ACC SHELL

emulate [ -LR ] [ {zsh|sh|ksh|csh} [ -c arg ] ]
       Without any argument print current emulation mode.

       With single argument 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 `Compatibil-
       ity' in zshmisc(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 environ-
       ment; 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 emulate command and any
       setopt and trap commands to be local  to  the  immediately  sur-
       rounding  shell  function,  if  any;  normally these options are
       turned off in all emulation modes except ksh. The -L and -c  are
       mutually exclusive.

       If  -c  arg is given, evaluate arg while the requested emulation
       is temporarily in effect.  The emulation and all options will be
       restored  to  their original values before emulate returns.  The
       -R flag may be used.

       Use of -c enables `sticky' emulation mode for functions  defined
       within   the   evaluated  expression:   the  emulation  mode  is
       associated thereafter with the function  so  that  whenever  the
       function  is  executed the emulation (respecting the -R flag, if
       present) and all options are set before entry to  the  function,
       and  restored  after  exit.   If the function is called when the
       sticky emulation is already in effect, either within an `emulate
       shell  -c'  expression  or within another function with the same
       sticky emulation, entry and exit from the function do not  cause
       options to be altered (except due to standard processing such as
       the LOCAL_OPTIONS option).

       For example:

              emulate sh -c 'fni() { setopt cshnullglob; }
              fno() { fni; }'
              fno

       The two functions fni and fno are defined with sticky sh  emula-
       tion.   fno  is  then  executed, causing options associated with
       emulations to be set to their values in sh.  fni then calls fno;
       because  fno  is  also marked for sticky sh emulation, no option
       changes take place on entry to  or  exit  from  it.   Hence  the
       option  cshnullglob,  turned off by sh emulation, will be turned
       on within fni and remain on on return to fno.  On exit from fno,
       the emulation mode and all options will be restored to the state
       they were in before entry to the temporary emulation.

       The documentation above is typically sufficient for the intended
       purpose  of  executing code designed for other shells in a suit-
       able environment.  More detailed rules follow.
       1.     The sticky emulation  environment  provided  by  `emulate
              shell  -c'  is  identical  to that provided by entry to a
              function marked for sticky emulation as a consequence  of
              being  defined  in such an environment.  Hence, for exam-
              ple, the sticky emulation is  inherited  by  subfunctions
              defined within functions with sticky emulation.
       2.     No change of options takes place on entry to or exit from
              functions that are not marked for sticky emulation, other
              than  those that would normally take place, even if those
              functions are called within sticky emulation.
       3.     No special handling is provided for functions marked  for
              autoload nor for functions present in wordcode created by
              the zcompile command.
       4.     The presence or absence of the -R flag to emulate  corre-
              sponds  to different sticky emulation modes, so for exam-
              ple `emulate sh -c', `emulate -R sh -c' and `emulate  csh
              -c' are treated as three distinct sticky emulations.