In bash, how does one clear the current input? - bash

Suppose in bash you start writing a command like:
$ rm -rf /foo/bar/really/long/path/here
and then realize you don't want to execute this after all. Is there a way to clear the input with one or two keystrokes?
What I have been doing lately is prepending echo and enclosing the input in quotes (Ctrl+A, echo ", Ctrl+E, ") then hitting enter. Is there a faster way?

Press Ctrl-U to delete everything before the cursor. The deleted command will be stored into a buffer. Press Ctrl-Y to paste the deleted command.
(Optional: Press End or Ctrl-E to jump to the end of the input first.)
Alternatively, press Ctrl-C to abort what you're typing.

Try Ctrl+U. That clears the input line.

Found a short reference at http://www.ice2o.com/bash_quick_ref.html while searching.
ctrl + e (if not at the end of the line) plus ctrl + u will do it.

Ctrl-U, Ctrl-K does the trick as well.
Ctrl-U deletes everything from the beginning of the line up to the cursor, Ctrl-K deletes everything from the cursor to the end of the line. (It is sometimes useful to use only one of them.)

There are two options to do this
ctrl+c - this clears the whole line, no matter where the cursor is.
ctrl+u - this clear the line from the position of the cursor until the beginning.

A nice shortcut is pressing Esc#. It will prepend a # character (thus making the line a comment) and then press enter. If you then decide that you still the need the command, you still have it in your history :)

Pressing Esc plus Backspace in bash will clear everything up to the cursor's position.
(In Cygwin, this will clear the input up to the next word. Words are separated by spaces, underscores, ...)

This is an expansion of knittl's answer that stores the line in the console history by prefixing with a hash. Overcoming drawbacks of the clipboard, such as accidental overwriting or being unable to view the cut line for reference.
Comment Line & Return New Prompt
Use either key shortcut:
Esc,#
Alt+#
A hash character # will be prepended to the line, thus turning the whole line into a comment. It will also return a new prompt, as if enter was pressed by the user. e.g.
$ #rm -rf /foo/bar/really/long/path/here
$
Retrieve Commented Line
To recover the old line from console history use one of the following shortcuts:
Up
Ctrl+p
Repeat key shortcut until the desired line appears.
Quick Hash Prefix Removal
To remove the line's hash # prefix there are a few different options available:
Remove first character and immediately execute command:
Esc,1,Esc,#
Alt+-, Alt+#
Move cursor to start and remove first character, without executing the command:
Home, Delete
Ctrl+a, Ctrl+d

Consider that using Ctrl-U (or Ctrl-E and then Ctrl-U) will store what you clear in a buffer so that you can then paste it later using Ctrl-Y.

If you are using Bash in vi mode (set it with set -o vi), then press Esc to switch to the normal mode of vi, and type dd to delete the current line!

To delete the current line, try:
Ctrl-X, Ctrl-U
As an alternative you may use:
Esc-D
which requires in ~/.inputrc:
"\ed": kill-whole-line
see: http://codesnippets.joyent.com/posts/show/1690

Related

Shortcut to jump to the previous white space in a bash command line

To jump to the previous word in a command line, I use Alt + b.
However, the names of my files are pretty long and look like this:
2018_09_03_abcdef_ghijkl_mnopqr_stuvwx_yz.txt
When I want to change the name of these files, I use the command mv and a shortcut** that permits me to paste the first word/argument (the current name of the file). This gives me the following command:
$ mv 2018_09_03_abcdef_ghijkl_mnopqr_stuvwx_yz.txt 2018_09_03_abcdef_ghijkl_mnopqr_stuvwx_yz.txt
Then I either want to change the date of the day and/or the first letters of the file name to get for example the final command line:
$ mv 2018_09_03_abcdef_ghijkl_mnopqr_stuvwx_yz.txt 2018_09_04_ABcd1234_ghijkl_mnopqr_stuvwx_yz.txt
To make the change at the beginning of the file name, I have to type the shortcut Alt + b several times since this shortcut considers every letters separated by an underscore as a word.
I would like to be able to jump directly to the beginning of the name (not the beginning of the line) to modify it. A shortcut targeting the white space would be ideal.
I have not been able to find such a shortcut that would skip the underscores and go directly to the previous white space.
Did anyone already create a shortcut in bash that allows you to do this?
Would the only possible way to accomplish this be to switch from emacs mode to vi mode (set -o vi) and use the vi shortcut:
F + space
?
Thank you very much in advance!
** The shortcut I found to paste the previous word in the current command line and paste it in the same current command line uses Alt + j and has to be added in the '~/.inputrc' file (followed by bind -f ~/.inputrc):
"\ej":"!#:$\e^"
There are several shortcuts to navigate bash command line. Here's another list.
Assuming cursor is at the end of the line, it could jump to 03 (day part) by typing Meta+7 Meta+b (2 keystrokes without releasing Meta key).
Now, for the file name changes, brace expansion could be used to get a command like this that provides the second argument from expansion.
mv 2018_09_{03_abc,04_ABC}def_ghijkl_mnopqr_stuvwx_yz.txt

