How to Close All Terminals with a Bash Script That Effectively Presses Cntrl+Shift+Q in Each Terminal

Casing arrow keys in bash

You can use read -n 1 to read one character then use a case statement to choose an action to take based on the key.

On problem is that arrow keys output more than one character and the sequence (and its length) varies from terminal to terminal.

For example, on the terminal I'm using, the right arrow outputs ^[[C. You can see what sequence your terminal outputs by pressing Ctrl-V Right Arrow. The same is true for other cursor-control keys such as Page Up and End.

I would recommend, instead, to use single-character keys like < and >. Handling them in your script will be much simpler.

read -n 1 key

case "$key" in
    '<') go_left;;
    '>') go_right;;
esac

Zsh zle shift selection

shift-arrow() {
  ((REGION_ACTIVE)) || zle set-mark-command
  zle $1
}
shift-left()  shift-arrow backward-char
shift-right() shift-arrow forward-char
shift-up()    shift-arrow up-line-or-history
shift-down()  shift-arrow down-line-or-history
zle -N shift-left
zle -N shift-right
zle -N shift-up
zle -N shift-down

bindkey $terminfo[kLFT] shift-left
bindkey $terminfo[kRIT] shift-right
bindkey $terminfo[kri]  shift-up
bindkey $terminfo[kind] shift-down

That assumes your terminal sends a different escape sequence upon Shift-Arrows from the one sent upon Arrow and that your terminfo database is properly populated with corresponding kLFT and kRIT capabilities, and that you're using emacs style key binding.

Or, to factorize the code a bit:

shift-arrow() {
  ((REGION_ACTIVE)) || zle set-mark-command
  zle $1
}
for key  kcap seq        widget (
    left  LFT $'\e[1;2D' backward-char
    right RIT $'\e[1;2C' forward-char
    up    ri  $'\e[1;2A' up-line-or-history
    down  ind $'\e[1;2B' down-line-or-history
  ) {
  functions[shift-$key]="shift-arrow $widget"
  zle -N shift-$key
  bindkey ${terminfo[k$kcap]-$seq} shift-$key
}

Above, hardcoded sequences for cases where the terminfo database doesn't have the information (using xterm sequences).

In bash, how do I bind a function key to a command?

You can determine the character sequence emitted by a key by pressing Ctrl-v at the command line, then pressing the key you're interested in. On my system for F12, I get ^[[24~. The ^[ represents Esc. Different types of terminals or terminal emulators can emit different codes for the same key.

At a Bash prompt you can enter a command like this to enable the key macro so you can try it out.

bind '"\e[24~":"foobar"'

Now, when you press F12, you'll get "foobar" on the command line ready for further editing. If you wanted a keystroke to enter a command immediately, you can add a newline:

bind '"\e[24~":"pwd\n"'

Now when you press F12, you'll get the current directory displayed without having to press Enter. What if you've already typed something on the line and you use this which automatically executes? It could get messy. However, you could clear the line as part of your macro:

bind '"\e[24~":"\C-k \C-upwd\n"'

The space makes sure that the Ctrl-u has something to delete to keep the bell from ringing.

Once you've gotten the macro working the way you want, you can make it persistent by adding it to your ~/.inputrc file. There's no need for the bind command or the outer set of single quotes:

"\e[24~":"\C-k \C-upwd\n"

Edit:

You can also create a key binding that will execute something without disturbing the current command line.

bind -x '"\eW":"who"'

Then while you're typing a command that requires a username, for example, and you need to know the names of user who are logged in, you can press Alt-Shift-W and the output of who will be displayed and the prompt will be re-issued with your partial command intact and the cursor in the same position in the line.

Unfortunately, this doesn't work properly for keys such as F12 which output more than two characters. In some cases this can be worked around.

The command (who in this case) could be any executable - a program, script or function.

How to map Ctrl+A and Ctrl+Shift+A differently?

Gvim doesn't do it because vim cannot do it (under normal circumstances). Sorry, but that's just how it is.

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However...

Some terminals (e.g., xterm and iterm2) can be configured to send an arbitrary escape sequence for any combination of keys.

For example, add the following to .Xresources for xterm to send <Esc>[65;5u for CtrlShiftA. You can then map that in Vim to <C-S-a>. (65 is the decimal Unicode value for shift-a and 5 is the bit for the ctrl modifier. The u in this case stands for "unicode".)

! .Xresources
XTerm*vt100.translations: #override Ctrl ~Meta Shift <Key>a: string(0x1b) string("[65;5u")

iTerm and [u]rxvt can also be configured to do this (examples not provided).

More info: http://www.leonerd.org.uk/hacks/fixterms/

In vim how to map save to ctrl-s

Ctrl+S is a common command to terminals to stop updating, it was a way to slow the output so you could read it on terminals that didn't have a scrollback buffer. First find out if you can configure your xterm to pass Ctrl+S through to the application. Then these map commands will work:

noremap <silent> <C-S>          :update<CR>
vnoremap <silent> <C-S>         <C-C>:update<CR>
inoremap <silent> <C-S>         <C-O>:update<CR>

BTW: if Ctrl+S freezes your terminal, type Ctrl+Q to get it going again.

How can I remove the first line of a text file using bash/sed script?

Try tail:

tail -n +2 "$FILE"

-n x: Just print the last x lines. tail -n 5 would give you the last 5 lines of the input. The + sign kind of inverts the argument and make tail print anything but the first x-1 lines. tail -n +1 would print the whole file, tail -n +2 everything but the first line, etc.

GNU tail is much faster than sed. tail is also available on BSD and the -n +2 flag is consistent across both tools. Check the FreeBSD or OS X man pages for more.

The BSD version can be much slower than sed, though. I wonder how they managed that; tail should just read a file line by line while sed does pretty complex operations involving interpreting a script, applying regular expressions and the like.

Note: You may be tempted to use

# THIS WILL GIVE YOU AN EMPTY FILE!
tail -n +2 "$FILE" > "$FILE"

but this will give you an empty file. The reason is that the redirection (>) happens before tail is invoked by the shell:

1. Shell truncates file $FILE
2. Shell creates a new process for tail
3. Shell redirects stdout of the tail process to $FILE
4. tail reads from the now empty $FILE

If you want to remove the first line inside the file, you should use:

tail -n +2 "$FILE" > "$FILE.tmp" && mv "$FILE.tmp" "$FILE"

The && will make sure that the file doesn't get overwritten when there is a problem.

How to stop a command in the Visual Studio Code terminal

You can terminate with the Trash icon like you do,
or press Ctrl + C. That's the shortcut from the default Terminal application and it also works in Visual Studio Code.

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