linux - Purpose of the LISTER shell variable

Question

I'm trying to find what exactly a LISTER shell variable is used for. I'm doubting that it is for listing all the environmental variables but couldn't able to use it and also couldn't find it using man LISTER .

Answer 1

The LISTER environment variable is used by the mailx command to list folders. The default value is simply ls .

Documentation from the Single Unix Specification

LISTER

Determine a string representing the command for writing the contents of the folder directory to standard output when the folders command is given (see folders in Commands in mailx). Any string acceptable as a command_string operand to the sh -c command shall be valid. If this variable is null or not set, the output command shall be ls. The effects of this variable are unspecified if the User Portability Utilities option is not supported.