realpath

Overview

The realpath command prints the resolved absolute path by resolving symbolic links and relative path components like . and ...

Syntax

realpath [options] file...

Common Options

Option Description
-e All components must exist
-m No components need exist
-L Resolve symbolic links
-P Don’t resolve symbolic links
-q Suppress error messages
-s Don’t expand symbolic links
-z End output with NUL
--relative-to=dir Print relative path
--relative-base=dir Print absolute unless under base

Key Use Cases

  1. Resolve absolute paths
  2. Canonical path determination
  3. Symbolic link resolution
  4. Script portability
  5. Path normalization

Examples with Explanations

Example 1: Basic Usage

realpath ../file.txt

Returns absolute path of the file

Example 2: Relative Path

realpath --relative-to=/home/user /home/user/docs/file.txt

Returns: docs/file.txt

Example 3: Multiple Files

realpath *.txt

Returns absolute paths for all txt files

Common Usage Patterns

  1. Script location:

    SCRIPT_PATH=$(realpath "$0")
SCRIPT_DIR=$(dirname "$SCRIPT_PATH")

  2. Canonical comparison:

    if [ "$(realpath file1)" = "$(realpath file2)" ]; then
    echo "Same file"
fi

  3. Relative path calculation:

    realpath --relative-to="$PWD" /absolute/path

Best Practices

  1. Use for portable path handling
  2. Check if files exist when needed
  3. Handle symbolic links appropriately
  4. Consider relative vs absolute needs
  5. Quote paths with spaces

Integration Examples

  1. Config file resolution:

    CONFIG=$(realpath "${CONFIG_FILE:-./config.conf}")

  2. Backup path calculation:

    BACKUP_PATH=$(realpath "$HOME/../backups")