| The environment (see environ(7)) is a list of name-value pairs that is passed to an executed program in the same way as a normal argument list. The names must be identifiers and the values are character strings. The shell interacts with the environment in several ways. On invocation, the shell scans the environment and creates a variable for each name found, giving it the corresponding value and attributes and marking it export. Executed commands inherit the environment. If the user modifies the values of these variables or creates new ones, using the export or typeset-x commands, they become part of the environment. The environment seen by any executed command is thus composed of any name-value pairs originally inherited by the shell, whose values may be modified by the current shell, plus any additions which must be noted in export or typeset-x commands. The environment for any simple-command or function may be augmented by prefixing it with one or more variable assignments. A variable assignment argument is a word of the form identifier=value. Thus: TERM=450 cmd args and (export TERM; TERM=450; cmd args) are equivalent (as far as the above execution of cmd is concerned except for special built-in commands listed below - those that are preceded with a dagger). If the obsolete -k option is set, all variable assignment arguments are placed in the environment, even if they occur after the command name. The following first prints a=b c and then c:
echo a=b c
set -k
echo a=b c
This feature is intended for use with scripts written for early versions of the shell and its use in new scripts is strongly discouraged. It is likely to disappear someday. | 
