When tmux is started, it inspects the following environment
variables:
EDITOR If the command specified in this variable contains the
string 'vi' and VISUAL is unset, use vi-style key
bindings. Overridden by the mode-keys and status-keys
options.
HOME The user's login directory. If unset, the passwd(5)
database is consulted.
LC_CTYPE The character encoding locale(1). It is used for two
separate purposes. For output to the terminal, UTF-8 is
used if the -u option is given or if LC_CTYPE contains
"UTF-8" or "UTF8". Otherwise, only ASCII characters are
written and non-ASCII characters are replaced with
underscores ('_'). For input, tmux always runs with a
UTF-8 locale. If en_US.UTF-8 is provided by the
operating system it is used and LC_CTYPE is ignored for
input. Otherwise, LC_CTYPE tells tmux what the UTF-8
locale is called on the current system. If the locale
specified by LC_CTYPE is not available or is not a UTF-8
locale, tmux exits with an error message.
LC_TIME The date and time format locale(1). It is used for
locale-dependent strftime(3) format specifiers.
PWD The current working directory to be set in the global
environment. This may be useful if it contains symbolic
links. If the value of the variable does not match the
current working directory, the variable is ignored and
the result of getcwd(3) is used instead.
SHELL The absolute path to the default shell for new windows.
See the default-shell option for details.
TMUX_TMPDIR
The parent directory of the directory containing the
server sockets. See the -L option for details.
VISUAL If the command specified in this variable contains the
string 'vi', use vi-style key bindings. Overridden by
the mode-keys and status-keys options.
