CloneEnvironmentVariable returns a clone of the environment variable.

ExpandEnvironmentVariable returns a clone of envVarToExpand but with an expanded value based on environment variables defined in envvars list.

ExpandEnvironmentVariables returns a list of environment variables with their value being expanded.

FindEnvironmentVariable looks for an environment variable in a list.

FindFoldEnvironmentVariable looks for an environment variable in a list similarly to FindEnvironmentVariable but without case-sensitivity.

MergeEnvironmentVariableSets merges two sets of environment variables.

NewCurrentEnvironment returns system current environment.

NewEnvironmentVariable returns an environment variable defined by a key and a value.

NewEnvironmentVariableWithValidation returns an environment variable defined by a key and a value but with the possibility to define value validation rules.

ParseEnvironmentVariable parses an environment variable definition, in the form "key=value".

ParseEnvironmentVariables parses a list of key=value entries such as os.Environ() and returns a list of the corresponding environment variables.

SortEnvironmentVariables sorts a list of environment variable alphabetically no matter the case.

UniqueEnvironmentVariables returns a list of unique environment variables.

ValidateEnvironmentVariables validates that environment variables are correctly defined in regard to their schema.

IsEnvironmentVariableKey defines a validation rule for environment variable keys ([IEEE Std 1003.1-2008 / IEEE POSIX P1003.2/ISO 9945.2](http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_10_02)) for use with github.com/go-ozzo/ozzo-validation TODO use the built-in implementation in `is` package when https://github.com/go-ozzo/ozzo-validation/issues/186 is looked at.

IEnvironment defines an environment for an application to run on.

IEnvironmentVariable defines an environment variable to be set for the commands to run.