emulate

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.

Option	Description
`-R`	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.
`-L`	The options `LOCAL_OPTIONS` will be set, causing the effects of the emulate 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`.