I want to create a new command to set the column colour, but it's causing the following error:  ! Undefined control sequence. \redcolumn -&gt;\columncolor                            {red} l.10 A &amp; B            \\   I don't know if it's because I'm calling a command with a parameter or because of where I'm trying to call the new command, but here's the source code:  \documentclass[letterpaper,20pt]{extarticle} \usepackage[table,xcdraw]{xcolor} \newcommand{\redcolumn}{\columncolor{red}} \begin{document} \begin{tabular}{l &gt;{\columncolor{red}}l} A &amp; B \\ \end{tabular}  \begin{tabular}{l &gt;{\redcolumn}l} A &amp; B \\ \end{tabular}  \end{document}   The first tabular uses \columncolor, and it works. The second uses my new command, and it fails. How have I misunderstood \newcommand?
I'm trying to create a command, which calls on an environment, which defines a custom column definition with one argument using \newcolumntype, and defines a second command, containing parameters for a table column.  Then, still within the first command, I begin the tabular environment and call the custom column, with the second command as its argument. I always get an undefined control sequence error, though. Any thoughts on why that might be?  I'm sure that was clear as mud, but I've cut it down to a minimal example, which follows:  \documentclass{article} \usepackage{array} \usepackage[table,dvipsnames]{xcolor} \usepackage{colortbl}  \newenvironment{tablecolor}{     \newcommand{\tlight}{\columncolor{SkyBlue!30}\color{black}}     \newcolumntype{C}[1]{&gt;{##1}c} }{}  \newcommand{\tablegoals}{ \begin{tablecolor} \begin{tabular}{l|C{\tlight}} Goal 7  &amp; \\ \end{tabular} \end{tablecolor} }  \begin{document}     \tablegoals \end{document}     Here's my second attempt. Different approach, same undefined control sequence error with \columncolor.  \documentclass{article} \usepackage{array} \usepackage[table,dvipsnames]{xcolor} \usepackage{colortbl} \usepackage{ifthen}  \newenvironment{tablecolor}{     \newcolumntype{C}[1]{&gt;{         \ifthenelse{\equal{dark}{##1}}{             \columncolor{Cyan}\color{white}             }{             \columncolor{SkyBlue!30}\color{black}         }     }c} }{ }  \newcommand{\tablegoals}[1]{     \begin{tablecolor}         \begin{tabular}{l|C{dark}}             Goal 7  &amp;   #1         \end{tabular}     \end{tablecolor} }  \begin{document}     \tablegoals{Check mark} \end{document}
I have a bunch of external and internal HDDs that I use on a Linux system. I only have Linux systems, so using a Linux file-system would only make sense, right? However I'm currently using NTFS everywhere, because it gives me the most usable space out of HDDs.  I would like to switch to Linux file-systems now though, mostly because of permissions and compability (e.g. I can't get my LUKS encrypted NTFS partition to resize under Linux, keeps telling me to chkdsk under Windows).  However when I formatted those HDDs I tried out a bunch of different filesystems and every Linux filesystem, even ext2 which as far as I know has no journaling, used a lot of space for itself. I don't recall exact values, but it was over 100GB that NTFS got me more on a 2TB HDD, which is a lot.  So my question is: Is there a way to make ext-filesystems use less space for themselves? Or is there another filesystem (I've tried ext2, ext3, ext4, NTFS and vfat - None of them came even close to the usable space NTFS offered me) with perfect Linux support and great usable space?  I'd love to hear about how and why filesystems (especially ext2 which has no journaling) use that much more space than NTFS and I don't know where else to ask. I'd mostly prefer a way to use ext4 without journaling and anything else that uses up this much space, if that's possible. Evaluating the indefinite integral $ \int \sqrt{\tan x} ~ \mathrm{d}{x}. $ I have been having extreme difficulties with this integral. I would appreciate any and all help. $$ \int \sqrt{\tan x} ~ \mathrm{d}{x}. $$ What is the "Wanna Cry" ransomware's possible impact on Linux users? It's just come to light that there's a $300 ransom you have to pay because ransomware targeting Microsoft Windows has encrypted your data. What steps do Linux users need to protect from this if for example they are using wine?  This ransomware is widely reported to be based on a tool developed by the NSA to hack into computers. The NSA tool was used by a hacker group called the Shadow Brokers. The code can be found in .  Microsoft released a patch (MS17-010) against this vulnerability on March 14, 2017. The mass infection is reported to have begun spreading on April 14th. This is discussed .  