CompTIA Linux+ XK0-005 - 3.1 - Shell Script Elements - Parameter Expansion: Globbing

Globbing is a powerful feature in shell scripting that allows you to match filenames or paths based on patterns called globs. Globs are special characters or sequences of characters that represent sets of filenames or paths. Understanding globbing is crucial for effective file manipulation and management in shell scripts.

Using Globs

Globs are used to match filenames or paths based on specific patterns. Here are some common glob characters and their meanings:

*: Matches any sequence of characters (including an empty sequence).
?: Matches any single character.
[characters]: Matches any single character that is a member of the specified characters. [bdfhjln]
[!characters]: Matches any single character that is not a member of the specified characters. [!acegikm]
[a-z]: Matches any single character from a to z.
[0-9]: Matches any single digit from 0 to 9.
**: Matches any files and zero or more directories and subdirectories.

By incorporating globs into your shell scripts, you can perform operations on multiple files or directories at once. For example, you can use globs with commands like cp, mv, rm, or ls to select specific files or directories based on patterns.

Examples of Globs

Here are some examples of using globs in shell scripts:

Matching files with a specific extension:

# List all files with a .txt extension
ls *.txt

Matching files with a specific prefix:

# Copy all files starting with "prefix" to a destination directory
cp prefix* /path/to/destination/

Matching files using character ranges:

# List all files with names starting with a lowercase letter
ls [a-z]*

Matching files with multiple patterns:

# Remove all files with either a .tmp or .bak extension
rm *.tmp *.bak

Experiment with different glob patterns to gain a deeper understanding of how they work and how they can be used to manipulate and manage files and directories in your shell scripts.

Conclusion

Globbing is a powerful mechanism in shell scripting that allows you to match filenames or paths based on patterns. By incorporating globs into your scripts, you can perform operations on multiple files or directories at once, simplifying tasks like file copying, moving, or deleting.

Take the time to practice using globs in various scenarios to become familiar with their capabilities. Understanding globbing will not only enhance your scripting skills but also help you tackle complex file management tasks efficiently.

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