Expand subshell before executing it?

Question

I often run commands using subshells, and sometimes would like to have the subshells expanded before I run something.. This way I could verify what I'm doing, and possibly edit what's about to happen as well.

For example, how can I get the following command line to be expanded before I run it, so I can edit the results of the subshell?

e.g.

$ find -name "test.txt" 
/tmp/test.txt

$ mv $(!!) /tmp/new.txt

I'd like to see the subshell expanded before I run the command, like so:

$ mv /tmp/test.txt /tmp/new.txt

Is there some way to do this?

Answer 1

shell-expand-line (\e\C-e) expands command substitutions in bash.

$ bind -p|grep shell-ex
"\e\C-e": shell-expand-line

$(!!)\e\C-e would run the previous command again and insert the output:

"\eo": "$(!!)\e\C-e"

It also expands other command substitutions, but there is no command like shell-expand-word.

In bash 4.0 or later you could also enable globstar, type **/file.txt, and use glob-complete-word (\eg) or glob-expand-word (\C-x*).

Answer 2

Here’s a handy trick — add this line to ~/.inputrc (creating the file if necessary):

Control-x: shell-expand-line

Note you could also either of the following to expand only history, or your aliases, or both:

Control-x: history-expand-line

or

Control-x: alias-expand-line

or

Control-x: history-and-alias-expand-line

This was gleaned from this blog, and this question on SuperUser, which is very similar: