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? [maze@eonwe]~% ls -al /proc/10848/exe lrwxrwxrwx. 1 maze maze 0 Apr 27 21:48 /proc/10848/exe -> /usr/bin/bash (deleted) [maze@eonwe]~% /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 <a...@deuxchevaux.org> 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 | a...@deuxchevaux.org > (Mail) > X See http://www.nonhtmlmail.org/campaign.html | a...@noone.org > (Mail+Jabber) > / \ I love long mails: http://email.is-not-s.ms/ | http://noone.org/abe/ > (Web) >
