W3cubDocs

/Crystal 0.31

module ENV

Overview

ENV is a hash-like accessor for environment variables.

Example

# Set env var PORT to a default if not already set
ENV["PORT"] ||= "5000"
# Later use that env var.
puts ENV["PORT"].to_i

NOTE All keys and values are strings. You must take care to cast other types at runtime, e.g. integer port numbers.

Extended Modules

Defined in:

env.cr

Class Method Summary

Class Method Detail

def self.[](key : String) : StringSource

Retrieves the value for environment variable named key as a String. Raises KeyError if the named variable does not exist.

def self.[]=(key : String, value : String?)Source

Sets the value for environment variable named key as value. Overwrites existing environment variable if already present. Returns value if successful, otherwise raises an exception. If value is nil, the environment variable is deleted.

If key or value contains a null-byte an ArgumentError is raised.

def self.[]?(key : String) : String?Source

Retrieves the value for environment variable named key as a String?. Returns nil if the named variable does not exist.

def self.clearSource

def self.delete(key : String) : String?Source

Removes the environment variable named key. Returns the previous value if the environment variable existed, otherwise returns nil.

def self.each(&block)Source

Iterates over all KEY=VALUE pairs of environment variables, yielding both the key and value.

ENV.each do |key, value|
  puts "#{key} => #{value}"
end

def self.fetch(key, default)Source

Retrieves a value corresponding to the given key. Return the second argument's value if the key does not exist.

def self.fetch(key) : StringSource

Retrieves a value corresponding to the given key. Raises a KeyError exception if the key does not exist.

def self.fetch(key : String, &block : String -> String?)Source

Retrieves a value corresponding to a given key. Return the value of the block if the key does not exist.

def self.has_key?(key : String) : BoolSource

Returns true if the environment variable named key exists and false if it doesn't.

def self.inspect(io)Source

Writes the contents of the environment to io.

def self.keys : Array(String)Source

Returns an array of all the environment variable names.

def self.pretty_print(pp)Source

def self.values : Array(String)Source

Returns an array of all the environment variable values.

© 2012–2019 Manas Technology Solutions.
Licensed under the Apache License, Version 2.0.
https://crystal-lang.org/api/0.31.1/ENV.html