rm – How to Remove Files and Subdirectories of a Particular Folder

Yes, rm *.xvg will only delete the files with the specified extension in your current directory.

A good way to make sure you are indeed in the directory you want delete your files is to use the pwd command which will display your current directory and then do an ls to verify you find the files you are expecting.

If you are bit apprehensive about issuing the rm command, there are 2 things you can do:

1. type ls *.xvg to see a list of what files would be affected by this command.

2. Unless you have a lot of files, you could always also use the -i command line switch for rm (also exists for cp and mv). Using rm -i *.xvg would prompt you for each individual file if it was ok to delete it, so you could be sure nothing you didn't expect was getting deleted. (This will be tedious if you have a lot of files though :)

du, like any command that traverses directory trees recursively, operates in the following way:

1. Read information about a file, accessed via its path¹. In the case of du, the system call stat provides the file type (in particular, whether it's a directory) and size. Initially, the names are taken from the command line.
2. If the file is a directory, open it and read the list of file names.
3. For each file name in the directory, construct a file path (DIRECTORY/ENTRY_NAME) and act on it recursively starting at step 1. This step may be performed partly in parallel with the previous one (it depends on the implementation).

rm is running and deleting files one by one. Occasionally, du reads a file name in step 2, but by the time it gets around to processing it in step 3, rm has deleted it. Whether you see this error at all and how many times depends on the relative speed of rm and du and is pretty much unpredictable.

¹ There are only two ways to directly access a file: by path (including directory information, relative or absolute), or (if the file is open) by descriptor.