export function from zsh to bash for use in gnu parallel

Question

How do I export a function from zsh, so that I can use it in gnu parallel?

example:

function my_func(){ echo $1;}
export -f my_func
parallel "my_func {}" :::  1 2

in bash will output

1
2

whereas in zsh it will output error messages

/bin/bash: my_func: command not found
/bin/bash: my_func: command not found

Answer 1

A lot has changed since 2014.

Today you simply do:

# Activate env_parallel function (can be done in .zshenv)
. `which env_parallel.zsh`

function my_func(){ echo $1;}
env_parallel "my_func {}" :::  1 2

If your environment is big:

# Activate env_parallel function (can be done in .zshenv)
. `which env_parallel.zsh`

# Record which environment to ignore
env_parallel --session

function my_func(){ echo $1;}
env_parallel "my_func {}" :::  1 2

Answer 2

zsh does not have a concept of exporting functions. export -f somefunc will print the function definition, it will not export a function.

Instead, you can rely on the fact that bash functions are exported as regular variables starting with ():

export my_func='() { echo "$1"; }'
parallel --gnu "my_func {}" ::: 1 2 

Answer 3

Based on that other guy's answer. You can write a function that export a zsh function that already defined to bash

function exportf (){
    export $(echo $1)="`whence -f $1 | sed -e "s/$1 //" `"
}

Usage

function my_func(){
    echo $1;
    echo "hello";
}

exportf my_func
parallel "my_func {}" :::  1 2

Answer 4

This approach allows you to define a function in zsh (without worrying about adding a quote level). Also it does not require adding additional software.

Make a function. Here's one:

function bar {
    echo bar
    echo $1
}

And spin it up:

seq 10 | xargs -I{} -n1 -P1 zsh -c "$(whence -f bar); bar {}"

I'm using xargs at the minute but of course the same approach works for GNU Parallel, so thought I'd share it here.