How to recover data from heavily damaged external hard drive?
How can I efficiently recover a permanently deleted folder at once?
bash: adduser: command not found on centOS I installed CentOS 5.5 on my VMWare 8 recently and I am trying to add a new user on the system. I am unable to add the user unless I use su - option. I believe it has to do something with path not set properly.  I updated the path and here is what it looks like  /usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/home/uone/bin:/sbin   I believe the command is in /sbin dir which is already a part of path. Can anyone suggest me what else I might be missing? I accidentally clicked reject on the suggested edit on this question(). I can't find the button to change it to Approve? How to install Skype 4.3? Note: The legacy Skype for Linux application (v4.*) is now discontinued and was removed from Canonical’s partner repositories, so this question and its answers are obsolete. Please refer to  of our .  Skype 4.3 is just released with considerable improvements. As a regular Skype user I want to use the latest Skype on my Ubuntu 14.04, but there is no updates from Update Manager. Even in Skype website only Skype 4.3 is available only for Ubuntu 12.04. Is there anyway to use this latest Skype on Ubuntu 14.04 or how much we have to wait for the update? Text processing - join every two lines with commas I have more than 1000 lines in a file. The file starts as follows (line numbers added):  Station Name Station Code A N DEV NAGAR ACND ABHAIPUR AHA ABOHAR ABS ABU ROAD ABR   I need to convert this to a file, with comma separated entries by joining every two lines. The final data should look like  Station Name,Station Code A N DEV NAGAR,ACND ABHAIPUR,AHA ABOHAR,ABS ABU ROAD,ABR ...   What I was trying was - trying to write a shell script and then echo them with comma in between. But I guess a simpler effective one-liner would do the job here may be in sed/awk.  Any ideas? If you have the ability to cast a spell without a spell slot, can you cast that spell using a spell slot? Seems that I just proved $2=4$. Solving $x^{x^{x^{.^{.^.}}}}=2\Rightarrow x^2=2\Rightarrow x=\sqrt 2$.  Solving $x^{x^{x^{.^{.^.}}}}=4\Rightarrow x^4=4\Rightarrow x=\sqrt 2$.  Therefore, $\sqrt 2^{\sqrt 2^{\sqrt 2^{.^{.^.}}}}=2$ and $\sqrt 2^{\sqrt 2^{\sqrt 2^{.^{.^.}}}}=4\Rightarrow\bf{2=4}$.  What's happening!? 100% confidence interval for mean Is it possible to apply the law of the iterated logarithm (e.g. ) to derive non-trivial (i.e. bounded) 100% confidence intervals for population averages?  An abstract () gives at least such hint. However, its first reference by Robbins () does not seem to cover such result, as pointed out in @whuber's comment.  Edit: After justified comments by @whuber, I reformulated the question. Uninstalling Ubuntu from Windows Dual Boot if I don't have Windows recovery CD I installed Ubuntu (I had already had Windows 8.1) from USB (I still have live Ubuntu on it). Is there a way I can uninstall Ubuntu in a way that my Windows will remain bootable? All the tutorials I have seen say that uninstalling ubuntu will delete GRUB also so I will need a Windows recovery CD to boot into it, but I don't have one. Is there a solution? What does "off of" mean? I have read a sentence from “Diary of a Wimpy Kid 4”:     The teachers have really been cracking down on kids copying off of each other this year.   How to understand "off of"? Please parse it. Is there a dominant gene for right-handedness? Has there been any definitive research about handedness being genetic? Also, why is right-handedness clearly dominant in humans? I'm interested in evolutionary theories, as well as any molecular explanation (if known). UK coastline shapefile? Why Doesn't the Adamantium Bone Covering Kill Wolverine? I've seen the  here before, as well as on many sites on the web.  I've also seen different info on what was covered.  I'm not a huge X-Men fan, but I do enjoy the characters and stories, so I know I'm probably missing out on a lot, and may have missed the obvious along the way because I didn't read a particular series or something like that.  I had a relative die from leukemia a few years ago and that reminded me of basic junior high science: that red and white blood cells are produced in the bone marrow and must be able to reach from the marrow into the blood vessels.  