I've got a Royal Kludge RK61 60% keyboard that has different modes depending on a few different combinations of FN + <ENTER, CTRL, WINKEY>. Unfortunately, there is no actual indication as to which mode the keyboard has selected in any way. I'm looking to change that with my extremely limited bash knowledge by implementing a notification upon key press.
I've done a bit of searching over the past couple days trying to find out the input data for the keys so that it can be incorporated into code.
I found some code that seems to do what I want it, but I think my incorporation of the data needed is flawed, or even wrong.
#!/bin/bash
while true; do
read $key input
if [ "$input" = "keysym 0x1008ff2b" + "keysym 0xff0d" ]; then
notify-send -u normal -i $HOME/Downloads/keyboard_icon.jpeg "Keyboard is now in Function mode:" " Arrow Keys on"
fi
done
Is this correct? How do I ensure that it would be executed without needing the console open?
Is it possible to automatically detect the escape sequence for a key combination?
, i.e., instead of running cat followed by pressing ctrl+right or ctrl+left manually to detect the escape sequence as ^[[5C or ^[[5D respectively, can it be automated? In that case, we may be able to send fn(ctrl+left) or fn(ctrl+right) as input to cat via pipe and get the output(for the first time, when ^[[5C or ^[[5D are unknown) directly.
fn(char a[]='ctrl+right') {..outputs the actual keypress signal for the input string a.. ;} | cat; fn=?
This question is the exact reverse of my other question https://stackoverflow.com/questions/34547008/reverse-map-the-keys-binding-value-to-the-key-combination.
I am asking this to automate the process of setting up key-bindings in the terminals, for devs, so that they need not run manually for all possible combinations, as we had to do now (as seen here)
Is it possible to automatically detect the escape sequence for a key
combination?
Since the shell (as any user program) has no insight into the terminal driver, it cannot predict what the driver will do with a key combination. Consider also that with certain terminals we can change the keyboard's behavior (e. g. cf. xmodmap). Automatic detection is not universally possible.
How can I capture the input/ output from a script in realtime (such as with tee), but line-by-line instead of character-by-character? My goal is to capture the input typed into the interactive prompts of a script only after backspaces and auto-completion have finished processing (after the RETURN key is hit).
Specifically, I am trying to create a wrapper script for ssh that creates a timestamped log of commands used on remote servers. The script, which uses tee to redirect the output for filtering, works well, but the redirected output gets jumbled with unsubmitted characters whenever I use the backspace key or the up/down keys to scroll through my remote history. For example: service test stopexitservice test stopart or cd ..logs[1Pls -al.
Perhaps there is a way to capture the terminal's scrollback and redirect that like with tee?
Update: I have found a character-based cleanup solution that does what I want most of the time. However, I am still hoping for an answer to this question (which may well be msw's answer that it is very difficult to do).
In the Unix world there are two primary modes of handling keyboard input. These are known as 'raw' in which characters are passed from the terminal to the reading program one at a time. This is the mode that editors (and such) will use because the editor needs to respond immediately when you press a key.
The other terminal discipline is called 'cooked' which is the line by line behavior that you think of as the bash line by line input where you get to backspace and the command is not executed until you press return. Ssh has to take your input in raw, character-by-character mode because it has no idea what is running on the other side. For example, if you are running an editor on the far side, it can't wait for a return before sending the key-press. So, as some have suggested, grabbing shell history on the far side is the only reasonable way to get a command-by-command record of the bash commands you typed.
I oversimplified for clarity; actually most installations of bash take input in raw mode because they allow editor like command modification. For example, Ctrl-P scrolls up the command history or Ctrl-A goes to the beginning of the line. And bash needs to be able to get those keys the moment they are typed not waiting for a return.
This is another reason that capturing on the local side is obnoxiously difficult: if you capture on the local side, the stream will be filled with Backspaces and all of bash's editing commands. To get a true transcript of what the remote shell actually executed you have to parse the character stream as if you were the remote shell. There also a problem if you run something like
vi /some_file/which_is_on_the_remote/machine
the input stream to the local ssh will be filled with movement commands snippets of text including backspaces and so on and it would be bloody difficult to figure out what is part of a bash command and what is you talking to the editor.
Few things involving computers are impossible; getting clean input from the local side of an ssh invocation is really, really hard.
