Re: Using 'stuff' to send characters from one account to a second account's session

[Chris Jones]

On Mon, Sep 24, 2012 at 01:45:53PM EDT, Lars Noodén wrote:

[..]

> Yes, screen -ls works from both accounts to detect the first user's
> session.  So it is proof that multiuser is working.  This works from
> the second account to detect the first user's session:
> 
>       screen -S user1/myscrn -ls

Hi, Lars,

I decided to take a closer look and this is what I see:

I did the following:

| % screen -S myscreen
| % 
:multiuser on
| % 
 addacl user2
| % 
 aclchg user2 +rwx '$#'

Then logged on as user2, from an xterm:

| % screen -S /user1/myscreen -ls
| There is a screen on:
|       3273.myscreen   (Private)
| 1 Socket in /tmp/screens/S-user1.

The session is listed.. not sure what '(Private)' refers to..?

But then I have a problem with permissions:

| % screen -S user1/myscreen stuff 'ls
'
| Cannot opendir /tmp/screens/S-user1: Permission denied

So, it looks like user2 finds user1's session and tries to write to the
socket, but is not allowed to do so.

If I change the permissions manually, it complains that the socket
directory permissions must be 700:

| % sudo chmod +rwx /tmp/screens/S-user1
| % screen -S user1/myscreen stuff 'ls
'
| Directory /tmp/screens/S-user1 must have mode 700

And if I change the ownership of /tmp/screens/S-user1 to user2, it
complains that user1 does not own the socket..

| % sudo chown user2.user2 /tmp/screens/S-user1
| % screen -S user1/myscreen stuff 'ls
'
| user1 is not the owner of /tmp/screens/S-vtest.

I also tried running the command as the superuser, or prefixing it with
sudo.. but then I get the 'No screen session found' error..

| % screen -v
| Screen version 4.01.00devel (GNUa6eea7b) 2-May-06

.. which somehow does not look right.. the program's timestamp goes back
to december 2009.. seems to be a git repos version dating back to about
that time..

Rather than a bug, I have a feeling I'm not doing this correctly..
probably leaving something out.. Didn't see much in the screen user
manual that helps.

CJ

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