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Screen: Difference between revisions
→Screen commands
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== Basics == | == Basics == | ||
'''Screen''' usually does not exist | '''Screen''' usually does not exist; this <s>is the committee's</s> was a former committee's general position on screen due to the disastrous and/or hilarious situations which often result from new members' attempts to get it working. However, for the purpose of this tutorial, screen '''does''' exist, and this is how you use it. (Blame coconut for this defiance.) | ||
=== Omg, what's screen? === | === Omg, what's screen? === | ||
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=== Detaching and reattaching screen === | === Detaching and reattaching screen === | ||
One of the most popular features of screen is that it can keep you logged in even when you're offline. This means you can leave programs running or even stay on IRC even when you're not online. To this, you just detach from screen instead of exiting it. To detach from screen without exiting, use the following command: | |||
One of the most popular features of screen is that it can keep you logged in even when you're offline. This means you can leave programs running or even stay on IRC even when you're not online. When you "minimise" screen or make it invisible, it is called detaching it. | |||
To do this, you just detach from screen instead of exiting it. To detach from screen without exiting, use the following command: | |||
ctrl-a d | ctrl-a d | ||
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Later, you'll come back online and want to reattach to your screen session. To reattach a detached screen, use this command at the prompt: | Later, you'll come back online and want to reattach to your screen session. When you "maximise" screen or bring it back onto your terminal, this is known as attaching. To reattach a detached screen, use this command at the prompt: | ||
screen -dr | screen -dr | ||
The -d will detach any | The -d will detach any attached screens and -r will reattach your screen. | ||
If you have more than one screen session available, you will need to specify the screen id you wish to open. You'll be given a list of the currently available screens, so then you type: | If you have more than one screen session available, you will need to specify the screen id you wish to open. You'll be given a list of the currently available screens, so then you type: | ||
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followed by the id listed above of the screen you want to reattach to. | followed by the id listed above of the screen you want to reattach to. | ||
=== Moving windows === | |||
If are in a window, but want it to move it to another, just type these commands while attached to screen and in that window, and replace '''x''' with the destination you want: | |||
Ctrl + a | |||
: | |||
number x | |||
For example, if you are in window number 2, press '''Ctrl+a''', then type the colon symbol (''':'''), then '''number 4''', to move that window to window 4. | |||
=== Start and stop signals === | === Start and stop signals === | ||
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This should have you back in action very shortly. However, if your screen is frozen and you can't figure out why, try asking a member of [[Helpdesk]] and they should know the answer :) | This should have you back in action very shortly. However, if your screen is frozen and you can't figure out why, try asking a member of [[Helpdesk]] and they should know the answer :) | ||
=== Killing screen === | === Killing screen while attached === | ||
Often enough new members (and | Often enough new members (and often, experienced people) will make mistakes with screen that they can't fix. To kill screen altogether and start over, use: | ||
ctrl-a \ | ctrl-a \ | ||
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or even just type "exit" at the prompt. | or even just type "exit" at the prompt. | ||
=== | === Killing screen while detached === | ||
'''Warning''': using the ''kill'' command to do anything can be very dangerous if you don't know what you're doing. If you're unsure, reattach the screen you want to kill and follow the instructions above. | |||
If you have more than one screen session and you want to kill one of them, type "screen -dr" to get a list of the available screens (from the terminal which appears when you first log in to RedBrick). Note the '''number''' (also known as a process id, or pid) at the beginning of each screen name. This is the process number. Ensure you know which screen session is which. | |||
To terminate a session, use this command (''pid'' is the number of the session you want to kill) | |||
kill ''pid'' | |||
This will send the signal SIGTERM to the process, requesting its termination. | |||
If that fails and you want lil_cain to start complaining | |||
kill -9 ''pid'' | |||
This will send the signal SIGKILL to the process, terminating it immediately and with lots of blood. | |||
Then, to then get rid of the dead screen session, type | |||
screen -wipe | |||
== Screen Configuration == | |||
So after you've set up screen and have gotten used to it, you will probably want to configure it a little bit and the way to do this is by creating a ~/.screenrc | |||
To do this just | |||
nano ~/.screenrc | |||
Here's an example of a .screenrc that you may want to use: | |||
hardstatus alwayslastline | |||
hardstatus string '%{= kg}[ %{G}%H %{g}][%= %{= kw}%?%-Lw%?%{=b kR}(%{W}%n*%f %t%?(%u)%?%{=b kR})%{= kw}%?%+Lw%? %?%= %{g}][%{Y}%l%{g}]%{=b C}[ %d %M %c ]%{W}' | |||
deflogin off | |||
startup_message off | |||
screen -t irc 1 irssi | |||
screen -t Email/slrn 2 mutt -Z | |||
screen -t heys -L -l 3 | |||
Basically this only really does two things, sets a hardstatus (basically a line that contains some information) and makes it display only on the bottom line and also creates a few new windows. | |||
The new windows created are given names and optionally a number or command (or both). | |||
screen -t irc q irssi | |||
This will create screen window 1, give it the title "irc" and then run irssi when you start screen. | |||
deflogin off | |||
This sets windows logged out by default, which means that you won't have to "mesg n" windows to not receive heys | |||
startup_message off | |||
This turns the startup message thats displayed when you start a new screen session off. | |||
screen -t heys -L -l 3 | |||
Will create a logged in window specifically for heys. Handy. | |||
All this makes it very simple to restart all your processes if Redbrick ever crashes. | |||
With the above configuration file it will look something like this: | |||
[[Image:screenrc.jpg]] | |||
=== Reattaching Screen Automatically === | |||
So, you've made your screen, configured it, and you happily type screen -dr '''every time''' you login to RedBrick. But wouldn't it be nice if whenever you login your screen would reattach '''itself'''??? It can be done :D | |||
Simply use your favorite text editor to edit your ~/.zlogin if you're using zsh (if you haven't changed your login shell, this is the one you're using) or ~/.bash_login if you're using bash and put the following in it | |||
screen -dr | |||
That should do the job. It'll try to reattach a screen whenever you login on any redbrick server | |||
* Please note, if this in fact, does not work, you can edit it out by using winSCP and editing the file using it. | |||
== Useful links == | |||
If you'd like to learn more about the program, a long list of screen commands can be found here: http://www.linuxdevcenter.com/linux/cmd/cmd.csp?path=s/screen | If you'd like to learn more about the program, a long list of screen commands can be found here: http://www.linuxdevcenter.com/linux/cmd/cmd.csp?path=s/screen | ||
Help edited a screenrc: http://www.debian-administration.org/articles/560 | |||
A starting guide to screen: http://magazine.redhat.com/2007/09/27/a-guide-to-gnu-screen/ | |||
The Gentoo wiki article on screen (quite in depth) : http://www.gentoo-wiki.info/Screen | |||
[[Category:Helpdesk]] | [[Category:Helpdesk]] | ||