File Path Validation Regex (Linux/Unix)

Validate Linux/Unix file paths starting with forward slash and containing valid path characters using regex pattern.

Pattern Breakdown

^(\/[^/ ]*)+\/?$

Components

Detailed Breakdown

• (\/[^/ ]*)+ - Path segments (one or more):
  • \/ - Literal forward slash (path separator)
  • [^/ ]* - Zero or more characters that are not / or space
  • + - One or more segments
• \/? - Optional trailing slash for directories

Examples

Valid:

• /home/user/documents/file.txt
• /usr/bin/python
• /var/log/
• /etc/nginx/nginx.conf
• /
• /root/.bashrc

Invalid:

• home/user/documents/file.txt (missing leading slash)
• /home/user /documents/file.txt (contains space)
• /home/user//documents/file.txt (double slash)
• C:\Users\Documents\file.txt (Windows path)
• /home/user/documents/file.txt (trailing space)

Implementation

JavaScript

const unixPathRegex = /^(\/[^/ ]*)+\/?$/;
unixPathRegex.test('/home/user/documents/file.txt'); // true
unixPathRegex.test('/usr/bin/python'); // true
unixPathRegex.test('/var/log/'); // true
unixPathRegex.test('home/user/documents/file.txt'); // false (missing leading slash)
unixPathRegex.test('/home/user /documents/file.txt'); // false (contains space)

Python

import re
unix_path_regex = r'^(\/[^/ ]*)+\/?$'
bool(re.match(unix_path_regex, '/home/user/documents/file.txt'))  # True
bool(re.match(unix_path_regex, '/usr/bin/python'))  # True
bool(re.match(unix_path_regex, 'home/user/documents/file.txt'))  # False (missing leading slash)

Go

unixPathRegex := regexp.MustCompile(`^(\/[^/ ]*)+\/?$`)
unixPathRegex.MatchString("/home/user/documents/file.txt") // true
unixPathRegex.MatchString("/usr/bin/python") // true
unixPathRegex.MatchString("home/user/documents/file.txt") // false (missing leading slash)

Limitations

1. No relative paths: Only absolute paths starting with /
2. No spaces: Doesn't allow spaces in path segments
3. No special chars validation: Doesn't check for all invalid characters
4. No length limits: Doesn't enforce PATH_MAX limits
5. Format only: Validates format, not actual file existence
6. No hidden file validation: Doesn't specifically validate dot-files

When to Use

• Linux/Unix file path format validation
• File upload validation on Unix systems
• Path sanitization
• When you need to ensure valid Unix path format
• File system operations on Linux/Unix

For production, consider:

• Supporting relative paths if needed
• Allowing spaces (with proper escaping)
• Validating path length limits (PATH_MAX = 4096 on Linux)
• Checking for null bytes and other invalid characters
• Using OS-specific path validation libraries