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Re: [screen-devel] GNU Screen v.4.2.0
From: |
Maciej Żenczykowski |
Subject: |
Re: [screen-devel] GNU Screen v.4.2.0 |
Date: |
Sun, 27 Apr 2014 21:58:51 -0700 |
Curious I just reinstalled bash on my fedora 20 x86_64 system.
$ uname -a
Linux eonwe.lan 3.13.10-200.1mz.fc20.x86_64 #1 SMP Sat Apr 26 01:19:02
PDT 2014 x86_64 x86_64 x86_64 GNU/Linux
$ ls -al /proc/$$/exe
lrwxrwxrwx. 1 maze maze 0 Apr 27 21:48 /proc/10848/exe ->
/usr/bin/bash (deleted)
$ /proc/$$/exe --version
GNU bash, version 4.2.47(1)-release (x86_64-redhat-linux-gnu)
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
And as you can see I can still run the old marked deleted binary.
Maybe the problem is zsh?
address@hidden ls -al /proc/10848/exe
lrwxrwxrwx. 1 maze maze 0 Apr 27 21:48 /proc/10848/exe ->
/usr/bin/bash (deleted)
address@hidden /proc/10848/exe --version
GNU bash, version 4.2.47(1)-release (x86_64-redhat-linux-gnu)
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Hmm, not zsh.
I think it's related to some sort of permission dropping or
namespaceing or sandboxing screen is doing.
Since it fails for SCREEN:
$ ps auxww | egrep SCREEN
maze 11080 0.0 0.0 130348 1460 ? Ss 21:54 0:00 SCREEN
$ ls -al /proc/11080/exe
ls: cannot read symbolic link /proc/11080/exe: Permission denied
lrwxrwxrwx. 1 root root 0 Apr 27 21:54 /proc/11080/exe
$ /proc/11080/exe -ls
-bash: /proc/11080/exe: Permission denied
$ sudo su -
# ls -al /proc/11080/exe
lrwxrwxrwx. 1 root root 0 Apr 27 21:54 /proc/11080/exe -> /usr/bin/screen
# ls -al /usr/bin/screen
-rwxr-sr-x. 1 root screen 487416 Apr 8 07:10 /usr/bin/screen
# /proc/11080/exe -ls
No Sockets found in /var/run/screen/S-root.
So probably the SGID 'screen' bit is screwing it up for non-root users.
But not sure why even root didn't work for you.
On Sun, Apr 27, 2014 at 7:03 PM, Axel Beckert <address@hidden> wrote:
> Hi,
>
> On Fri, Apr 25, 2014 at 10:08:32PM +0200, Axel Beckert wrote:
>> > Also people wanting to attach to older session can use a workaround:
>> > $ ps a | grep SCREEN
>> > $ /proc/$pid_from_above/exe -r
>> > to reattach
>>
>> Yes. I'm somehow annoyed that I didn't have that idea two years ago.
>> :-) May have been easier than patching or my first attempt with saving
>> the old /usr/bin/screen somewhere under /tmp/.
>>
>> Then again that's said to just work on Linux and maybe FreeBSD with
>> Linux compatibility mode...
>
> Tried that between 4.2.0 and 4.2.1 -- doesn't work on Linux (anymore),
> neither as user nor as root:
>
> $ /proc/17773/exe -r
> zsh: permission denied: /proc/17773/exe
> # /proc/17773/exe -ls
> zsh: permission denied: /proc/17773/exe
>
> :-(
>
> So I'll likely have to extend the according patch to also try to talk
> with a 4.1.0/4.2.0 screen.
>
> Kind regards, Axel
> --
> /~\ Plain Text Ribbon Campaign | Axel Beckert
> \ / Say No to HTML in E-Mail and News | address@hidden (Mail)
> X See http://www.nonhtmlmail.org/campaign.html | address@hidden
> (Mail+Jabber)
> / \ I love long mails: http://email.is-not-s.ms/ | http://noone.org/abe/
> (Web)
>
- Re: [screen-devel] GNU Screen v.4.2.0, (continued)
- Re: [screen-devel] GNU Screen v.4.2.0, Jeroen Roovers, 2014/04/17
- Re: [screen-devel] GNU Screen v.4.2.0, Jürgen Weigert, 2014/04/17
- Re: [screen-devel] GNU Screen v.4.2.0, Jürgen Weigert, 2014/04/17
- Re: [screen-devel] GNU Screen v.4.2.0, Amadeusz Sławiński, 2014/04/18
- Re: [screen-devel] GNU Screen v.4.2.0, Axel Beckert, 2014/04/18
- Re: [screen-devel] GNU Screen v.4.2.0, Amadeusz Sławiński, 2014/04/25
- Re: [screen-devel] GNU Screen v.4.2.0, Axel Beckert, 2014/04/25
- Re: [screen-devel] GNU Screen v.4.2.0, Amadeusz Sławiński, 2014/04/25
- Re: [screen-devel] GNU Screen v.4.2.0, Axel Beckert, 2014/04/25
- Re: [screen-devel] GNU Screen v.4.2.0, Axel Beckert, 2014/04/27
- Re: [screen-devel] GNU Screen v.4.2.0,
Maciej Żenczykowski <=
- Re: [screen-devel] GNU Screen v.4.2.0, Axel Beckert, 2014/04/28
- Re: [screen-devel] GNU Screen v.4.2.0, Axel Beckert, 2014/04/28
- Re: [screen-devel] GNU Screen v.4.2.0, Jeroen Roovers, 2014/04/18
- Re: [screen-devel] GNU Screen v.4.2.0, Jim Mahood, 2014/04/18
- Re: [screen-devel] GNU Screen v.4.2.0, Amadeusz Sławiński, 2014/04/18
- Re: [screen-devel] GNU Screen v.4.2.0, Jürgen Weigert, 2014/04/18
- Re: [screen-devel] GNU Screen v.4.2.0, Amadeusz Sławiński, 2014/04/22
- [screen-devel] Remarks on the patch for long login names (was: Re: GNU Screen v.4.2.0), Axel Beckert, 2014/04/22
- Re: [screen-devel] Remarks on the patch for long login names (was: Re: GNU Screen v.4.2.0), Amadeusz Sławiński, 2014/04/22
- Re: [screen-devel] Remarks on the patch for long login names (was: Re: GNU Screen v.4.2.0), Axel Beckert, 2014/04/22