Ssh X11 forwarding messes up with default shell

Question

I have a bash specific code in my bash profile:

$ cat ~/.bash_profile
#!/usr/bin/env bash

echo "SHELL: $SHELL"
function printfiles() {
  while IFS='' read -r _file || [[ -n "$_file" ]]; do
    echo "file: ${_file}"
  done < <(ls)
} && export -f printfiles

The < <(FUNCTION) is bash specific syntax, unsupported by sh. When I log in to a remote machine with ssh:

$ ssh my.remote
[email protected]'s password: 
Last login: Fri Nov 17 11:27:39 2017 from yyy.yy.yy.yy
sourcing /home/me/.bash_profile
SHELL: /bin/bash

It works fine. Now I want to log in again but forwarding my X11:

$ ssh -X my.remote
[email protected]'s password: 
sh: printfiles: line 2: syntax error near unexpected token `<'
                                                              sh: printfiles: line 2: ` done < <(ls)'
                                                                                                     sh: error importing function definition for `printfiles'
               sh: printfiles: line 2: syntax error near unexpected token `<'
                                                                             sh: printfiles: line 2: ` done < <(ls)'
                                                                                                                    sh: error importing function definition for `printfiles'
                              sh: printfiles: line 2: syntax error near unexpected token `<'
                                                                                            sh: printfiles: line 2: ` done < <(ls)'
                                                                                                                                   sh: error importing function definition for `printfiles'
                                             sh: printfiles: line 2: syntax error near unexpected token `<'
                                                                                                           sh: printfiles: line 2: ` done < <(ls)'
    sh: error importing function definition for `printfiles'
                                                            Last login: Fri Nov 17 11:28:51 2017 from yyy.yy.yy.yy
sourcing /home/me/.bash_profile
SHELL: /bin/bash

I have no clue what is happening, it seems that when I do the X11 forwarding somehow the sh shell is used over bash. Why so, how to solve that?

Answer 1

If I see inconsistencies between -X and -x logins, I suspect:

1. Differences among .bash_profile/.profile and .bashrc - see excellent discussion at https://serverfault.com/a/261807/116193
2. Interaction of my local environment with the remote - I debug this by stripping out controlling the local environment, such as with env -i ssh ...

Also: generally, I like to use -x to troubleshoot many of these types of things. You may be able to configure the Shell on the server side to enable the trace (-x) on login.

If I think of others, I'll update.