An important concept to grasp in Linux is that of using wildcards. In a sporting context a wildcard is something (or someone) that can be introduced to a game as a substitute. It may not have a strictly defined value, but could fill in for a range of standard objects.
Wildcards are a feature on the Linux command line (and other places) that makes the command line far more versatile than graphical file managers. Anyone who’s tried to use fancy combinations of shift / ctrl and mouse clicking while sorting in a file manager will attest to a degree of difficulty.
For example, if we have a directory with a large number files and sub-directories, and we need to move all the Python (files ending in .py) files, that have the word ‘pi’ somewhere in their names, from that large directory into another directory. This has the potential to be a time consuming task.
At the Linux command line that task is almost as easy to carry out as moving only one Python file, and it’s simple because of the wildcards. These are special characters that allow us to select file names that match certain patterns of characters. This helps us select a range of matching of files by typing just a few characters, and in most cases (IMHO) it’s easier than using a graphical file manager.
Here’s a list of the most commonly used wildcards :
As well as being able to be applied in isolation, some of the real strengths of wildcards comes when using them in combination.
Zero or more characters
To list all Python files with ‘pi’ in their names;
Exactly one character
To list all files in the current directory with three character file extensions;
Exactly one of the characters listed
To list all files that have an extension that begins with ‘p’ or ‘j’;
Exactly one character in the range specified
To list all files that have a number in the file name;
To list all files that start with one of the three first or three last letters of the alphabet and end with an extension ‘jpg’ or ‘png’.
The post above (and heaps of other stuff) is in the book 'Just Enough Linux' that can be downloaded for free (or donate if you really want to :-)).