unset - unset an environment variable
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   unset [-h] <variables>

   A variable environment is maintained by the command interpreter. The "set"
   command sets a variable to a particular value, and the "unset" command
   removes the definition of a variable.

   Command options:

   -h
          Print the command usage.

   <variables>
          Variables to be unset
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   Last updated on 20100410 00h02