As I haven't booted Windows 8.1 in 6 to 8 weeks, can I apply this patch from Ubuntu without booting Windows first? (After research it may be possible ClamAV could report the vulnerability from the Linux side looking into Windows partition but it's unlikely it could apply the patch. The best method would be to reboot into Windows and apply patch MS17-010.)  Individuals and small companies who subscribe to Microsoft Automatic Updates are uninfected. Larger organizations who delay apply patches as they are tested against organization intranets are more likely to be infected.  On May 13, 2017, Microsoft took the extraordinary step of releasing a patch for Windows XP which has been unsupported for 3 years.  No word if wine is doing anything about a security update. It was reported in a comment below that Linux can be infected too when users run .  An  registered a domain name that acted as a kill-switch to the ransomware. I presume the non-existent domain was used by the hackers on their private intranet so they didn't infect themselves.  Next time they will be smarter so don't rely on this current kill-switch. Installing the Microsoft patch, which prevents exploiting a vulnerability in the SMBv1 protocol, is the best method.  On May 14, 2017 Red Hat Linux said they are not affected by "Wanna Cry" ransomware. This might mislead Ubuntu users along with Red Hat, CentOS, ArchLinux and Fedora users. Red Hat supports wine which answers below confirm can be effected. In essence Ubuntu and other Linux distro users googling this issue might be mislead by the Red Hat Linux Support answer .  May 15, 2017 Update. Over the last 48 hours Microsoft released patches called KB4012598 for  to protect against "Wanna Cry" ransomware. These Windows versions are no longer on automatic updates. Although I applied security update MS17-010 on my Windows 8.1 platform yesterday, my old Vista Laptop still needs patch KB4012598 downloaded and manually applied.       Moderator note: This question is not off topic - it asks about whether or not any Linux users need to do any steps for protecting against the risk.      It is perfectly on topic here, because it's relevant to Linux (which Ubuntu is), and it's also relevant for Ubuntu users running Wine or similar compatibility layers, or even VMs on their Ubuntu Linux machines. How to disable grub menu at boot time in Ubuntu 20.04? Use nmcli to modify VPN password? With nmcli, I can modify VPN data like this:  nmcli con modify myvpn vpn.data 'refuse-pap = yes, user = xxx'   So I'm wondering if I can set password this way as well? The bounty I offered on  is now in its grace period and the information box tells me:     you must award this bounty as soon as possible   But there are no answers - what do I do? Why is my multimeter stopping device from booting when measuring current? I am using a BK Precision 2709B multimeter and attempting to measure the current of a device that runs off of a ~3.7V battery. The device boots up, initializes and then goes into its lower power state. If I use the 10A setting, my device boots up just fine but I need to measure uA or mA. When I attempt to use the mA setting, the device attempts to boot and then continuously reboots. Its not able to finish its initialization process before it cuts off. The current reading on the meter is ~30mA before the device cuts off and attempts to boot up again. The meter says 400mA max, so it doesn't seem like it is over the maximum allowed current for the mA setting. Is there anything I can do to get past the initialization so I can measure the lower power state? From , page 209:     Dividends   Dividends are income paid by investments. Both bond funds   and stocks can  pay dividends. Bond fund dividends (the interest paid   by the individual  bonds in a fund) tend to be higher (as a percentage   of the amount you have  invested in a fund). When a dividend   distribution is made, you can receive  it as cash (which is good if   you need money to live on) or reinvest it into  more shares in the   fund. In either case, the share price of the fund drops to  offset the   payout. So if you’re hoping to strike it rich by buying into a bunch    of funds just before their dividends are paid, don’t bother. You’ll   just end up  paying more in income taxes.    It is talking about mutual funds.   I've never played with stocks.  However, I would like to know more about it.  