realpath — Resolve Absolute Canonical Paths

realpath converts any given path into its absolute canonical path.

It resolves:

• Relative paths (. and ..)
• Symbolic links
• Redundant slashes
• Nested references

The result is a fully expanded, unambiguous absolute path.

This makes it critical in production scripts, deployments, and WordPress VPS environments where symlinks (like current → releases/...) are common.

1. Core Purpose

Given:

./wp-content/../wp-config.php

realpath returns:

/var/www/html/wp-config.php

It removes ambiguity and normalizes the path.

2. Installation

realpath is part of GNU coreutils and is installed by default.

Verify:

realpath --version

3. Core Syntax

realpath [OPTION]... FILE...

• Accepts one or multiple paths
• Returns resolved absolute paths
• Works purely at filesystem level (unlike dirname/basename which are string-based)

4. Available Options

Option	Purpose
--	-
-e, --canonicalize-existing	Require all path components to exist
-m, --canonicalize-missing	Allow missing components
-s, --strip, --no-symlinks	Do not resolve symlinks
-L, --logical	Resolve logically (default)
-P, --physical	Resolve physically
--relative-to=DIR	Output path relative to DIR
--relative-base=DIR	Relative if under base, else absolute
-q, --quiet	Suppress errors
--help	Show help
--version	Show version

5. Practical Examples (WordPress VPS Context)

Assume WordPress root:

/var/www/html

Resolve Relative Path

realpath ./index.php

Output:

/var/www/html/index.php

Use case: Confirm exact location before editing.

Resolve Directory

realpath wp-content/themes

Output:

/var/www/html/wp-content/themes

Useful in deployment scripts.

Resolve Deployment Symlink

realpath current

Output:

/var/www/html/releases/release-2025-10

Confirms active release target.

Require Existing Path (-e)

realpath -e /etc/nginx/sites-enabled/wordpress.conf

Output:

/etc/nginx/sites-available/wordpress.conf

Fails if any component is missing.

Allow Missing Path (-m)

realpath -m /tmp/missing/file.txt

Output:

/tmp/missing/file.txt

Useful when preparing new file paths.

Do Not Resolve Symlink (-s)

realpath -s current

Output:

/var/www/html/current

Keeps symlink name intact.

Normalize ..

realpath /var/www/html/../html/wp-config.php

Output:

/var/www/html/wp-config.php

Removes redundant parent references.

Relative Output

realpath --relative-to=/var/www/html /var/www/html/wp-content/uploads

Output:

wp-content/uploads

Useful for generating config-relative paths.

Relative Base

realpath --relative-base=/var/www/html /etc/nginx/nginx.conf

Output:

/etc/nginx/nginx.conf

Falls back to absolute because path is outside base.

Multiple Files

realpath index.php wp-config.php

Output:

/var/www/html/index.php
/var/www/html/wp-config.php

Resolve multiple entries at once.

Quiet Mode

realpath -q missing.file

Output:

(no output)

Prevents noisy errors in scripts.

Mounted Uploads Storage

realpath wp-content/uploads

Output:

/mnt/storage/wp-uploads

Confirms external storage mount.

Compare Logical vs Physical

realpath -L current
realpath -P current

Usually same output unless nested symlinks exist.

Logical: follows symlink as seen Physical: resolves physical disk layout

Audit Symlinks

find -L /var/www/html -type l -exec realpath {} \;

Resolves all symlink targets.

Normalize Path in Script

FILE=../wp-config.php
ABS=$(realpath "$FILE")
echo "$ABS"

Ensures automation uses absolute path.

6. realpath vs readlink

Feature	realpath	readlink
-	-
Resolves relative paths	Yes	No
Resolves symlinks	Yes	Yes (with -f)
Normalizes ..	Yes	Only with -f
Canonical absolute output	Always	Only with -f
Allows missing paths	Yes (-m)	No

General rule:

• Use realpath for canonical normalization.
• Use readlink when you specifically need raw symlink targets.

7. WordPress VPS Use Cases

• Resolve current symlink during deployments
• Verify uploads mount path
• Normalize paths in cron jobs
• Ensure backup scripts use absolute paths
• Confirm Nginx/Apache symlink targets
• Audit storage mounts

8. Common Mistakes

Using -e on Missing File

realpath -e newfile.txt

Fails because file does not exist.

Use:

realpath -m newfile.txt

Expecting String-Only Behavior

Unlike dirname and basename, realpath interacts with filesystem.

Confusing -s

-s keeps symlink unresolved.

Remove it if you want actual target path.

9. Best Practices

• Use realpath -e in production scripts for safety.
• Use -m when preparing future file paths.
• Prefer absolute paths in automation.
• Combine with dirname and basename for full path manipulation.
• Use --relative-to in configuration generation.

10. Cheat Sheet

realpath file.txt
realpath -e file.txt
realpath -m /tmp/new/file.txt
realpath -s symlink
realpath --relative-to=/var/www/html path
realpath --relative-base=/var/www/html path
realpath -q missing.file

11. Mini Quiz

1. What does realpath guarantee in its output?
2. Which option allows missing paths?
3. What does -s change?
4. How do you output a relative path?
5. Why is realpath safer than using relative paths in automation?

Summary

realpath is essential for:

• Canonical path resolution
• Deployment safety
• Symlink validation
• Reliable automation scripts

In WordPress VPS environments with release symlinks, mounted uploads, and backup directories, realpath ensures every script operates on the exact intended location.