Linux : Create dummy file of any size for test purpose using fallocate

Requirement :

Create dummy/fake file of desired size using Linux terminal

    There might be some test requirement to mimic the prod setup, in my case I have to write a script to validate files before downloading, instead of making request to prod site I just created a local setup and placed similar dummy files to replicate the prod environment.

Let's know the one linux one liner using tool fallocate to create dummy file of desired size.

• Fallocate is the Linux terminal utility.

One Liner

 
 #  fallocate -l <size_of_file> <desired_name_of_file>

• Fallocate is the Linux terminal utility.

Syntax Template

 #  fallocate -l 15M myfile.img

• <size_of_file >
• in GB and MB : M for MB and G for GB
• example : 15M for 15 MB and 5G for 5GB
• <desired_name_of_file> 
• It can be anything with our without extension : myfile.tar or myfile.img or myfile or anything

Using Linux for loop and Seq to generate a series of file.

Example : 

• Below one liner can be used to generate 100 files of 15mb each with suffix changes as file count number.

Syntax Template

 #  for val in `seq 100`; do fallocate -l 15M demo060621000$val.tar; done;

Output : File starts with name 

demo0606210001.tar and ends with demo0606210099.tar

Syntax Output

 #  ls -ltr

-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210001.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210002.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210003.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210004.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210005.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210006.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210007.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210008.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo0606210009.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100010.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100011.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100012.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100013.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100014.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100015.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100016.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100017.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100018.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100019.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100020.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100021.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100022.tar
-rw-r--r-- 1 root root 15728640 Jun  6 23:25 demo06062100023.tar