How do I edit current shell command without executing it?

Question

There seems to be quite a lot of information on how to edit and execute a command using your editor using "edit-and-execute-command (C-x C-e)", but what I would like to achieve is take the current shell command, apply certain filtering (using a script) and then return it to prompt for further approval/manual changes before execution. Is this possible with bash?

Answer 1

Latest update based on my experience

The part 0"+y$dd in the following mapping is really something that you should carefully think about and tailor it to your taste/workflow/experience.

For instance, very frequently I've found myself ending up with multiple lines in the buffer, where I only want to execute the one the cursor is on; in this case I can use 0"+y$dd:%d<CR> instead of 0"+y$dd.

And this is just one of the possible scenarios.

Final answer for those who like vim

• Set vim as your EDITOR/VISUAL, so that when editing a command line, you will use vim to edit it.
• Put au BufEnter /tmp/bash-fc.* nn <Leader>d 0"+y$dd:wq<CR> in your ~/.vimrc file to map Leaderd (which you will rarely use when editing a command) to the action "delete the current line into the + register without the trailing EOL".
  • you can use either the + or the * register in the mapping above; the ways to paste into the terminal will likely differ; you need the +clipboard option for these registers to be available.
• When finished editing a command in the vim editor, hit EscapeLeaderd.
• Paste the clipboard into the terminal (this is terminal-dependent).

Original answer

I often need to do the same, and I do it as follows. (I normally use the set -o vi in bash, so points 1 and 2 in the following are different if you use set -o emacs, the default; based on your question it looks like points 1 and 2 are unified in Ctrl+x followed by Ctrl+e, which is harder to type, imho.)

1. hit Escape to be in normal mode,
2. hit v to enter the editor to edit the command,
3. edit the command as I like,

(This is where you ask the question.)

4. hit Escape0"+y$dd:wq,
   • Note: 0"+y$, not simply "+yy, as the latter would copy the newline too, and this would result in executing the command upon pasting it in the command line,
5. paste the clipboard on the command line
   • how to do this depends on the terminal you are using, I guess; I hit Ctrl+Alt+v in URxvt.
6. proceed to approval/manual edit.

Clearly this is just a workaround, consisting in copying the edited command into the clipboard before deleting the whole command, so that nothing gets executed upon exiting the editor; however it's the best I can get for myself.

Update

As my EDITOR (and VISUAL) is equal to vim, when I edit the command, I edit it in vim.

In this respect, I have noticed that the buffer is named /tmp/bash-fc.random, where random is a 6-characters alphanumeric random string.

This gives space to a lot of possiblities, if you use vim as your editor, as you can define some mapping in your .vimrc to execute the whole sequence Escape0"+y$dd:wq. For instance, one command that you'd rarely use when editing a command line is Leaderd; therefore you can put the following mapping in your .vimrc file

au BufEnter /tmp/bash-fc.* nn <Leader>d 0"+y$dd:wq<CR>

so that step 4 in the above recipe becomes

4. hit EscapeLeaderd