Does the bold text imply the stock price will drop because of a company giving out a dividend? I have heard that one ought to turn the pedals at 90rpm. However, I do so much slower, especially while standing, and would like to understand the argument behind this number (or any other number). So:  What is the optimal cadence of a cyclist. Why? Does it depend on the terrain? Does it depend if the rider is sitting or standing upright? What are some possible consequences of deviating too much from the proposed number?  Possible duplicate of , but I didn't find there the "whys" except for "it will grind your knees." However, I find riding upright with slow cadance no more demanding than walking up a hill with a backpack. Python metaheuristic packages Why did the Ministry of Magic choose an ax for carrying out a death sentence? How do you empty the buffers and cache on a Linux system? Prior to doing some benchmarking work how would one free up the memory (RAM) that the Linux Kernel is consuming for its buffers and cache?    Note that this is mostly useful for benchmarking. Emptying the buffers and cache reduces performance! If you're here because you thought that freeing buffers and cache was a positive thing, go and read . The short story: free memory is unused memory is wasted memory. FTP client on windows that save session password in encrypted text Filezilla or WinSCP save password in plain text which is unsecured on public machines. Is there any FTP client can save and encrypt password so that people using it only can access to FTP but not able to see password? Thanks! Visualforce Date formatting Using v2.73, cycles and a very simple scene: an array of cubes, no big deal.   If I set the shader's material to transparent, the cubes in the foreground do become transparent but those far away in the back do not disappear completely and this strange dark things appear (visible in rendered mode and in final renders)    I've played with the clipping distance on the viewport and camera, but I can't figure out how to make those ghosts go away... Don't automatically edit the post to insert "possible duplicate" links When a question is closed as a duplicate, its body is edited to auto-insert the link to that duplicate. I think there are a couple problems with that:   If the question is reopened, the auto-generated insert isn't automatically removed. It allows the poster (or anyone else) to roll back the post and protest the closure by reverting the automatic edit.    I propose that the links to the duplicate(s) are moved into a separate "header" field above the post instead of being edited into the body of the question. That way it could be removed or hidden if the question is reopened and it could not be edited or reverted without reopening the question.   There is some potential for loss of functionality there, since right now it is possible to edit the post to either include additional related links or remove obsolete/incorrect ones. That could be addressed by making the "duplicate field" editable at a certain reputation level (10k?) and enabling others to suggest edits for it that'd go through the usual approval/rejection process.  Thoughts? Can an LC oscillator be used to generate visible light? The LC oscillator is most commonly used to generate radio waves for practical use and the frequency $\omega$ of the LC oscillator equals that of the electromagnetic wave so produced. So, can they in principle be used to emit visible light?  The frequency of visible light is on the order of a few hundred terahertz, and the frequency of an LC oscillator is   $$\omega = \frac{1}{\sqrt{LC}}$$  I admit, the  product $LC$ does become very small (on the order of $10^{-30}$) when the numbers are plugged in, but making an inductor and a capacitor with small values isn't difficult, is it? How can I use variables in the LHS and RHS of a sed substitution? I want to do:  cat update_via_sed.sh | sed 's/old_name/new_name/' &gt; new_update_via_sed.sh   in my program.  But I want to use variables, e.g.  old_run='old_name_952' new_run='old_name_953'   I have tried using them but the substitution doesn't happen (no error). I have tried:  cat update_via_sed.sh | sed 's/old_run/new_run/' cat update_via_sed.sh | sed 's/$old_run/$new_run/' cat update_via_sed.sh | sed 's/${old_run}/${new_run}/' Words with different meanings in American and British English This is similar to , but not quite the same.  There are quite a few words which have totally different meanings in American and British English and which are likely to cause confusion when heard by non-local speakers.  What are they?  We are looking for the same word with different meanings (for example jumper), and not words which are different between the two dialects (for example truck and lorry). At which moment does the 'Surprised' state disappear?