Jump to string in current line while using Bash in VI mode

While navigating in BASH using VI mode, I can jump back to a specific character (e.g. '-') of the current command line via the following command:
F-
How can I jump back to a specific string (e.g. '--path') in the current command line of BASH? I know navigating in VI but I did not understand how to perform regex search in current command line of BASH.
According to here, what you want doesn't seem possible. The ?word and /word bindings search in command history rather than in the current command line.
But in vi mode, you can press ESC v to open the current command line in an editor. Then you can edit & save the command and it will be executed (source).
Of course, as pointed out in nur-sh's answer, you can simply keep pressing B to get to the word.
You could use the find command which searches backwards from where you are
?word
or you could keep pressing B to get to the word
(this command goes back one Word at a time).

zsh command line editor: go back to previous lines when entering a command

Note that I'm NOT talking about previous lines in the history. I'm talking about previous lines in the current multiline command.
When I type a multiline command in zsh, for instance (_ indicates the cursor):
$ for i in {1..5}; do
for> echo i_
At this point I might change my mind and want to let i loop through {1..10} instead, so I need to go back to the previous line. However, I can't figure out how to do this, as ⌫, or ←, or C-b, or whatever I can think of all stops at the beginning of the second line. So, is it possible at all to move back? Thanks in advance.
In fact, this is not limited to zsh. For instance, I've never figured this out in bash either.
I've already spent a fair amount of time Googling without any findings, so please excuse me and blame my Google-fu if this is obvious.
For your reference, I'm using Emacs keybinding, and
$ bindkey | grep delete
"^D" delete-char-or-list
"^H" backward-delete-char
"^[[3~" delete-char
"^?" backward-delete-char
Not sure whether this will help.
Here is how you would visual mode in bash's vim mode.
Inside .bashrc put the following lines.
set -o vi
# I do not remember which one of these is used by `v`, so I set both
export VISUAL=/usr/bin/nano
export EDITOR=/usr/bin/nano
Reload bash, and then push Esc to go into normal mode.
Type v, and nano should load. You can now enter your multiline command into nano. When you save and exit, the multiline command will be executed.
For zsh, the following lines in your rc may do it. I stole the last three lines from this answer and tested it on my zsh.
bindkey -v
autoload -U edit-command-line
zle -N edit-command-line
bindkey -M vicmd v edit-command-line
Actually this is possible.
While on that second line, pres Esc + X in order to execute a command,
and type push-line-or-edit (note that you can use Tab key for completion)
, then press return.
The prompt will change to a traditional one ditching your for> part from
continuation line, and you will have a new buffer filled with all your
previously typed lines, which of course now you can easily edit using well
known C-a or C-b keys.
I do not think this is possible, but here are other workarounds:
You can just write everything in one line. It is not easy to edit, but multiline strings are not easily editable either.
You can bind some key (e.g. <C-Enter> if you can tell your terminal not to output <C-m> in this case) to
function _-add-newline()
{
LBUFFER="$LBUFFER"$'\n'
}
zle -N add-newline _-add-newline
bindkey "\Ca" add-newline
. This way if you press <C-a> newline will appear in the buffer, but it will not trigger accept-line widget and previous line will still be editable. You can e.g. use left/right arrows to move to it.
If you type for x in y ; do<CR>echo foo<CR><C-c><Up> you will see for x in y ; do\necho foo in your buffer and all text will be editable. Note: you need <CR> to preserve last line (line aborted by <C-c> is not saved) and <C-c> to abort input; this variant will not work if you have already typed done (first <CR> will run the cycle). In last case you may discard last line with <C-c> and retype it.
Theoretically you may override accept-line widget with a code that parses your input and determines whether you have written command completely and if not then it will just append \n to the buffer (like in the above function) and do not run original accept-line, otherwise original accept-line is run. This variant is much harder to implement though, so I am saying “theoretically”.

On bash command-line, how to delete all letters before cursor?

