Get an environment variable with an optional default

Summary

The env macro looks up an environment variable and returns its value, or returns a default value if the variable is not set. The default is an empty string if not specified.

Syntax 

${env;<variable>[;<default>]}

Parameters

  • variable - The environment variable name to look up
  • default (optional) - Value to return if variable not set (default: empty string)

Behavior

  • Looks up environment variable via System.getenv()
  • Returns variable value if set
  • Returns default if variable not set
  • Default is empty string if not specified
  • Case-sensitive on Unix/Linux, case-insensitive on Windows

Examples

Get environment variable with default:

${env;JAVA_HOME;/usr/lib/jvm/default}

Check if variable exists:

${if;${env;CI};running-in-ci;local-build}

Use in paths:

user.home=${env;HOME;/home/default}

Empty default:

${env;OPTIONAL_VAR}
# Returns value or "" if not set

Use Cases

  • Accessing environment configuration
  • CI/CD environment detection
  • User-specific paths
  • System configuration
  • Platform differences
  • Secure credentials (with caution)

Notes

  • Accesses system environment variables
  • Case sensitivity varies by OS
  • Returns default for undefined variables
  • Empty string is valid default
  • Security: Be cautious with credentials
  • See also: ${def} for properties
  • See also: ${system} for system commands

See test cases in MacroTestsForDocsExamples.java