Useful [TclX] command for getting and manipulating [UNIX] identifiers of various kinds, especially including process, user and group ids.

**Subcommands**
    :   '''id user''' ?''name''?
    :   '''id userid''' ?''uid''?
    :   '''id group''' ?''name''?
    :   '''id groupid''' ?''gid''?
    :   '''id convert''' ''type entity''
    :   '''id effective''' ''type''
    :   '''id host'''
    :   '''id process''' ?''options...''?

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%| [Category TclX] | [Category Command] |%
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