On bash command-line, how to delete all letters before cursor? I know Ctrl-k deletes all afterward the cursor.
Ctrl-u - Cut everything before the cursor
Other Bash shortcuts,
Ctrl-a Move cursor to beginning of line
Ctrl-e Move cursor to end of line
Ctrl-b Move cursor back one word
Ctrl-f Move cursor forward one word
Ctrl-w Cut the last word
Ctrl-k Cut everything after the cursor
Ctrl-y Paste the last thing to be cut
Ctrl-_ Undo
And discover more via man page for bash shell: man bash
Additional bash command-line shortcut cheat sheet: http://www.bigsmoke.us/readline/shortcuts
See the documentation here: http://www.gnu.org/software/bash/manual/bashref.html#Commands-For-Killing
Obligatory: Learn more about Bash, Linux, and Tech through Julia's comics: https://twitter.com/b0rk/media
In zsh, Alt+w clears all characters before the cursor.
In contrast to bash this does NOT cut them; it just deletes them.
This applies to zsh's Emacs mode (which is the default), NOT to Vi mode.
The hotkey Ctrl+U should do this for you.
Ctrl+x backspace clear all entry before cursor current position

Going backwards in a bash prompt

I'd like to have a blank line after my bash prompt and before the output on my Mac. It should look like this would:
echo; ls
Can I add a newline to my bash prompt and then go back up one line to wait for user input? Is there something obvious I'm missing?
I know this is old but for someone like me who came across this while googling for it. This is how you do this...
It's actually pretty simple!
Check out this link --> Cursor Movement
Basically to move up N number of lines:
echo -e "\033[<N>A HELLO WORLD\n"
Just change the "< N >" to however many lines you want to go back...
For instance, to move up 5 lines it would be "/033[5A"
To my knowledge this is not possible unless you delve into more low-level stuff like full-screen emulators like curses.
This is a bit of a stab in the dark, but you may be able to use VT102 terminal codes to control the cursor without having to use Curses. The relevant VT102 commands that you'd be interested in all consist of sending ESC, then [, then the specific command parameters.
For instance, to move the cursor up one line, one needs to output:
ESC [ 1 A
0x1B 0x5B 0x31 0x41
Be warned that the VT102 documentation generally uses octal, so keep an ascii table handy if you're using hex.
All of this advice is given without having tested it -- I don't know if VT102 commands can be embedded into your bash prompt, but I thought it might be worth a shot.
Edit: Yeah -- looks like a lot of people use VT102 formatting codes in their bash prompts. To translate my above example into something Bash would recognize, putting:
\e[1A
into your prompt should move the cursor up one line.
This is very possible. If your bash has C-v set as the readline quoted-insert command, you can simply add the following to your ~/.inputrc:
RETURN: "\C-e\C-v\n\C-v\n\n"
This wil make bash (readline, actually) insert two verbatim newlines before a regular interpreted newline. By default, only one is inserted, which is what causes output to start on the line after the prompt.
You can test if C-v is set to quoted-insert by typing it in bash (that's Ctrl+V) followed by e.g. an up arrow. This should print ^[[A or something similar. If it doesn't, you can bind it in ~/.inputrc too:
C-v: quoted-insert
RETURN: "\C-e\C-v\n\C-v\n\n"
~/.inputrc can be created if it doesn't exist. The changes will not take effect in running bashes unless you issue a readline re-read-init-file command (by default on C-x C-r). Be careful though. If you do something wrong, enter will no longer issue commands, and fixing your mistake could prove to be difficult. If you should do something wrong, C-o will by default also accept the line.
Adding a newline followed by moving the cursor back to the regular prompt (like you described) is possible, but will not have the effect you intend. The newline you inserted would simply be overwritten by the application output, since you moved the cursor back in front of it.
This works:
trap echo DEBUG
It doesn't add an extra newline if you hit return at an empty prompt.
The command above will cause a newline to be output for every member of a pipeline or multi-command line such as:
$ echo foo; echo bar
\n
foo
\n
bar
To prevent that so that only one extra newline is output before all command output:
PROMPT_COMMAND='_nl=true'; trap -- '$_nl && [[ $BASH_COMMAND != $PROMPT_COMMAND ]] && echo; _nl=false' DEBUG
The DEBUG trap is performed before each command so before the first command it checks to see if the flag is true and, if so, outputs a newline. Then it sets the flag to false so each command afterwards on the line doesn't trigger an extra newline.
The contents of $PROMPT_COMMAND are executed before the prompt is output so the flag is set to true - ready for the next cycle.
Because pressing enter on an empty command line still triggers the execution of the contents of $PROMPT_COMMAND the test in the trap also checks for those contents as the current command and doesn't perform the echo if they match.
I believe (but haven't tried) if you put '\n\b' in the prompt string it would do that.
In general, if you want to find out the codes to do anything a terminal can do, read the terminfo man page.
In this case, the cursor up one line code can be determined by:
tput cuu1
If you redirect the tput output to a file, you can see what control characters are used.
Bash also supports the PROMPT_COMMAND variable, allowing you to run arbitrary commands before each prompt is issued.

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