emulate [ -LR ] {zsh|sh|ksh|csh}
       Set  up  zsh  options  to emulate the specified shell as much as
       possible.  csh will never be fully emulated.  If the argument is
       not  one  of  the  shells  listed  above,  zsh will be used as a
       default; more precisely, the tests performed on the argument are
       the  same  as  those  used to determine the emulation at startup
       based on the shell name, see the section `Compatibility' in zsh-
       misc(1)  .   If the -R option is given, all options are reset to
       their default value corresponding  to  the  specified  emulation
       mode,  except  for  certain  options  describing the interactive
       environment; otherwise,  only  those  options  likely  to  cause
       portability  problems  in scripts and functions are altered.  If
       the  -L  option  is  given,  the   options   LOCAL OPTIONS   and
       LOCAL TRAPS will be set as well, causing the effects of the emu-
       late command and any setopt and trap commands to be local to the
       immediately  surrounding  shell function, if any; normally these
       options are turned off in all emulation modes except ksh.
