Wildcards are characters that can be used as a substitute for any of a class of characters in a search. Suppose there are hundreds and thousands of files and we have to find only xml files then in such cases we can use wild cards.
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| Input: ls -l *.xml
Output: Lists all files with "xml" extension
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Some common wild cards are:-
*: zero or more characters?: single character[]: range of character^: beginning of the line$: end of the line
Suppose we want to create 20 different files with names file1.txt file2.txt …file20.txt
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| Input: touch file{1..20}.txt
Output: Creates 20 different files with names file1.txt, file2.txt upto file20.txt
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Removing all files with filenames file1..file20.txt
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| Input: rm file*.txt
Output: Removes all files with extension .txt that begins with string `file`.
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Suppose we have to list every files in which first character can be anything but must be followed by 123
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| Input: ls -l ?123
Output: Lists every file whose first character is followed by 123
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Suppose we have to list all files that starts with te and ends with t but has a random character in between
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| Input: ls -l te?t
Output: Lists every files that starst with te and ends with t with a random character in between
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Suppose we have to list all files that starts with either a or b or c followed by 123
Suppose we have to list all files that starts with either any alphabet followed by 123
Suppose we have to list all files that have a number in its filename
Suppose we have a file names called names that has a bunch of name it it and want to print every line that start with R
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| #names
Leonard
Raj
Sheldon
Howard
Bernadette
Amy
Penny
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| Input: cat names | grep ^R
Output: Raj
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Suppose we have a file names called names that has a bunch of name it it and want to print every line that ends with y```
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| #names
Leonard
Raj
Sheldon
Howard
Bernadette
Amy
Penny ```
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| Input: cat names | grep y$
Output: Raj
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