I question the actual utility of recording the commands that you execute on a local or remote machine. The reason is that there is so much state which is not visible from a command log. As a simple example here's a log of two commands:
17:00$ cp important_file important_file.bak
17:15$ rm important_file
and two days later you are trying to figure out whether important_file.bak should have the contents you intended or not. Given that log you can't answer that simple question. Even if you had the sequence
16:58$ cat important_file
17:00$ cp important_file important_file.bak
17:15$ rm important_file
If you aren't capturing the output, the cat in the log will not tell you anything. Give me almost any command sequence and I can envision a scenario in which it will not give you the information you need to make sense of what was done.
For a very similar purpose I use GNU screen which offer the option to record everything you do in a shell session (INPUT/OUTPUT). The log it creates also comes with undesirable characters but I clean them with perl:
perl -ne 's/\x1b[[()=][;?0-9]*[0-9A-Za-z]?//g;s/\r//g;s/\007//g;print' < screenlog.0
I hope this helps.
Some features of screen:
http://speaking-my-language.blogspot.com/2010/09/top-5-underused-gnu-screen-features.html
Site I found the perl-oneliner:
https://superuser.com/questions/99128/removing-the-escape-characters-from-gnu-screens-screenlog-n
Every now and then when using the ack-vim plugin the font in my window will change to all symbols. I've yet to see any pattern to when this happens. Any suggestions on the cause and possible remedy would be appreciated.
I've seen that happen when binary content got printed to the terminal. Do your Ack queries potentially include binary files?
A fix might be
:!echo -e '\ec\e(K\e[J'
These ANSI Escape sequences attempt to reset the terminal:
# "ESC c" - sends reset to the terminal.
# "ESC ( K" - reloads the screen output mapping table.
# "ESC [ J" - erases display.
This looks like the typical character set translation enabled by the Shift Out control character; you usually just need to send the Shift In control character to counteract it.
Basically, something is outputting a C-n character (Control-N, U+000E, named Shift Out) which tells your terminal to switch to a different display character set. You should be able to get your terminal to switch back to the normal display character set by sending a C-o (Control-O, U+000F, named Shift In) to it.
If you are in Vim, then you can probably send the C-o with a command like this:
:!printf \\017
You will have to type (or paste) this command “blindly” since (due to the alternate character set) you will probably not be able to read what you are typing. If you are typing it (not pasting), then you can also type C-v C-o (to insert a single, literal C-o) instead of the backslashed octal, if that is easier to remember.
If you find that this problem occurs only sporadically when you use the vim-ack plugin, then perhaps some bit of the text results contains the problematic Shift Out character. You might try searching for the file with a command like this:
grep -FRl $(printf \\016) .
Once you know the names of the files, then you should be able to use Vim to search for the character (start a search and type C-v C-n to insert a literal C-n). Maybe it is just some garbage that you can clean out, or maybe you can configure your ack-based searches to exclude the problematic files.
You also tagged the question with tmux. I can not tell for sure, but it looks like the top line might be a tmux status line. Since this line is also corrupted it indicates that it your external terminal emulator that has switched character sets, not just one of your tmux panes.
If you send Shift Out or Shift In directly to a tmux pane it will only affect that pane (each pane is emulated independently), so your status like could not have been munged just by a stray Shift Out hitting a single pane.
If you are running inside tmux, then the easiest way to reset the outside terminal is to suspend and resume your tmux client (or detach from and reattach to your session). tmux pretty much resets the outside terminal when it gives up control.
Depending on the situation, you may also have to reset the character set of the tmux pane by sending it a C-o, too (i.e. printf \\017 at a shell, or a :! prompt in Vim).
It is easy to see how a stray Shift Out could reconfigure a single tmux pane, but it is harder to see how it could have “leaked” out to reconfigure the external terminal (tmux is pretty good at isolating things like this). However, there is a control sequence that tmux recognizes that instructs it to pass data directly to the external terminal (thus “leaking out”), but it is much less likely that you would randomly encounter this sequence since it is much longer:
printf '\ePtmux;%s\e\\' 'stuff bound for the external terminal'
You could use it to send the restorative Shift In like this:
printf '\ePtmux;%s\e\\' $(printf \\017)
You will also want to tell tmux to redraw itself after this (by default, the refresh-client command is bound to C-b r).
It is probably easier to just suspend and resume (or detach and reattach), but this sequence is useful if that is not possible. It also provides a means toward understanding what kind of sequence might “leak” out of tmux to switch the character set of the external terminal.
