Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I was running scripts overnight from the command line (inside Screen on a Linux EC2 instance) and some errors that I was not tracking occurred. I want to "scroll up" or view more of the history in Screen, but I cannot seem to find any commands that will work.

I need to see the onscreen output "further up" than I can on my current screen. CTRL + a is supposed to put me into scroll mode inside Screen, but it's not working.

share|improve this question

migrated from stackoverflow.com Jun 28 '11 at 20:59

This question came from our site for professional and enthusiast programmers.

    
history | less, more? Or you are asking how to keep more history? – khachik Jun 28 '11 at 19:47
    
history will keep only commands have been fired in shell. He is more asking about logging sort of stuff – Rahul Jun 28 '11 at 19:49
    
<Shift> + <PgUp> is the only option. And it has some limit as well (at most last 500 lines, I guess). – ssapkota Jun 28 '11 at 19:51
    
I need to see the onscreen output "further up" than I can on my current screen. CTRL + a is supposed to put me into scroll mode inside Screen, but it's not working for me. – T. Brian Jones Jun 28 '11 at 19:52
1  
Just Ctrl-a is screen's escape. The whole key sequence to enter scrollback mode would be Ctrl-a [, as opyate says. Ctrl-a ESC also works for me, I don't remember which one is standard / commonly used. – ninjalj Jun 28 '11 at 20:01
up vote 15 down vote accepted

When you start screen you can specify the size of the scrollback buffer with -h, so you can increase it from the default of 100 lines. However, with a currently running screen, once the data has left the buffer, it is gone.

share|improve this answer

Assuming you haven't overriden your escape sequence, you can press Ctrl-a [ to go into scrollback mode, then use the usual Page-UP/Page-DOWN or Ctrl-b/Ctrl-f to go up and down.

From the Gentoo wiki on Screen usage

share|improve this answer
2  
and ESC to exit scrollback mode, IIRC – ninjalj Jun 28 '11 at 19:58
    
now the gentoo wiki is: wiki.gentoo.org/wiki/Screen – Rmatt Nov 8 '14 at 16:11
    
also see this post for how to (sort of) get scrolling with the mouse working. The post name says its for tmux but it also covers screen – Jonny Leeds Feb 25 '15 at 14:54

You can also run your commands in the script command which will log the output to disk. Or you can: command 2>&1 | tee /tmp/cmd.out to log the output for future investigation in you wanted a (practically) infinite sized output history.

share|improve this answer
    
this is what I ended up using for my task. Works great. Thanks. – T. Brian Jones Jun 28 '11 at 21:59

Depending on what terminal program you are using, you can usually change the Scrolling Buffer under Settings. I know for xterm you have to enable Scrolling first, then you can set the buffer to infinite.

Your best bet however for logging scripts would be to Re-direct the standard output to a file:

ScriptName >> OutputFile.txt

Doing it this way you can scroll and search freely as well as keep a record (i.e. in case your computer crashes).

EDIT: This is close to the piping solution above, however redirecting standard input can be useful in other instances as well:

grep linux stackoverflow.txt > linuxquestions.txt

or

cat linuxquestions.txt | grep buffersize > bufferquestions.txt
share|improve this answer
    
Do note that screen(1) doesn't allow terminal scrolling. That's both one of its main features and one of its main drawbacks. – sarnold Jun 28 '11 at 20:59

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .