We always want to be as efficient as possible when working as a programmer. In the past I've shown how to run commands on singular files & directories. Let's look at how we can use wildcards to refer to multiple files/directories and make our lives easier.
Wildcards are symbols that allows to make paths that refer to multiple files and directories. Instead of a path that goes to only one file, you create a pattern. That pattern will refer to any file/folder that it applies to.
These are the fundamental wildcards:
*- represents zero or more characters?- represents a single character[]- represents a range of characters
Let's start with the * and see it in action below.
user@bash: pwd
/home/devin/tutorials
user@bash: ls
barry.txt blah.txt bob example.png firstfile foo1 foo2
foo3 frog.png secondfile thirdfile video.mpeg
user@bash: ls b*
barry.txt blah.txt bob
user@bash: Essentially what ls b* is doing is telling the terminal to find everything in the current directory, that starts with "b", and can have either nothing or anything after it.
That's pretty general though. What if I wanted to find all the files in my Documents folder ending in ".txt". I'd do something like this:
user@bash: ls /home/devin/Documents/*.txt
example1.txt example2.txtThe question mark stands in place of any single character. So if I wanted to find any file that had i as it's second letter in my Music folder I would do this:
user@bash: ls /home/devin/Music/?i*
big-song.mp3 video.mp4The brackets are a way for you to specify a range of characters. For example, if I wanted to find an image file in my current directory that started with a lowercase letter, then a single digit, and then ended with ".jpg" I would do this:
user@bash: ls [a-z][0-9]*.jpg
C4-explosion.jpgThat was pretty cool right? Now we don't have to just run ls on a whole directory and see everything. Sometimes we just wanna see a few files. In the next lesson we'll talk about permissions.