Now i try find the way to prove that a clear command is working correctly on my own REPL
Example
$ cd ~
$ pwd
/home/user
$ echo "hello"
hello
then type clear
$
but sometime some unexpected behavior is occurred after using a clear command
e.g.
[one blank line here]
$
A one blank line after using clear command is undesirable behavior and I hope this kind of bug can be detected automatically via a unit test. If you have any idea to prove that clear command is working correctly please purpose.
There is no easy way to do this. "clear" sends a sequence of bytes that tells the terminal to clear its screen. Different terminals use different sequences. There is a table called "termcap" (terminal capabilities) that lists the difference sequences for different types of terminals. The environment variable "TERM" should be set to the type of terminal you are using.
TERM is usually set to "xterm", "xterm-color", "vt100", or related value. On my Mac OS X Terminal it is set to "xterm-256color".
TERM should be set automatically for you. If your OS is set up properly you shouldn't have to set it yourself. However in the old days you had to set it manually. Therefore you'll find a lot of old .profile/.bashrc/.cshrc files that set it. Check to see if that is happening and remove that (comment it out) to see what is automatically set.
Your question boils down to "how can I tell if my TERM variable is set right?" and the answer is: You can't. You could do things like clear the screen then ask the user if they saw their screen clear. However, if programs did that on start-up, it would be very annoying.
Related
I've been wondering how I could do some of these cool customization options for the terminal on a Mac and I came across lolcat.
However, I can't seem to find an answer as to how to add this into my bashrc (FYI: I'm using zsh now just in case that makes a difference as to which file to add my customizations in) I have tried what many others have suggested, which was just typing zsh | lolcat into the terminal to get rainbow output in the current session, but I was wondering how I can have this every time I start a terminal session.
Also, I'm not sure if this is a bug or if there's something wrong with my terminal settings, but when I use a command with lolcat, I get an output like this:
karenlee#Karens-MBP ~ % Documents
Downloads
Library
Movies
Music
Pictures
Postman
Public
38;5;48m
karenlee#Karens-MBP ~ % 38;5;48m
The colors look right, but as you can see, when I type the ls command on the command line, it disappears and the output also gets messy. It also seems like there's extra lines of 38;5;48m which are appearing. And it also seemed like many of the gems that are installed with lolcat have deprecated; is there another alternative to lolcat that plays nicely with macOS Catalina?
I made a shell extension for the world's fastest website generator that I make called Nift. It has an easter egg where you can turn on lolcat output for most things with lolcat.on (after starting the shell with eg. nift sh). You will even get rainbow output when pressing tab to get possible completion options, I doubt you get that with any other suggested solutions.
The shell extension is for f++ which is the in-built scripting language, which has these functions and these types available. But anything it doesn't recognise is run as a system call using the (probably primary/default) shell on your machine (hence calling it a shell extension in REPL shell mode).
Nift will look for a version of lolcat installed on your machine and otherwise use an in-built version of it which should be the world's fastest (it's near identical to my c++ implementation lolcat-cc which is the world's fastest). I highly recommend installing lolcat-cc (or another version of lolcat) on top of Nift though as otherwise you are frequently running the ~5mb Nift binary for basically all system calls, instead of a <1mb binary for lolcat.
f++ is somewhat of an interesting scripting language as well. Take this script for example which creates and deletes 100k empty text files. On my machine this runs in ~3.5 seconds whereas this Bash script doing essentially the same thing takes more like 3 minutes!! Some of the cool things you might already notice from that f++ script is you can expand variables inside strings, you can define variables with types, you can expand variables in to multiple parameters with function calls, you can have LOTS more than 10k input parameters for function calls (should be able to have millions!).
You can find some more information about the Nift REPLs (including shortcuts for different platforms) here.
If you need to define shell variables (not through f++ but the underlying shell) then you will need to do blocks of code using the sys/system function. You can also do blocks of code for Lua(JIT) and ExprTk similarly as they are both embedded in to Nift. You can use both Lua and ExprTk with accessing/modifying f++ variables as well..
So to get this shell (extension). Install Nift through a package manager or clone, make and install off GitHub. Enter nift sh in to your terminal to start the Nift f++ shell extension, then enter lolcat.on to turn on rainbow output.
My shell is GNU Bash 4.3.11, and I currently have M-h bound to cd .. by calling the builtin
bind -x '"\eh": "cd .."'
This gives me a nifty way to navigate up the directory tree, as I can repeatedly hit M-h instead of the incredibly time-consuming cd ... It has the downside, however, either of not resetting my $PS1 or of not redrawing my prompt, so I lose the context of my current working directory until I enter a new command.
One alternative I'm aware of is to put a macro like
"\eh": "\C-a\C-kcd ..\C-m"
in my .inputrc directly. This, however, has the downside of not only losing the context of any existing command I'm typing in (which I think can probably be worked around) but also of printing out cd .. (which I don't think can be).
My desired behavior is to be able to be in a directory ~/one/two with prompt ~/one/two$; hit M-h; and then be in ~/one and have the prompt be ~/one$, ideally keeping any command I had initially. How can I achieve this?
