\ is the line-continuation character in
bash just like in C (for #defining a long macro) or several other computer languages, allowing wrapping long lines in the source without changing the meaning in a line-oriented language.
It Just Works with a single paste if the selection doesn't include any spaces after the
\ characters, only a newline. (In Chromium, that shows up as one blue character "box" that looks like a space at the end of the line, but apparently that's actually the newline.) Some web pages include trailing spaces in their formatted code. Perhaps the author copy/pasted from a terminal including spaces out to a fixed width and didn't clean it up for their code block.
You can tell this visually by selecting the whole thing and looking at the line endings. If it's good, you can just paste into a terminal. If not, you can paste into an editor and collapse the
\ ... spaces newline yourself.
Or if it's not too complicated, you may be able to paste inside single quotes on the command line and then use up-arrow to fix it.
Or paste each line separately if that will be easier for you, leaving out the
\... creating one long line. Or even manually include the
\ but not trailing spaces or newline in your copy, then hit return after pasting each line.
Chromium at least allows you to adjust your selection with shift+left/right arrow if you're having trouble getting all the chars you want with the mouse but not chars you don't want.
Stack Exchange code formatting blocks can faithfully reproduce both good and bad examples so you can give it a try in your browser to see what to look for.
echo 1 \
# Bad: spaces after backslash: needs editing to copy/paste
echo 1 \
paste result: the
\ only escapes a space, not a newline. The individual lines are each harmless on their own, so it's safe to play around with. Not like a
rm * that's supposed to be part of something else, or starting any real programs, unless you have aliases or shell functions called
2 or 3`.
peter@volta:/tmp$ echo 1 \
peter@volta:/tmp$ 2 \
bash: 2: command not found
bash: 3: command not found
One quick way to fix without starting up a separate editor:
Paste inside single quotes:
$ 'echo 1 \
> 2 \
> 3 '
bash: $'echo 1 \\ \n 2 \\ \n 3 ': command not found
Note that bash used
$'C-escaped' syntax to quote the command back to me. I did actually hit return to get the whole thing into command-line history. Bash line-editing won't go back to a previous already-submitted line, but multi-line quoted things do create a single multi-line history entry.
Up-arrow from there gives me all of that as a single command with embedded newlines that you can edit. You need to remove those or it will still be interpreted as multiple commands, like if they were
; semicolons. Also of course remove the
Ctrl-w (unix-word-rubout) treats
\ as a "word", and stops after it. (Unlike M-d (escape-d) to delete forward word, or M-backspace (delete backwards word); those would delete the word past the backslash). Ctrl-w even treats newline as a "word" (which is actually not what we want; from the first non-whitespace character we'd like to just kill to the
\ on the previous line).
ctrl-left (or escape-f) / ctrl-right (or escape-b) move the cursor by whole words so you can quickly get to the start of a "line" for control-w. Or ctrl-r to reverse i-search for
\ can get you there, then ctrl-right + left to get to the first word of the next line.
Ctrl-/ is undo, which is really handy because it lets you be aggressive with key-repeat or whatever, and quickly recover from overshoot.
If you use bash / readline line-editing regularly, you'll already remember many of these commands. I mention them here only for the benefit of people with less experience with bash line-editing who might think it was worth copy/pasting into an editor and then into bash. That's certainly an option, especially if you have an editor already open.
Another possibly useful editing command is M-\ (meta/escape backslash). That removes whitespace surrounding the cursor. You could just use that twice, with the cursor after the
\ on the, to leave it as a multi-line thing with
\ continuations. For example, recall the command with up-arrow
- backspace / ctrl-a / delete (or ctrl-d) to remove the single quotes
- ctrl-s forward i-search for
\, then right arrow (or ctrl-f) to move the cursor onto the space after the
\. (Or alt-
\ if your terminal is properly set up for that to work as emacs line editing meta-, normally by sending an escape prefix.)
- ctrl-s ctrl-s to forward i-search for the same thing again
- repeat the right arrow + kill whitespace
(I'm not suggesting memorizing these steps, this is just one way of using line-editing to get the job done.)
Or you can remove the
\ and newline (and collapse whitespace down to 1 space if you want), like I suggested with control-w. Delete / ctrl-d or backspace will remove a newline or backslash when you have the cursor in the right place. Bash line-editing apparently doesn't have emacs
M-space to collapse whitespace to 1 (instead of 0) spaces, but you can do that manually with M-
\ + space.