Comments on: Screen Command Examples: Get Control of Linux / Unix Terminal

By: sage

sage — Wed, 04 May 2011 07:28:07 +0000

thanks for this great article actually it helped me a lot to understand this easy and powerful unix command

By: Gaurav

Gaurav — Sat, 08 Jan 2011 23:36:55 +0000

Hi,

I want to group 10 unix commands in one shell script which while invoked can run these 10 jobs in parallel, as one job serves the input to the other.

So can I use “screen” command to open a new window each time running a job? and if yes then how should i handle the authentication as it need username and password at every login.

thanks in advance.

By: HakunX3

HakunX3 — Tue, 09 Nov 2010 15:22:48 +0000

Thank you for a great blog. I have a question.
How can we see exactly the command (name, arguments, etc) which is being handled by screen instead of screen ID? If so, I don’t have to attempt to attach into all ID to find expected handled command.

By: Jeremy Impson

Jeremy Impson — Mon, 09 Aug 2010 17:41:32 +0000

In general I recommend against starting screen like “screen ./unix-command”. When the unix-command exits, the controlling screen will also exit. This will prevent you from seeing any errors, warnings, or output messages. Instead, run “screen” by itself which will cause it to spawn a subshell prompt, then run “unix-command” in the subshell. I do this as my default behaviour so I don’t have to think about whether I need the screen to persist or not.

My logic is that since most things you want to run in screen are long-running tasks that you don’t want interrupted, it’s usually true that you want to see what messages it left on the terminal, especially if it crashed or was killed.

The downside of this approach is that you can’t start screen sessions programmatically (say, at boot). That hasn’t been a problem for me, but as a work around I suppose you could write a shell script that runs your command then blocks on input (“read X”), then run that script as the article originally describes.

By: Jim Plush

Jim Plush — Tue, 13 Jul 2010 16:07:02 +0000

you can also name the screen so when you’re doing screen -ls or screen -r you can use a simple name

screen -S jimtest

screen -r jimtest

By: Dave

Dave — Thu, 08 Jul 2010 02:49:24 +0000

So, is this isolated to a per user instance? If I log in as bob, then log into the same machine as sam, does sam get bob’s screen activity when doing screen -ls?

Also if I sudo to root, does root own the screen instance. If bob sudos to root, then sam logs in and sudos to root, could sam see the items that bob started after sudo’ing, or is it on a per sudo basis?

By: Lakshmanan

Lakshmanan — Wed, 07 Jul 2010 04:54:26 +0000

Hi,
There is another important usage of screen command, which is sharing a session between multiple users.
Here is the step to achieve that:

* The screen executable has to setuid
chmod u+s /usr/bin/screen
* Launch a screen session
screen
Type ctrl + a and : ( You will get a prompt at the bottom of the screen to type screen commands)
Type “multiuser on” ( We enabled multiuser session ).
Press ctrl + a and : again.
Type aclchg user5 -w “#” ( username is the name of the user to whom we have to share with. -w is to disable write permission to the user )

Now login as user5 and type
screen -x lakshmanan/

Now the user5 will be able to see what the user lakshmanan is doing in the screen.

By: RO

RO — Tue, 06 Jul 2010 12:20:15 +0000

A really huge advantage with using screen (or VNC as I more commonly do), is that when doing work that must not be interrupted, such as an installation or complex update, and your connection may be erratic, you can work from a screen session on a more reliable server, such as inside a corporate data center. That way, if your PC loses its connection, your work is not lost, and you do not face the tedious process of a backout/restart – instead, you just re-connect to your still-running screen session. That approach has saved me a lot of grief over the years in supporting important business applications.

By: Psychokiller

Psychokiller — Tue, 06 Jul 2010 10:41:28 +0000

Why not tmux instead?

http://tmux.sourceforge.net/

It might seem a clone at first, but definitely better after some time…