Every once in a while I have to fire up a GUI program from my terminal session to do something. It usually is Chrome to display some HTML file are some task alike.
These programs however throw warnings all over the place and it can actually become ridiculous to write anything so I always wanted to redirect stderr/stdout to /dev/null.
While ($PROGRAM &) &>/dev/null seems okay I decided to create a simple Bash function for it so I don't have to repeat myself everytime.
So for now my solution is something like this:
#
# silly little function
#
gui ()
{
if [ $# -gt 0 ] ; then
($# &) &>/dev/null
else
echo "missing argument"
fi
}
#
# silly little example
#
alias google-chrome='gui google-chrome'
So what I'm wondering about is:
Is there a way without an endless list of aliases that's still snappy?
Are there different strategies to accomplish this?
Do other shells offer different solutions?
In asking these questions I want to point out that your strategies and solutions might deviate substantially form mine. Redirecting output to /dev/null and aliasing it was the only way I know but there might be entirely different ways that are more efficient.
Hence this question :-)
As others have pointed in the comments, I think the real problem is a way to distinguish between gui vs. non-gui apps on the commandline. As such, the cleanest way I could think of is to put this part of your script:
#!/bin/bash
if [ $# -gt 0 ] ; then
($# &) &>/dev/null
else
echo "missing argument"
fi
into a file called gui, then chmod +x it and put it in your ~/bin/ (make sure ~/bin is in your $PATH). Now you can launch gui apps with:
`gui google-chrome`
on the prompt.
Alternatively, you can do the above, then make use of bind:
bind 'RETURN: "\e[1~gui \e[4~\n"'
This will allow you to just do:
google-chrome
on the prompt and it would automatically append gui before google-chrome
Or, you can bind the above action to F12 instead of RETURN with
bind '"\e[24~": "\e[1~gui \e[4~\n"'
To separate what you want launched with gui vs. non-gui.
More discussion on binding here and here.
These alternatives offer you a way out of endless aliases; a mix of:
Putting gui in your ~/bin/, and
Binding use of gui to F12 as shown above
seems the most ideal (albeit hacky) solution.
Update - #Enno Weichert's Resultant Solution:
Rounding this solution out ...
This would take care of aliases (in a somewhat whacky way though) and different escape encodings (in a more pragmatic rather than exhaustive way).
Put this in $(HOME)/bin/quiet
#!/bin/bash -i
if [ $# -gt 0 ] ; then
# Expand if $1 is an alias
if [ $(alias -p | awk -F "[ =]" '{print $2}' | grep -x $1) > 0 ] ; then
set -- $(alias $1 | awk -F "['']" '{print $2}') "${#:2}"
fi
($# &) &>/dev/null
else
echo "missing argument"
fi
And this in $(HOME)/.inputrc
#
# Bind prepend `quiet ` to [ALT][RETURN]
#
# The condition is of limited use actually but serves to seperate
# TTY instances from Gnome Terminal instances for me.
# There might very well be other VT emulators that ID as `xterm`
# but use totally different escape codes!
#
$if $term=xterm
"\e\C-j": "\eOHquiet \eOF\n"
$else
"\e\C-m": "\e[1~quiet \e[4~\n"
$endif
Although it is an ugly hack, I sometimes use nohup for a similar needs. It has the side effect of redirecting the command's output, and it makes the program independent of the terminal session.
For the case of running GUI programs in a desktop envinroment it has only little risk for resource leaks as the program will anyway end with window manager session. Nevertheless it should be taken into account.
There is also the option of opening another terminal session. In Gnome for instance, you can use gnome-terminal --comand 'yourapp'.
But this will result in opening many useless terminal windows.
First, it's a great idea to launch GUI applications from the terminal, as this reduces mouse usage. It's faster, and more convenient in terms of options and arguments. For example, take the browser. Say you have the URL in the clipboard, ready to paste. Just type, say, ice (for Iceweasel) and hit Shift-Insert (to paste) and Enter. Compare this to clicking an icon (possibly in a menu), wait for the window to load (even worse if there is a start up page), then click the URL bar (or hit Ctrl-L), then Ctrl-V... So I understand you desire for this to work.
