How is realpath different from readlink?

readlink resolves only the immediate symbolic link. realpath goes further by resolving all symbolic links and directory components (like '..' and '.') in a path, providing the final, absolute, and unambiguous path.

When should I use realpath?

Use realpath when you need the definitive, absolute path to a file or directory, especially in scripts where paths might involve symbolic links or relative components, ensuring consistent and accurate referencing.

realpath Command

Q: What does the realpath command do in Linux?

The realpath command prints the canonicalized absolute pathname of a file or directory. This means it resolves all symbolic links, and processes all '.' and '..' components to give the true, absolute path.

The realpath command in Linux is used to print the canonicalized absolute pathname of a file or directory. This means it resolves all symbolic links (symlinks), and processes all . (current directory) and .. (parent directory) components in the path, providing the true, absolute, and unambiguous path to the target.

Syntax

realpath [OPTION]... FILE...

Description

realpath is particularly useful in scripting and automation where you need to ensure that you are operating on the actual file or directory, regardless of how it was referenced (e.g., through multiple layers of symbolic links or complex relative paths). It provides a clean, absolute path that can be reliably used by other commands or applications.

Common uses include:

Resolving symbolic links to their ultimate target.
Converting relative paths to absolute paths.
Normalizing paths by removing redundant . and .. components.
Verifying the existence of a file or directory (it returns an error if the path doesn't exist).

Common Options

Option	Description
`-z, --zero`	End each output line with NUL, not newline.
`--no-symlinks`	Do not expand symbolic links.
`--strip, -s`	Strip all but the last component.

Examples

Get the canonical absolute path of a file

                        realpath my_symlink.txt
                        
                        # If my_symlink.txt -> /home/user/documents/actual_file.txt
                        # Output: /home/user/documents/actual_file.txt

Resolves a symbolic link to its actual file path.

Resolve a relative path to an absolute path

                        cd /usr/local/bin

                        realpath ../../etc/passwd
                        
                        # Output: /etc/passwd

Converts a relative path containing .. components to its absolute form.

Normalize a path with redundant components

                        realpath ./my_dir/./another_dir/../file.txt
                        
                        # Output: /current/working/dir/my_dir/file.txt

Cleans up a path by resolving . and .. entries.

Use in a script to get a definitive path

                        #!/bin/bash

                        CONFIG_FILE="./config/app.conf"

                        ABSOLUTE_CONFIG=$(realpath "$CONFIG_FILE")

                        echo "Absolute config path: $ABSOLUTE_CONFIG"

Ensures that ABSOLUTE_CONFIG always holds the true, absolute path.