In Unix-like operating systems, wildcards are special characters used to represent patterns in filenames or text strings. They are widely used in command-line interfaces (CLI) to perform operations such as file matching, searching, and manipulation. Wildcards allow users to specify a set of files or text strings that match a particular pattern, rather than explicitly specifying each individual item. Some common Unix wildcards include:
1. (asterisk) : Represents zero or more characters. It matches any sequence of characters in a filename or text string. For example:
* *.txt matches all files with a ".txt" extension.
* file* matches all files whose names start with "file".
2. ? (question mark) : Represents exactly one character. It matches any single character in a filename or text string. For example:
* file?.txt matches files like "file1.txt", "fileA.txt", etc.
3. [] (square brackets) : Represents a range of characters or a character class. It matches any single character within the specified range or class. For example:
* [abc] matches any one of the characters 'a', 'b', or 'c'.
* [0-9] matches any digit from 0 to 9.
* [!0-9] matches any character that is not a digit.
4. {} (curly braces) : Represents a list of comma-separated strings or a range of numbers. It matches any of the strings or numbers specified within the braces. For example:
* {file1,file2,file3}.txt matches "file1.txt", "file2.txt", and "file3.txt".
* {1..5} matches the numbers 1, 2, 3, 4, and 5.
Unix wildcards are commonly used with commands like
ls,
cp,
mv,
rm, and
grep to perform file operations, file matching, and text processing. They provide a powerful and flexible way to specify patterns and perform operations on multiple files or text strings at once, saving time and effort for users working in the command line.
