Unix & Linux Weekly Newsletter - Tuesday, September 30, 2014

Top new questions this week: What does env x='() { :;}; command' bash do and why is it insecure? There is apparently a vulnerability (CVE-2014-6271) in bash: https://securityblog.redhat.com/2014/09/24/bash-specially-crafted-environment-variables-code-injection-attack/ I am trying to figure out … / bash / shellshock / vulnerability   asked by jippie 155 votes answered by Chris Down 135 votes When was the shellshock (CVE-2014-6271/7169) bug introduced, and what is the patch that fully fixes it? Some context about the bug: CVE-2014-6271 Bash supports exporting not just shell variables, but also shell functions to other bash instances, via the process environment to (indirect) child … / bash / security / shellshock   asked by Deer Hunter 79 votes answered by Stéphane Chazelas 145 votes how can shellshock be exploited over SSH? Apparently, the shellshock Bash exploit CVE-2014-6271 can be exploited over the network via SSH. I can imagine how the exploit would work via Apache/CGI, but I cannot imagine how that would work over … / bash / ssh / shellshock   asked by Martin Vegter 42 votes answered by Patrick 55 votes Why did powering down my machine after a bad `rm` save my files? Classical situation: I ran a bad rm and realized immediately afterwards that I had removed the wrong files. (Nothing critical and I had tolerably recent backups, but still annoying.) Knowing that … / linux-kernel / data-recovery / rm / virtual-memory / journaling   asked by a3nm 28 votes answered by Patrick 20 votes How to efficiently generate large, uniformly distributed, random integers in bash? I have been wondering what would be the best way to get good randomness in bash, i.e., what would be a procedure to get a random positive integer between MIN and MAX such that The range can be … / bash / shell-script / command-line   asked by Malte Skoruppa 16 votes answered by Malte Skoruppa 1 vote Do we have more history for cd? cd - can move to the last visited directory. Can we visit more history other than the last one? / bash / shell / zsh / cd   asked by Tim 14 votes answered by Ramesh 17 votes Why does "ls | wc -l" show the correct number of files in current directory? Trying to count number of files in current directory, I found ls -1 | wc -l, which means: send the list of files (where every filename is printed in a new line) to the input of wc, where -l will count … / ls / wc   asked by Derp 14 votes answered by glenn jackman 28 votes Greatest hits from previous weeks: Is CentOS exactly the same as RHEL? I'm sure this question has been asked again and again elsewhere (I did not find anything specific to CentOS vs RHEL in SE), but I would still like to ask and confirm a few specific points. I am well … / centos / rhel   asked by Oxwivi 35 votes answered by Gilles 18 votes Getting tmux to copy a buffer to the clipboard I am trying to figure out a decent way to copy what I have in a tmux buffer into my clipboard. I have tried a couple of different things like bind-key p select-pane -t 2 \; split-window 'xsel -i … / keyboard-shortcuts / tmux / clipboard / copy-paste / xclip   asked by Digital Powers 40 votes answered by Gilles 15 votes Can you answer these? Shifting GNOME 3 top-left hot corner to left screen edge I would like to trigger the visualization of the GNOME3 Activities Panel by moving the mouse pointer to the left edge of the screen, instead of using the top-left screen corner. I have seen … / gnome3 / gnome-shell   asked by lucam 2 votes How to use chroot'd desktop environment on Android with external display, mouse and keyboard? I have a chroot'd Arch Linux environment set up on my Android phone (a OnePlus One) and I would like to connect it to a monitor (directly or with use of some sort of passthrough/adapter eg. Raspberry … / arch-linux / android / chroot / desktop-environment   asked by jackos2500 2 votes How to find IP of the KVM Virtual Machine from Host system? My KVM VMs are connected using MaCVTAP connection VM network Interfaces. I have to manually go into the VM to find the IP address. The VM interface doesn't ping to the host interface as the source … / linux / kvm   asked by Bhavik 2 votes

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