Deleting zero byte files

In the past I have shown ways to run Linux scripts on windows based system. I have also talked about one use of the find command, in conjunction with grep command to search for files having a given text content (say a word) in multiple folders.

Today I will show you another use of the find command: to automate tasks such as deleting zero byte files. This is a pretty common cleanup task that’s carried out on machines that are involved in EDI file transfers.

Here is the script:

find . -size 0 | sed -e 's/^/rm /' | sh

It deletes all zero byte files in the current folder, and in the folders below it.

In order to understand this, you may need to read about pipes. The task is carried out in three steps:

  1. find . -size 0 searches for all zero byte files in the given folder and the folders below it and returns the filepaths.
  2. sed -e 's/^/rm /' turns the list of names into a script – for example if the name is ‘/data/x’ it changes it to ‘rm /data/x’. More on sed here.
  3. the last steps simply forwards the script to the Linux shell for execution.

This is also a very flexible script and can be customised to carry out a wide variety of tasks. Please post your variations as comments.


Searching files within multiple folders

How to search file contents for a specific phrase using grep within multiple folders. Shows ways for both Linux and Windows.

On Linux, the normal way to search for some text within a file is to use grep (Global Regular Expression Print). However, grep has a limitation: it cannot automatically search folders within the current folder. It can only search within files in the current folder. Today I will show you how to use grep to search within all files and folders inside a current folder (recursively).

Windows users – despair not. If you find the standard windows search brain-dead or want to automate the task through scripts, you can also use this script. I have already explained various ways to run Linux scripts on windows – use the one that suits you.

We will couple grep with the find command, to unleash the power.

Here is what you need to do on Linux (or Cygwin):

find . -type f -exec grep -iH 'dedicated' {} \;

and use this for UnxUtils on Windows:

find . -type f -exec grep -iH "dedicated" \"{}\" ;

This does a case insensitive search for the word ‘dedicated’ in the current folder and all subfolders under it. Change -iH to -H for case sensitive search.

You can read the manuals for find and grep and change the commands to suit your needs – this method provides a lot of flexibility. Post your precise usage in comments, especially for Windows.