So I just found out I can create log files of everything I do in screen (C-a H). Sounds like a nice way to keep track of potential goofs in a particular screen session. However, when I went to try it out the logfile is reported as being a binary file (and can't be viewed like a regular text as such). So am I missing something? A quick man page looksee and searching Google (and SO) turns up nothing about this.
So my question is: How do I generate plain text log files in screen?
Assuming the answer is "What a noob... how about you try making them? RTFM." my question becomes: How do I use less to view screen logfiles I've created (since less screenlog.0 does not work on a binary file)?
EDIT: So cat works fine but less complains that the file is binary... why?
SOLUTION: as jcomeau_ictx helpfully pointed out, you can view these logfiles fine with cat or more but with less you must add the -r flag less -r screenlog.0
I just found a screenlog.0 on the net; it is plain text, with some escape sequences. Just 'cat' the file, you should be able to view it just fine.
[after more checking]
Control-A H is what generates the screenlog on my system. And though 'cat' works, you'll miss a lot of data. Use 'more' instead of 'less' to interpolate the escape codes.
I found neither less nor more nor cat to be an ideal solution for viewing screenlog files. All "replay" some of the control character so that e.g. screen deletions as produced by "clear" (don't remember the corresponding control character) are beeing shown, hiding what has been cleared.
What i know works great is: use "view" or "vi", it just shows the control character in escaped notation. Probably any other text editor works, too (not tested).
-L logs to file,
tail -f 'logfilename' to monitor this file
Related
I am using Node.js to write to log files, using the colors module which I believe inserts control characters into strings, for coloring/text formatting which will display in a terminal application.
When I write to the terminal directly, it shows colors, but when I write to a .log file and then tail the log file with either Terminal.app or iterm2, it does not show colors/text formatting. Does anybody know why this is? My guess is that when you write to the log file the control characters don't get saved? In that way, when tailing they won't display at all?
Perhaps if I write to .txt file or some other type of file, the control characters will remain?
How does this work exactly? At some point the control characters are getting stripped or ignored and I am not sure how or when.
See this code.
It checks if the output is going to a terminal (by checking process.stdout.isTTY) or to somewhere else, like a file. If the latter, no color codes are outputted.
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/
I have a huge log file (25.3 million lines) with errors and I won't to search it without holding down the up button. How can you search this with vi? I've seen similar at directory levels but not particular files. At the moment I've searched a date e.g. /Tue 15 Jan
and navigated down but I'm not sure when problems may have began (only when noticed) so I need a general search.
My general idea from within the file would be /ORA-/!ORA-00020
meaning that I want to find those strings containing "ORA-" but ignoring those that are "ORA-00020". Any idea how this can be done viewing a particular file?
Thanks for any info
You do
grep -v "ORA\-00020" error.log > error2.log
then you search error2.log
I don't know the exactly way on vi, but we have kind of ways to get the result:
we can use cat/grep commands and write the answers in another file (so we have much smaller file) and then you can search in it, if it will be ok.
you can use vim instead vi and use TagList Vim Plugin.
Additional info at:
http://www.thegeekstuff.com/2009/04/ctags-taglist-vi-vim-editor-as-sourece-code-browser/
http://vim-taglist.sourceforge.net/faq.html
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)
Sometimes I work with a file that contains source code, columns, plain text, sometimes all 3. It looks great on the screen. However, when I send it to a printer, it comes out a mess: columns/tables are misalignment, code looks like a spaghetti, etc.
I use Vim (7.2). How do I reformat the file to please the printer?
Perhaps I should shorten the length of a line?
How do you send it to printer? Try :hardcopy command.
You can also lookup printing-related options printfont, printdevice, printoptions, etc.
See also printoptions and others on vimdoc.sourceforge.net
It's not a pure-Vim solution, but I've had good experiences with GNU a2ps for converting (relatively) poorly formatted text documents (a couple Project Gutenberg titles, to be specific) to a nice, printable pdf/postscript file.
If you aren't worried about having to have a one-step process with no intermediary between Vim and the printer, here is a fairly flexible strategy.
If you have a dark background in Vim with light foreground but would like to print black-on-white since white-on-black is great for terminals but not so great for printed media, try colorscheme shine. (Another nice colorscheme for this is Hemisu, which is superior to Shine for printing diffs.)
Use :TOhtml to convert the document to HTML.
Save the file and open it in your browser.
Open print preview from your browser and set up the window appropriately.
For example, I just printed a nearly 200 column file brought in from Vim this way, and it worked out fine (both in the sense of "well" and in the sense of "small print" :) because I was able to use Firefox's print preview to set the file to print in landscape mode.
Print the file from your browser.
I agree there is a problem. yim has 'formatoptions' to 'wrap' lines together the way you want and break lines at appropriate places ('linebreak', 'breakat') which would give you an elementary wysiwyg word-processing capability, except that it only works on the display and has no effect when sent off to print.