Figured this out.
# maintain state
bind -x '"\200": TEMP_LINE=$READLINE_LINE; TEMP_POINT=$READLINE_POINT'
bind -x '"\201": READLINE_LINE=$TEMP_LINE; READLINE_POINT=$TEMP_POINT; unset TEMP_POINT; unset TEMP_LINE'
# "cd .." use case.
bind -x '"\206": "cd .."'
bind '"\eh":"\200\C-a\C-k\206\C-m\201"'
I'm quite late to that party - and came here looking for that answer also. First of all: As you were the only one providing information on this: thanks for not letting it come to this: https://xkcd.com/979/ ;) instead you pointed me to the on corner in that fractal that seems to hold a solution.
This approach, in my opinion backed up by hours of trying, is the only one where you can a) replace content on the line, and b) execute bash code. Let me offer up some more suggestions to a specific problem:
If you are trying to have it both ways: insert something on the command line, or executing code, things can get very tricky. for both, there exist bindings, and I let the reader figure out things with help bind. But in the case you e.g. have FZF produce some directory as output, and you'd either cd to it, or have it pasted into your command -- depending on the keystroke done in FZF -- things will get near impossible. you'll face either the not-updated-promt problem, or not be able to execute the cd command in the top shell (where it has effect).
Your solution would be a multiplexing -x binding, inspecting the output for "macros" (get extracted and eval'd) or the default pass-through (manipulating READLINE_LINE/POINT).
Because the solution has some enormity, and the audience may be limited (closed answer...), I'll leave it at a haphazard gist where I pasted my code which works now. To make up for the brevity and uncommented-ness, I welcome any questions in comment or elsewhere. Hope someone may be pointed in the right direction.
- The code related to this question starts in function bindInsertEvalWithMacrosVi
- It is designed for Vi keybindings but the same principles apply for normal readline mode
- It depends on some \C-x\C-... combinations to do redrawing in places that are not related to this post.
https://gist.github.com/simlei/032470cfcd23641987f97a96749128d7
Is there any way to have ksh display the current typing mode at the bottom of the window like vim; like "Insert", "Command", "Visual", etc? Unfortunately, I am having a lot of trouble remembering which mode I'm in and find the shell unintuitive (at least until I get used to all the commands). I consistantly hit the wrong key in command mode and have difficulty figuring out how to get back to proper typing (sometimes it lets me type but not delete part of the line and I don't know why).
I am required to use ksh for work and am heavily restricted in what I can download and install, but I need to figure this out. Hopefully there is something I can do with a profile or script along these lines to help ease the transistion. Also, this is HP-Unix, in case that affects anything.
This set -o alone command will show if emacs is defined to on
$ set -o|grep emacs
emacs on
On my bash prompt, I would like to see just the name of the current directory followed by "$" in different colours.
So I used this code but when I have a long typed command, I see the cursor in different place than where the typing is taking place. How can this "hard to describe" problem be fixed? Thanks
PS1='\[\e[0;36m\]\W\[\e[m\]\[\e[1;31m\]\$\[\e[m\]'
Use a carriage-return after outputting the current directory, I've done this for years and it works a treat, something like:
if [ "$PS1" ]; then
PS1="\[\e[0;36m\]\W\n\[\e[m\]\[\e[1;31m\]\$\[\e[m\]"
fi
You always have your current directory (no matter how long) on top of your $ prompt.
I put other info up there as well like username, machine name and exact time and date. I colour them differently so they really stand out. Helps if you have multiple sessions going on, on different machines with or without root(!) privileges (have to be root when deploying a complete rebuild). And has saved the day many times when I need to know when I did something or other (ok, it's when that task ended - but still helps).
But most of all, it's great to know your current directory by simply looking at your command line prompt :) )
Don't know how other people work efficiently without it!
Open up irb and
type gets. It should work fine.
Then try system("choice /c YN") It should work as expected.
Now try gets again, it behaves oddly.
Can someone tell me why this is?
EDIT: For some clarification on the "odd" behavior, it allows me to type for gets, but doesn't show me the characters and I have to press the enter key twice.
Terminal input-output handling is dark and mysterious art. Anyone trying to make colorized output of bash work in windows PowerShell via ssh knows that. (And various shortcutting habits like Ctrl+Backspace only make things worse.)
One of the possible reasons for your problem is special characters handling. Every terminal out there can type characters in number of different modes, and it parses its own output in search for certain character sequences in order to toggle states.
F.e. here one can find ANSI escape code sequences, one of possible supported standards among different kind of terminals.
See there Esc[5;45m? That will make all the following output to blink on magenta background. And there is significantly more stuff like that out there.
So, the answer to your question taken literally is — your choice command messes something with output modes using special escape sequences, and ruby's gets breaks in that quirk special mode of terminal operation.
But more useful will be the link to HighLine gem documentation. Why one might want to implement platform-specific and obtrusive behavior when it is possible to implement the same with about 12 LOC? All the respect for the Gist goes to botimer, I've only stumbled into his code using search.