vim display message on execution of mapping

Question

I have mapped a key shortcut to copy all lines to system clipboard, which is working fine

 nnoremap <localleader>o :silent %w !pbcopy<cr>

I would like to display the message as 'Copied' in the status bar. Reading other answers, I found echom or echo can be used to display the messages

I have tried below

 nnoremap <localleader>o :silent %w !pbcopy<cr>|:echom "Copied"
 nnoremap <localleader>o :silent %w !pbcopy<cr>|echom "Copied"

These lines are placed in .vimrc. It appears lines are getting copied to clipboard, but the message is not being displayed anywhere.

1) How do I display the message from mapped command?

2) On opening a file, I see the 'Copied' message, and a line that says 'Press Enter to continue'. It appears the mapping is being invoked on sourcing the vimrc. The message should not be echoed while sourcing the vimrc file. How do I stop this?

Answer 1

From :help :!:

A '|' in {cmd} is passed to the shell, you cannot use
it to append a Vim command.  See :bar.

An alternative would be to use the system() function, like so:

:call system('pbcopy', getline(1, '$'))

The second argument is the stdin; in this case all all lines (like the % range).

In a mapping, it might look like:

nnoremap <localleader>o :silent :call system('pbcopy', getline(1, '$')) \| :echom 'Copied'<CR>

Notice that I used \| here, since otherwise Vim will see use the | to seperate echom from nnoremap, which isn't what we want. See :help map-bar

Vim stores the command's exit code in v:shell_error, so you can improve a bit on always showing "copied" by checking the value of that; for example:

:nnoremap <localleader>o :silent :call system('pbcopy', getline(1, '$'))
          \ \| :echom (v:shell_error > 0 ? ('Error: ' . v:shell_error) : 'Copied')<CR>

You can also display the pbcopy output on error instead of just the status code, but that's left as an exercise for the reader ;-)