In this post I will take you through the useful lsof tool. If netcat was called the Swiss Army Knife of Network Connections, then I’d call lsof the Swiss Army Knife of Unix debugging.

Have you ever tried to unmount your USB thumb drive only to get the message "device is busy"? Like me, you probably thought, "I know I closed that file manager window. What's keeping it busy now?" fuser is a command that can answer that question for you, along with similar questions about what processes are using what files or sockets.

I use it most for getting network connection related information from a system, but that's just the beginning for this amazing and little-known application.

There are many ways to view files in GNU/Linux. One of the simplest command line tools for viewing files is cat. The cat command, short for concatenate, is actually intended for joining multiple files into one, but it works equally well for viewing text files.

Reading files is no big deal with bash: you just redirect the input to the script or pipe the output of another command into the script, or you could do it inside the script if the file names are pre-determined. You could also use process substitution to pass in the open files (command pipelines actually) from the command line.

I’ve already shown you how to view files with the cat command. In today’s post I’m going to show you how to use the GNU cat command for its originally intended purpose: for joining multiple files together.

An update to my previous article My vi first steps

I use vi instead of command line editors to do mass replacing of blocks and editing many files in the following way:

say I know all files I need to edit in the current directory contain the text foo and the rest of the files don't.

I open all files containing foo in vi:

In today's post I'm going to show how to use the command line find program to search for files. There are certainly different GUI tools available in Linux, such as Beagle, to search for files. The advantage of many of these systems is that they index the files on your system so that the searching is rather fast.

fdupes is a simple Command Line utility to find and list duplicate files in the specified directories. fdupes can also delete the found duplicate files if instructed. fdupes can follow Symlinks and can be instructed to ignore hardlinks. fdupes can also show the size of the duplicate files. fdupes is a simple and very efficient tool, easy to use.