The leukemia my relative had was the kind where the "bad" cells would surround the marrow and prevent the new "good" blood cells from getting out to the rest of the body.  So just how much of Wolverine's skeleton is covered with Adamantium?  If it's the whole thing, there'd have to be openings for new red blood cells to get out if he is to remain alive.  I've never seen a reference to this issue, is it ever addressed?  That also raises another issue along the same line: Are hard to reach areas, such as ball and socket joints covered?  If not, then stress on other covered areas could be transferred to the weaker uncovered areas, which would lead to breakage there.  And if joints like that are covered, is there anything to say how it was done?  Are there openings or gaps in the Adamantium covering on his body?  Are there any references to any of these issues that deal with them? Use abbreviations for 1000+ score in linked posts I don't really enjoy the ragged view of linked posts:    This feature request is to use a format that suggested in ; something that matches the user-profile tags page in terms of the tally:    That is, use abbreviations for 1000+ (k for 1,000+, m for 1,000,000+, ...). How do I list all available shell builtin commands? We know bash supports number of  buitin commands  like:  $ type type cd help command type is a shell builtin cd is a shell builtin help is a shell builtin command is a shell builtin   I want to get list of all available shell builtin commands. How do I do that by command-line? When it's OK to omit "where?" Sequences or 'chains' of adjoint functors Suppose we have (some categories and some functors such that) $F_1$ is left adjoint to $G_1$, $G_1$ left adjoint to $F_2$, $F_2$ left adjoint to $G_2$. Will $F_1$ then be equal to $F_2$ (and $G_1$ to $G_2$)?  Or can there exist arbitrarily long 'chains' of adjoint functors that do not trivialize? How to deal a specific amount of damage using commands? I want to make a datapack where if you touch lime glass, you get damaged 2.5 hearts. I don't want the commands to work for just this specific value. Instead, I want to be able to specify the amount of damage. I can't use the instant damage effect because it's not controllable. I run a guest ubuntu 12.04 on a host ubuntu 12.04, with VirtualBox, and the guest is much, much slower than the host (ALT+TAB takes 4-5 secs). I had a look around and I found contradicting opinions on VirtualBox versus VMware (free); so I thought to keep the former.   Both systems are updated, I installed the additions on the guest and I evenly split memory and video memory (64MB) between guest and host. I am running a Toshiba m200 laptop with 4GB ram and shared video memory. The host bios does not include a configuration option for machine virtualization. I have 2 cpus and I can't give them both to the virtual machine.  Is there anything I overlooked that could solve my problem?  Feel free to ask for more info, and thank you for any help.  EDIT Idling with the system monitor open the (single) guest cpu never gets below 55% and could rise to 80 - 90% just by moving the mouse around. Opening Firefox will cause the system monitor to show cpu usage 100% in the guest, while the host shows that both cpus are evenly working around 60%.  My cpu is Intel® Core™2 Duo CPU T5450 @ 1.66GHz × 2.  If this is not a configuration problem, does it mean my machine is too weak for virtualization? I have 2 tables. One (domains) has domain ids, and domain names (dom_id, dom_url).  the other contains actual data, 2 of which columns require a TO and FROM domain names. So I have 2 columns rev_dom_from and rev_dom_for, both of which store the domain name id, from the domains table.  Simple.  Now I need to actually display both domain names on the webpage. I know how to display one or the other, via the LEFT JOIN domains ON reviews.rev_dom_for = domains.dom_url query, and then you echo out the dom_url, which would echo out the domain name in the rev_dom_for column.  But how would I make it echo out the 2nd domain name, in the dom_rev_from column? Where are packages stored installed with APT in Ubuntu 16.04?