Environment Variables

In addition to using arguments and options on the command line, the Ruby interpreter uses the following environment variables to control its behavior. The ENV object contains a list of current environment variables.

DLN_LIBRARY_PATH

Search path for dynamically loaded modules.

HOME

Directory moved to when no argument is passed to Dir::chdir. Also used by File::expand_path to expand “~”.

LOGDIR

Directory moved to when no arguments are passed to Dir::chdir and environment variable HOME isn’t set.

PATH

Search path for executing subprocesses and searching for Ruby programs with the -S option. Separate each path with a colon (semicolon in DOS and Windows).

RUBYLIB

Search path for libraries. Separate each path with a colon (semicolon in DOS and Windows).

RUBYLIB_PREFIX

Used to modify the RUBYLIB search path by replacing prefix of library path1 with path2 using the format path1;path2 or path1path2. For example, if RUBYLIB is: 

 /usr/local/lib/ruby/site_ruby

and RUBYLIB_PREFIX is:

 /usr/local/lib/ruby;f:/ruby

Ruby searches f:/ruby/site_ruby. Works only with DOS, Windows, and OS/2 versions.

RUBYOPT

Command-line options passed to Ruby interpreter. Ignored in taint mode (where $SAFE is greater than 0).

RUBYPATH

With -S option, search path for Ruby programs. Takes precedence over PATH. Ignored in taint mode (where $SAFE is greater than 0).

RUBYSHELL

Specifies shell for spawned processes. If not set, SHELL or COMSPEC are checked.

Get Ruby in a Nutshell now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial