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# Ruby Environment Variables

Ruby interpreter uses the following environment variables to control its behavior. The ENV object contains a list of all the current environment variables set.

Variable | Description
--- | ---
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.
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.

For Unix use env command to see a list of all environment variables.

    HOSTNAME=ip-72-167-112-17.ip.secureserver.net
    RUBYPATH=/usr/bin
    SHELL=/bin/bash
    TERM=xterm
    HISTSIZE=1000
    SSH_CLIENT=122.169.131.179 1742 22
    SSH_TTY=/dev/pts/1
    USER=amrood
    JRE_HOME=/usr/java/jdk/jre
    J2RE_HOME=/usr/java/jdk/jre
    PATH=/usr/local/bin:/bin:/usr/bin:/home/guest/bin
    MAIL=/var/spool/mail/guest
    PWD=/home/amrood
    INPUTRC=/etc/inputrc
    JAVA_HOME=/usr/java/jdk
    LANG=C
    HOME=/root
    SHLVL=2
    JDK_HOME=/usr/java/jdk
    LOGDIR=/usr/log/ruby
    LOGNAME=amrood
    SSH_CONNECTION=122.169.131.179 1742 72.167.112.17 22
    LESSOPEN=|/usr/bin/lesspipe.sh %s
    RUBYLIB=/usr/lib/ruby
    G_BROKEN_FILENAMES=1
    _=/bin/env

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