But, I don't see how this would require an "infinite" list of aliases and functions. Are you really using that many GUI applications? And even so, aliases are one line - functions, which may be more practical for handling arguments, are perhaps 1-5 lines of (sparse) code. And, don't feel you need to set them up once and for all - set them up one by one as you go along, when the need arises. Before long, you'll have them all.
Also, if you have a tabbed terminal, like urxvt (there is a Perl extension), you'd benefit from moving from "GUI:s" to "CLI:s": for downloading, there's rtorrent; for IRC, irssi; instead of XEmacs (or emacs), emacs -nw; there is a CLI interface to vlc for streaming music; for mail, Emacs' rmail; etc. etc.! Go hunt :)
(The only sad exception I've run across that I think is a lost cause is the browser. Lynx, W3M, etc., may be great from a technical perspective, but that won't always even matter, as modern web pages are simply not designed with those, text-only browsers in mind. In all honesty, a lot of those pages look a lot less clear in those browsers.)
Hint: To get the most out of a tabbed terminal, you'd like the "change tab" shortcuts "close" (e.g., Alt-J for previous tab and Alt-K for next tab, not the arrow keys that'll make you reach).
Last, one solution that'll circumvent this problem, and that is to launch the "GUI:s" as background processes (with &) in your ~/.xinitrc (including your terminal emulator). Not very flexible, but great for the stuff you always use, every time you use your computer.
Ok, so I kept thinking that the one function should be enough. No aliases, no bashisms, no nonsense. But it seemed to me that the only the way to do that without possibly affecting regular use, such as expansions and completions, was to put the function at the end of the command. This is not as easy as one might first assume.
First I considered a function tacked onto the end in which I would call, say, printf "%b" "\u" in order to cut the current line, plug in another printf, paste it back in, and a quote or two at the beginning, then do what little is needed at the end. I don't know how to make this work though, I'm sorry to say. And even if I did, I couldn't hope for any real reliability/portability with this method due to the varying ways shells interpret escape sequences, not to mention the terminal emulators they run in. Perhaps stty could offer a way forward along these lines, but if so, you won't find it here... now, anyway.
I eventually instead resorted to actually copying the current command's /proc/{PID}/cmdline to a variable, then (shamefully) killing it entirely, and finally wrapping it as I pleased. On the plus side, this is very easily done, very quickly done (though I can imagine arguing its 'efficiency' either way), and seems mostly to work, regardless of the original input, whether that be an alias, a variable, a function, etc. I believe it is also POSIX portable (though I can't remember if I need to specify the kill SIGNALS by name for POSIX or not), and is definitely no nonsense.
On the other hand, its elegance certainly leaves much to be desired, and, though it's probably not worth worrying about, it does waste entirely a single PID. And it doesn't stop completely the shell spam; that is, in my shell I have enabled background jobs reporting with set and so, when first run, the shell kindly informs me that I've just opened and wasted a PID in two lines. Also, because I copy the ../cmdline instead of interfacing directly with the 0 file descriptor, I expect pipes and ; and etc to be problematic. This I can, and likely will, fix myself very soon.
I will fix that, that is, if I cannot find a way to instead make use of, as I suspect can be done,SIGTSTP + SIGCONT by first suspending the process outside a subshell then within one continuing it after redirecting the subshell's output. It seems that this works unreliably for reasons I haven't yet discovered, but I think it's promising. Perhaps nohup and a trap (to effectively rehup it, as it were) is what is needed, but I'm not really sure how to put those together either...
Amyway, without further ado, my semi-aborted, backwards gui launcher:
% _G() { (
_gui_cmd="$(tr '\0' ' ' </proc/"$\!"/cmdline )" ;
kill -9 "$\!" ;
exec eval "${_gui_cmd} &" )
&>/dev/null 2&>1
}
% google-chrome-beta --disk-cache-dir="/tmp/cache" --disk-cache-size=100000000 &_G
[1] 2674
[1] + 2674 killed google-chrome-beta --disk-cache-dir="/tmp/cache" --disk-cache-
%
So another problem one might encounter if attempting to do similar is the order of expansion the shell assumes. Without some trick such as mine you're sure to have some serious difficulty expanding your function before the prior command snags it as an argument. I believe I have guarded against this without unnecessary redundancy by simply tacking my _G function call onto the original command's & background intstruction. Simply add &_Gto the tail-end of the command you wish to run and, well, good luck.
-Mike
P.S. Ok, so writing that last sentence makes me think of what might be done with tee.