How to get the last dirname/filename in a file path argument in Bash?

Working with file paths is a common task in Bash scripting, and extracting the last component (filename) or parent directory name from a path is frequently needed. Bash provides several utilities to manipulate file paths effectively, with basename and dirname being the most commonly used commands.

Getting the Last Filename with basename

The basename command extracts the final component from a file path, removing all preceding directory components. This is useful when you need just the filename from a complete path.

Basic Usage

basename /path/to/file.txt

file.txt

Working with Environment Variables

You can use basename with environment variables like $PATH. Since $PATH contains multiple directories separated by colons, basename will return the last directory name.

echo $PATH

/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/go/bin:/Library/Apple/usr/bin:/Users/immukul/.cargo/bin

basename $PATH

bin

Getting Parent Directory Names with dirname

The dirname command returns the directory path by removing the last component. When combined with basename, you can extract directory names at different levels.

Getting the Second-to-Last Component

echo $(basename $(dirname $PATH))

.cargo

Getting the Third-to-Last Component

echo $(basename $(dirname $(dirname $PATH)))

immukul

Alternative Methods

Bash also provides parameter expansion methods for path manipulation without external commands:

# Get basename using parameter expansion
path="/home/user/documents/file.txt"
echo ${path##*/}

# Get dirname using parameter expansion
echo ${path%/*}

file.txt
/home/user/documents

Common Use Cases

Conclusion

The basename and dirname commands are essential tools for path manipulation in Bash. basename extracts the final component from a path, while dirname returns the parent directory. Combining these commands allows you to navigate and extract components at any level of a file path hierarchy.