Reverting direction in terminal - linux

When I am typing in the terminal, I always have the last command at the bottom, which means I always need to look down at the screen, even If I want to look at the top and look down for the buffer.
Instead, I would like to have the latest command at the top of the terminal. Are there any options on how to achieve this? Something like running tac interactively on the terminal?

Related

In Bash, how do I display script output and then resume to the previous output (like less, or top, or watch)

I don't want to write C code for this,
But I want my script to behave like 'watch': display output on a clean console, and eventually return to the original output that was displayed.
I'm not using watch because it messes with my output and lack functions I want to add.
Regular 'clear' will fill up my console with pages and pages of the same output and I want to avoid that.
Any suggestions?
Terminal curses software such as ncurses should work as well as making 'q' to quit like less fairly simple

Go to beginning of output command created - shortcut

I can scroll trough bash output using shift+pgup/pgdown.
But lets say, some command outputted lot of text, I have to pageup few times to go to beginning of output of this command.
Can I just simply do this by some shortcut? Something that simply allows me to scroll between previous commands (not history!), seeing their output.
You could try piping the output into less:
someCommand | less
less will allow you to search and scroll through the output text pretty easily.
once in less you can just type % to jump back to the top of the page. Essentially that means jump to 0% of the page. There are also a bunch of extra commands on the page I linked to above.
Another option is to use screen and use backward search (beware: read the Overview first, especially the part about the C-a prefix) to e.g. search for some specific characters in your prompt (like your username).
The scroll back history in Unix shells is a shell specific functionality, meaning that it is up to the specific shell (xterm, rxvt, text console, etc) to handle it. The functionality you request would require the shell to identify the individual program runs, to know where to scroll to. Scanning text is not technically hard per se, but as prompts and command display can differ due to user settings it can be hard to make it work generally good. Some communication between the shell and the terminal could make it better.
There sure are some nice fancy terminal programs doing things like this, to for example show syntax help when writing commands, but for your case I agree with previous answer, that piping commands to less is a good way to isolate the output. It might be a bit cumbersome first, as it requires you to think about it first, and not just go back in history, but if you learn the shell better and learn to use the command history it will probably work fine. I recommend you to, if you haven't already. What I mean is ctrl-r etc. More described for example here:
http://www.catonmat.net/blog/the-definitive-guide-to-bash-command-line-history/

Run a Command When Terminal Opens (Linux)

This feels like a stupid question, but I can't find an answer (that works) anywhere. So, I thought I'd ask it here.
Basically, I would like a command to run every time I open a Terminal window, and then show the output in the Terminal (I have Fedora). Is this possible with the MOTD, or is that text-only?
Thanks!
Put it in ~/.bashrc or equivalent.

Node command line interface change

I'm making a command interface for a node server, but I have reached a point that I want it to look better.
I want to have the console so you enter a command at the bottom of the terminal screen, you hit enter, and it adds the reply to the actual command line.
If you have ever run a minecraft bukkit server from the command line, you should know what I'm talking about.
Here's a picture of what I'm talking about if you still don't understand. Imagine this was in terminal, and ignore the scroll bars: http://cl.ly/1K0h1V0r0H3f3U3t3L22
Is there anyway to set the console to look like this without having to make your own program for it or having the screen reprint all the other info to fake that look?
I have not done this, but I believe something similar is possible with very little effort by using Node.js REPL. You can override the eval parameter to provide your own command processing.
It would not have the exact look you are wanting, but it will be an interactive prompt that you can utilize (more similar to a Windows command shell or a Linux shell).
If you want the exact look from your screenshot, I don't believe that there is any Node.js module that will help you. There are some that allow you to use colors in the console, and some basic highlighting (e.g. bold), but nothing that gives you complete control over the console screen.

Linux(Ubuntu) Terminal-how to view previous pages not visible anymore

When you scroll up, say to see a log, the first portion of it will not be visible since the terminal only supports a limited no. of lines. So if you want to scroll up and be able to see everything, at least a few pages up, how do you do it?
Use Shift+Page Up and Shift+Page Down.
Piping the output to a pager like the following is a better choice:
command | less
command | more
You can enable unlimited scroll back (or a huge amount if you want).
To do this, go to
File → Profile preferences → Scrolling [tab]
Then, check Unlimited, or set the number of lines desired. And of course, it only applies to the next typed lines.
Some tricks I use-
some terminal applications (gnome-terminal) allow you to increase the scroll-back buffer size
pipe output to a file:
command > file.log
pipe your command to less:
command | less
tail log and pipe to grep to reduce output
tail -f example.log | grep 'search text'
An alternative to screen is using tee to copy all output to a file while still printing it on the terminal:
yourcommand | tee output.txt
Try using the screen command, and set its scrollback buffer to a larger size.
screen has many other benefits and wonderful features.
If all you're doing is looking at a log, you could alternately use a pager such as less
If you want to scroll line by line, you can use
Control+Shift+Up/Down Arrows.
If you are using gnome-term (the default), then you can change your settings. Either set the no. of lines to unlimited, or to a much larger buffer size than the default.
Essentially seconding to #zerick's solution but if you're on gnome-terminal you can modify its config. See this.
If you are in tmux (can create multiple terminal sessions in a single terminal session, highly recommended), you can easily use your normal navigation keys to scroll around after you do Ctrl-b then [, for more details let's take a look at: How do I scroll in tmux?
None of these answer the original question. All answers are how to make new terminal windows (or current one) start behaving a certain way. The question is about how to see whats already scrolled away.
To answer this, each terminal session should have it's own "history" file (not to be confused with what command history is) containing all the stuff that relates to stdin/stdout displayed. I could be wrong but this may be different depending on the terminal emulator you use. Some just trash it when you close the window/ end the session.
I am trying to get this figured out myself so here is the more direct answer in a different thread.
https://unix.stackexchange.com/questions/145050/what-exactly-is-scrollback-and-scrollback-buffer
From what this tells me, I suspect best advice you can get is, for whatever terminal emulator you use, look for where it stores the scrollback buffer and that might be your only hope. It's what I am going to try right now. (and that is IF the session is currently still open, not closed terminal windows)

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