empty file from the command line?

Answer 1

Use the touch command:

The touch utility sets the modification and access times of files to the
current time of day. If the file doesn't exist, it is created with
default permissions.
A FILE argument that does not exist is created as an empty file by the
touch command, unless the -c option is supplied.

Example:

touch newfile

Answer 2

> newfile

Will also create an empty file. If the file does already exist, it will be truncated (emptied). To keep the file contents, use >> for appending as in:

>> file

Even if the file exists, the contents will be untouched.

Edit: If you don't have any content to type, this one is faster:

user@host$ :> newfile
user@host$ :>> new_or_existing_file

Note. : is the command here. It is not part of the prompt.

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If you want to create as root

: | sudo tee thefile

To not truncate existing file:

: | sudo tee -a thefile

Answer 3

cat /dev/null > file1.ext 

the exact way there is also another way

echo "" > file2.ext 

The difference is file1.ext will be zero bytes and file2.ext would be one byte. You can check this by

ls -l file*.*

Answer 4

Using vim editor you can also create an empty file.

vim filename

Then save

:wq

Answer 5

The command

echo -n > file

creates an empty file, if your version of echo supports the -n switch.

Or you could use printf

printf '' > file

Answer 6

In general, creating any regular¹ file on Linux involves open(2) ,openat(2), and creat(2) system calls (and specifically with O_CREAT flags). That means if you call any command-line utility that does these system calls, you can create a new empty file.

Most commonly new filename is created with something like this:

• touch /tmp/new_file
• : > /tmp/new_file
• true > /tmp/new_file
• > /tmp/new_file ( bash shell only )

touch is a standalone utility. Its original purpose is to update the access and modification time of a file, however if the file does not exist - it will be created. Note also that a filename - is treated specially, so if you do want to create a file that is named literally -, you'll have to enclose that into single or double quotes.

By contrast, > is a shell redirection operator for stdout stream. The > operator specifically calls the openat() system call with O_WRONLY|O_CREAT|O_TRUNC flags. That means, if the filename does not exist - it will be created, and if it does - the data will be truncated (and therefore gone, so > should be used with care). In most shells nowadays true or : is a built-in , so doing : > /tmp/new_file is going to be more efficient, although marginally compared to touch /tmp/new_file.

But of course it does not stop there. As mentioned, anything that can perform open(), openat() and, create() syscalls will create a file. Hence, we can do:

• true|dd of=/tmp/newfile
• truncate --size 0 /tmp/new_filename.txt
• cp /dev/null /tmp/null_file
• true|tee /tmp/some_other_file
• mktemp or tempfile ( for creating temporary files that do not need to exist between reboots !)

Of course, all the above mentioned utilities do not exclusively create files. But they perform the necessary syscall and that allows us to adapt the commands.

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Of course, at the level of programming or scripting we may want to create a file as well, especially for efficiency purposes (because calling external commands such as touch from a Perl script or Python will require additional resources).

Python one-liner:

$ python -c 'import sys,os;f=sys.argv[1];os.utime(f,None) if os.path.exists(f) else open(f,"a").close' myfile.txt

We can make it shorter with this:

$ python -c 'import sys,os;f=sys.argv[1];'$'\n''with open(f,"a"): os.utime(f,None)' mysecondfile.txt 

And in Perl:

$ perl -e 'open(my $fh,">","/tmp/perlfile")'

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¹ Other types of files such as hard/soft links,character or block special devices, directory,named pipes, or sockets require entirely different syscalls.