In the shell, you'll often find yourself working with collections of files. For example, you might have lots of text files, Python scripts, or GIFs.
Right now, I have a collection of many image files in one directory, some of which have .gif extensions and some of which have .png extensions. The former are animated GIFs used for these guides, and the latter are still screenshots saved as PNGs.
That's a lot of files. I've decided I want to put the GIFs in their own folder, but how to move them without typing all of those names?
Well, Bash supports a number of wildcards for working with files, including the basic * and ? just discussed. Let's try the mv command with a wildcard:
[email protected] ~/adafruit_guides $ ls | wc -l 160 [email protected] ~/adafruit_guides $ mkdir ../adafruit_guide_gifs [email protected] ~/adafruit_guides $ mv *.gif ../adafruit_guide_gifs [email protected] ~/adafruit_guides $ ls | wc -l 63 [email protected] ~/adafruit_guides $ ls ../adafruit_guide_gifs/ | wc -l 97 [email protected]errypi ~/adafruit_guides $
To break this down,
-
ls | wc -lpipes the result oflstowc, which is a command for counting words and lines. The-loption tells it to only return the number of lines. This just tells us the number of files in the current directory. -
mkdir ../adafruit_guide_gifsmakes a new directory one level up from the current working directory (remember that..is another way of saying "the parent of this directory"). - In
mv *.gif ../adfaruit_guide_gifs, the wildcard*.gifis expanded by Bash to a list of all the files ending in.gifin the current directory, and then the command is executed like normal. - We use
wc -lagain to show that we've moved 63 files toadafruit_guide_gifs.
Since filename expansion of this kind (also known as globbing) is built into Bash, it works with any command that takes a list of filenames.
