Under Ubuntu 14.04, I'm writing a script that output a lot of text (several commands...), and I would like to keep one or more lines always on top of the terminal screen to display what's running title.
In other words, I try to reduce terminal vertical scroll zone and write in that non-scrolling zone.
How can I do that? I saw similar stuff using a loop catching output line by line, but I'm unable to find a way to tell the system to print from let's say line 2 or 3.
Thanks for your answers,
Nicolas
Nic, it appears this does quite nicely.
http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x361.html
Related
sometimes in terminal when I type a long command, instead of continuing in the next line it starts to write at the same line and I cannot see what I am typing. What is the reason and how should I make it fine?
Sometimes if you resize a terminal window while in a fullscreen command (say inside "vim" or "less"), when you exit back to the shell it will assume your terminal has the old dimensions, and will show the behavior you are describing. See this question: https://unix.stackexchange.com/questions/61584/how-to-solve-the-issue-that-a-terminal-screen-is-messed-up-usually-after-a-res
Also, please in the future post this kind of questions in unix.stackexchange.com as this one is not strictly a programming question.
I am trying to create a program which will have live updates from some data source. And I also want to wait for user input just like a normal terminal. Right now, whenever there is update, I will print the content and print the prompt message for input again which create something like this:
Enter command >
This is a live update message
Enter command >
This is a multi-line li......
......ve update message
Enter command > quit
Bye bye!
The problem is that for every live message I received, I will print it and the "Enter command >" will be displayed again again and again, which is not desired. I want the live update to be update on the main part of the terminal, while the "Enter command >" always stay at the bottom
The closest package I can found on Github is https://github.com/gizak/termui but most of the examples inside is trying to display text, gauge and graphs. So I am not quite sure how to get started.
Is there any package or example of the termui package to achieve this? Thank you.
With github.com/gizak/termui you're heading in the correct direction.
To understand why you can't get that
I want the live update to be update on the main part of the terminal, while the "Enter command >" always stay at the bottom
part sorted out, a little excursion to the history of computing is due. ;-)
The thing is, the mode your teminal emulator¹ works by default originated
in how computers would communicate to the operator in the era which predated
alphanumeric displays — they would print their responses using a line printer. Now think of it: a line printer works like this: it prints whatever is sent to it on a roll of paper. What was output, was output.
The new output always appears physically below the older.
When alphanumeric displays (screens) came into existence they
naturally continued to support this mode:
the line text to be output was rendered at the bottom of the screen
with the text above it scrolled upwards.
That's what you see in your typical terminal emulator all the time when you're working in the command line of a shell (such as bash) running by the emulator window.
This, default, work mode of a terminal is called "canonical" or "cooked".
Then came more advanced displays, for which it was possible to change
individual positions on the screen — identified by their column and
row numbers.
This changed the paradigm of how the information was output: the concept
of a so-called "full-screen application" was born.
Typical examples of them are text editors such as Vim and Emacs.
To support full-screen text output, terminals (and terminal emulators)
were adapted by implementing certain extensions to their protocols.
A full-screen application first requests the terminal to switch into another
mode called "raw", in which the terminal sends most of what is input by the
user directly to the program running on the terminal.
The program handles this input and orders the terminal where and what
to draw.
You can read this good summary
of the distinction between the both modes.
As you are supposedly suspecting by now, to be able to keep some block
of information at a certain fixed place of the terminal's text screen,
you want your program to be a full-screen program and use the terminal's
raw mode and its special commands allowing you to directly modify
text at certain character cells.
Now the problem is that different terminals (and terminal emulators)
have different commands to do that, so there exist libraries to isolate
the programs from these gory details. They rely on the special "terminal
information databases" to figure out what capabilities a terminal has
and how to make it do what the program asks.
See man terminfo for more background.
The most widely known such library (written in C) is called ncurses,
and there exist native solutions for Go with supposedly the most visible
one being github.com/nsf/termbox-go.
The github.com/gizak/termui makes use of termbox-go but for you it might
suffice to use the latter directly.
¹ Chances are very high you're not sitting at
a real hardware terminal
connected to a UNIX® machine but are rather working in a GUI application
such as GNOME Terminal or xterm or Termial.app etc.
These are not "terminals" per se but are rather
terminal emulators —
that is, pieces of software emulating a hardware terminal.
Under Ubuntu 14.04, I'm writing a script that output a lot of text (several commands...), and I would like to keep one or more lines always on top of the terminal screen to display what's running title.
In other words, I try to reduce terminal vertical scroll zone and write in that non-scrolling zone.
How can I do that? I saw similar stuff using a loop catching output line by line, but I'm unable to find a way to tell the system to print from let's say line 2 or 3.
Thanks for your answers,
Nicolas
Nic, it appears this does quite nicely.
http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x361.html
As it is right now, it has become rather annoying having to wade through old result texts through iTerm trying to distinguish where my command line was and what the resulting text is.
Is there a way to make it easier for me to clearly identify my command line?
I was thinking I could set it a different color than my result text.
You can setup your shell prompt in a different color please have a look at following two links, one for bash and the other for zsh.
Remember if you ssh to a different host you most likely will lose the color unless you have exactly same settings on that host.
on-my-zsh
crazy bash prompt
Is there a way to set the mac terminal to output its lastest output in a different color?
I am tired of wasting time looking for the last command when the terminal gets filled.
No, but you could arrange for your prompt to be in a different color. You could also split the pane; the bottom will scroll with the output while the top stays wherever it was.