How to show zsh function definition (like bash "type myfunc")?

The zsh idiom is whence, the -f flag prints function definitions:

zsh$ whence -f foo
foo () {
    echo hello
}
zsh$

In zsh, type is defined as equivalent to whence -v, so you can continue to use type, but you'll need to use the -f argument:

zsh$ type -f foo
foo () {
    echo hello
}
zsh$

And, finally, in zsh which is defined as equivalent to whence -c - print results in csh-like format, so which foo will yield the same results.

man zshbuiltins for all of this.

I've always just used which for this.

tl;dr

declare -f foo  # works in zsh and bash

typeset -f foo  # works in zsh, bash, and ksh

If you don't mind or prefer including all command forms that exist for a given name in the output:^{Thanks, Raine Revere.}

type -af  # zsh only (works differently in bash and ksh)

type -f / whence -f / which are suboptimal in this case, because their purpose is to report the command form with the highest precedence that happens to be defined by that name - as opposed to specifically reporting on the operand as a function.

That said, in practice this means that only an alias of the same name takes precedence (and technically also a shell keyword, though naming functions for shell keywords is probably a bad idea anyway).

Note that zsh does expand aliases in scripts by default (as does ksh, but not bash), and even if you turn alias expansion off first, type -f / whence -f / which still report aliases first.

In zsh, the -f option only includes shell functions in the lookup in zsh, so - unless -a is also used to list all command forms - an alias by the given name would print as the only output.

In bash and ksh, type -f actually excludes functions from the lookup; whence doesn't exist in bash, and in ksh it doesn't print the function definition; which is not a builtin in ksh and bash, and the external utility by definition cannot print shell functions.

If you're not quite sure what you are looking for, you can type just

functions

and it will show you all the defined functions.

Note that there are sometimes a LOT of them, so you might want to pipe to a pager program:

functions | less

to undefine a function, use

unfunction functionname