1. As others have indicated, and as was explained in the page you link to, output messages to the echo area are logged in buffer *Messages*. Clicking in the echo area brings up *Messages*, where you can copy text normally.

2. In the minibuffer, which is for input (as opposed to the echo area, which is in the same place, and which is for output), if you use normal, vanilla Emacs then you can just copy (and yank) there normally. IOW, you can edit text in the minibuffer.

3. #2 is not true, however, if you use something like Ido mode. That co-opts the normal editing behavior of the minibuffer for its own purposes. Keys that would normally edit text in the minibuffer do not, when you are in Ido mode.

(FWIW, Icicles does not do this. It lets you edit minibuffer text normally, Even more so than vanilla Emacs, in fact, in that SPC, ?, and newline (C-j) characters self-insert normally. Of course, TAB and RET are not normal editing keys in the minibuffer.)

4. As @wvxwv mentioned in a comment to your question, the prompt area of the minibuffer is generally read-only text. But you can certainly copy it. Just back into it (e.g. using C-b or the left-arrow key) and copy text from the prompt normally (e.g., C-SPC move cursor with C-f, M-f, etc., followed by M-w).

   And then you can yank it anywhere, including in the minibuffer input area (after the prompt).

   (The prompt area is read-only, and some cursor movement keys will not move into it, simply for convenience. For example, C-a takes you to the beginning of your input area, not to the beginning of the line, which would be within the prompt area. This is the reason for mentioning C-b, as it is one way that you can move the cursor into the prompt area.)

1. As others have indicated, and as was explained in the page you link to, output messages to the echo area are logged in buffer *Messages*. Clicking in the echo area brings up *Messages*, where you can copy text normally.

2. In the minibuffer, which is for input (as opposed to the echo area, which is in the same place, and which is for output), if you use normal, vanilla Emacs then you can just copy (and yank) there normally. IOW, you can edit text in the minibuffer.

3. #2 is not true, however, if you use something like Ido mode. That co-opts the normal editing behavior of the minibuffer for its own purposes. Keys that would normally edit text in the minibuffer do not, when you are in Ido mode.

   (FWIW, Icicles does not do this. It lets you edit minibuffer text normally, Even more so than vanilla Emacs, in fact, in that SPC, ?, and newline (C-j) characters self-insert normally. Of course, TAB and RET are not normal editing keys in the minibuffer.)

4. As @wvxwv mentioned in a comment to your question, the prompt area of the minibuffer is generally read-only text. But you can certainly copy it. Just back into it (e.g. using C-b or the left-arrow key) and copy text from the prompt normally (e.g., C-SPC move cursor with C-f, M-f, etc., followed by M-w).

   And then you can yank it anywhere, including in the minibuffer input area (after the prompt).

   (The prompt area is read-only, and some cursor movement keys will not move into it, simply for convenience. For example, C-a takes you to the beginning of your input area, not to the beginning of the line, which would be within the prompt area. This is the reason for mentioning C-b, as it is one way that you can move the cursor into the prompt area.)

1. As others have indicated, and as was explained in the page you link to, output messages to the echo area are logged in buffer *Messages*. Clicking in the echo area brings up *Messages*, where you can copy text normally.

2. In the minibuffer, which is for input (as opposed to the echo area, which is in the same place, and which is for output), if you use normal, vanilla Emacs then you can just copy (and yank) there normally. IOW, you can edit text in the minibuffer.

3. #2 is not true, however, if you use something like Ido mode. That co-opts the normal editing behavior of the minibuffer for its own purposes. Keys that would normally edit text in the minibuffer do not, when you are in Ido mode.

(FWIW, Icicles does not do this. It lets you edit minibuffer text normally, Even more so than vanilla Emacs, in fact, in that SPC, ?, and newline (C-j) characters self-insert normally. Of course, TAB and RET are not normal editing keys in the minibuffer.)

1. As others have indicated, and as was explained in the page you link to, output messages to the echo area are logged in buffer *Messages*. Clicking in the echo area brings up *Messages*, where you can copy text normally.

2. In the minibuffer, which is for input (as opposed to the echo area, which is in the same place, and which is for output), if you use normal, vanilla Emacs then you can just copy (and yank) there normally. IOW, you can edit text in the minibuffer.

3. #2 is not true, however, if you use something like Ido mode. That co-opts the normal editing behavior of the minibuffer for its own purposes. Keys that would normally edit text in the minibuffer do not, when you are in Ido mode.

(FWIW, Icicles does not do this. It lets you edit minibuffer text normally, Even more so than vanilla Emacs, in fact, in that SPC, ?, and newline (C-j) characters self-insert normally. Of course, TAB and RET are not normal editing keys in the minibuffer.)

4. As @wvxwv mentioned in a comment to your question, the prompt area of the minibuffer is generally read-only text. But you can certainly copy it. Just back into it (e.g. using C-b or the left-arrow key) and copy text from the prompt normally (e.g., C-SPC move cursor with C-f, M-f, etc., followed by M-w).

   And then you can yank it anywhere, including in the minibuffer input area (after the prompt).

   (The prompt area is read-only, and some cursor movement keys will not move into it, simply for convenience. For example, C-a takes you to the beginning of your input area, not to the beginning of the line, which would be within the prompt area. This is the reason for mentioning C-b, as it is one way that you can move the cursor into the prompt area.)