Transfer all environment variables from one shell to another automatically

Question

I want to transfer all environment variables of the one shell (in my case: kornshell) to another shell (in my case: the z-shell) automatically.

If possible, the transfer should be in the startup file of the zshell to aviod the use of additional scripts as I want to transfer it to other servers for the same purpose.

What I tried so far:

1. put $ export $(ksh -c env | tr '\n' ' ') in the .zshrc (Startupfile of the Zshell).

   This was not working because the command is executed as a child of the current shell (zsh) which consequently has the same environment variables as the zsh and NOT the environment of the kornshell.

2. in an extra script

   #!/usr/bin/ksh
   echo $(ksh -c env | tr '\n' ' ') # for testing if it works
   export $(ksh -c env | tr '\n' ' ')
   

   This doent's work either.

Any comments are highly appreciated.

Answer 1

export $(ksh -c env | tr '\n' ' ')

does not work for me because "env" returns text like:

key1=value1 value2
...

So the above command will expand $(ksh -c env | tr '\n' ' ') and run:

export key1=value1 value2

But this generates error:

export: value2: is not an identifier

Note that there may be other bad characters on the right side of "=" sign in the output of "env", which will produce errors.

But there is a better way to export environment:

 export -p > myenv.sh

this outputs in Bash

 declare -x key1="value1 value2"
 ....

It appears that Bash "declare -x" is the same as "export". But in ksh "export -p" prints

export key1='value1 value2'
...

Now I just need to run

source myenv.sh 

to export all variables

But I also need to delete all existing variables before exporting new. I found solution at: http://www.linuxquestions.org/questions/linux-newbie-8/how-to-unset-environment-variable-in-bash-383066/

So, my final code is:

unset `env | awk -F= '/^\w/ {print $1}' | xargs`
source myenv.sh