BitmapCake!

Last week I wrote an automation script, which (a part of it) generated some files, and I wanted to store them for a maximum of three days. So along with the script, I wrote another bash script to delete any files which are older than three days, and I set it to run as a cron job.

After writing all the scripts, I wanted to test whether they work. For tests, I needed some files which are at least three days old and useless at the same time because my script will be deleting them.

So how did I do that?

I believe you all know about the touch command. What does it actually do? Well, I'm sure most of us will say "we use it to create a file". It's true. But that's not what touch command does. Its real purpose is to change the access and modification time of a file. It will create a new file only if it doesn't exist ;) So this blog post is about how to do it. I thought of sharing it in my blog for my own reference as well as a help for those who will be looking for it in the future ;)

In the touch's manual page, it says:

Update  the  access  and modification times of each FILE to the current time.

A FILE argument that does not exist is created empty, unless -c  or  -h
is supplied.

A  FILE  argument  string of - is handled specially and causes touch to
change the times of the file associated with standard output.

Mandatory arguments to long options are  mandatory  for  short  options
too.

So, that's it. You just have to add the -d parameter and pass in a timestamp and it will create the file with given date / time. If the file already exists, it will modify the access / created time to the given one. Too easy right? For my specific requirement, the following command was enough for me.

touch -d '4 day ago' test.txt

As you can see, the value given to the -d parameter could be a human friendly syntax like shown above. You can also pass in a timestamp if you wish. Please read the manual page for more information on that.

I hope this will be helpful for someone :)