Determine NLS_LANG on linux

How do I determine the NLS_LANG setting for my Oracle Client on linux?

I haven't set the NLS_LANG explicitly.

Is it necessary to set and export the variable NLS_LANG=AMERICAN_AMERICA.AL32UTF8 for applications delivering utf-8 encoded characters to the database?

Is the Oracle client already aware of the encoding based on my locale?

me@ora11gR2> !echo $LANGen_US.UTF-8me@ora11gR2> !localeLANG=en_US.UTF-8LC_CTYPE="en_US.UTF-8"LC_NUMERIC="en_US.UTF-8"LC_TIME="en_US.UTF-8"LC_COLLATE="en_US.UTF-8"LC_MONETARY="en_US.UTF-8"LC_MESSAGES="en_US.UTF-8"LC_PAPER="en_US.UTF-8"LC_NAME="en_US.UTF-8"LC_ADDRESS="en_US.UTF-8"LC_TELEPHONE="en_US.UTF-8"LC_MEASUREMENT="en_US.UTF-8"LC_IDENTIFICATION="en_US.UTF-8"LC_ALL=me@ora11gR2> !echo $NLS_LANGme@ora11gR2> @.[$NLS_LANG]SP2-0310: unable to open file ".[$NLS_LANG]"