Without updating update_history how can I ensure my text file will contain:  hello\ world john\ doe   That is how can I pass $greeting $name to a function or command as hello\ world john\ doe.    function update_history {   history=/tmp/hist   grep -qF "$1" "$history" \     || (combinations=$(echo "$1" | cat - $history) \         &amp;&amp; echo "$combinations" &gt; $history) }  greeting=hello\ world name=john\ doe  update_history "$greeting $name"
Or, an introductory guide to robust filename handling and other string passing in shell scripts.  I wrote a shell script which works well most of the time. But it chokes on some inputs (e.g. on some file names).  I encountered a problem such as the following:   I have a file name containing a space hello world, and it was treated as two separate files hello and world. I have an input line with two consecutive spaces and they shrank to one in the input. Leading and trailing whitespace disappears from input lines. Sometimes, when the input contains one of the characters \[*?, they are replaced by some text which is is actually the name of files. There is an apostrophe ' (or a double quote ") in the input and things got weird after that point. There is a backslash in the input (or: I am using Cygwin and some of my file names have Windows-style \ separators).   What is going on and how do I fix it?
Determinant of a $2\times 2$ block matrix I would like to know the proof for:  The determinant of the block matrix $$\begin{pmatrix} A &amp; B\\ C&amp; D\end{pmatrix}$$ equals $$(D-1) \det(A) + \det(A-BC) = (D+1) \det(A) - \det(A+BC)$$ when $A$ is a square matrix, $D$ is a scalar, $C$ is a row vector and $B$ is a column vector.  I appreciate your help. How to make a multiboot CD that will start a user-chosen ISO file I have many CD ISOs downloaded from the Internet. They are each about 100 MB in size and consist of repair/diagnostic programs and other tools. Some of them are Linux-based; others are based on DOS clones, like FreeDOS. I want to put all of the ISOs onto one bootable DVD, so that when I use the DVD, I will get a menu prompting me to select the ISO I want to boot. How can I do this? I've seen some rescue CDs that are combinations of other people's ISOs, but I have no idea how they were made.  Regarding bounty: I, a different person than the OP, have placed a bounty on this question for a solution that meets ALL of these criteria:  Is for DVDs (not flash drives!!!) Is free Works with any ISO file, regardless of original OS I see people say statement as question while speaking by raising their voice at the of it to mean it's a question.   For example consider followings.         You want to stay here? ==> Is used to mean "Do you want to stay here?"   You guys spoke to anyone? ==> Is used to mean "Did you guys speak to anyone?"      Are these really used by native speaker in casual speech? And can I write them in the same way while writing them as dialogue by putting them between quotes? Are there any special grammar rules for these kind of questions? Nielsen & Chuang Exercise 2.2 - “Matrix representations: example” Reproduced from Exercise 2.2 of Nielsen &amp; Chuang's Quantum Computation and Quantum Information (10th Anniversary Edition):     Suppose $V$ is a vector space with basis vectors $|0\rangle$ and $|1\rangle$, and $A$ is a linear operator from $V$ to $V$ such that $A|0\rangle = |1\rangle$ and $A|1\rangle = |0\rangle$. Give a matrix representation for $A$, with respect to the input basis $|0\rangle, |1\rangle$, and the output basis $|0\rangle, |1\rangle$. Find input and output bases which give rise to a different matrix representation of $A$.   Note: This question is part of a series attempting to provide worked solutions to the exercises provided in the above book. How do I split a string by a multi-character delimiter in C#? Why do I get compiler errors with this Java code?  1  public List&lt;? extends Foo&gt; getFoos() 2  { 3    List&lt;? extends Foo&gt; foos = new ArrayList&lt;? extends Foo&gt;(); 4    foos.add(new SubFoo()); 5    return foos; 6  }  Where 'SubFoo' is a concrete class that implements Foo, and Foo is an interface.  Errors I get with this code:   On Line 3: "Cannot instantiate ArrayList&lt;? extends Foo&gt;" On Line 4: "The method add(capture#1-of ? extends Foo) in the type List&lt;capture#1-of ? extends Foo&gt; is not applicable for the arguments (SubFoo)"   Update: Thanks to Jeff C, I can change Line 3 to say "new ArrayList&lt;Foo&gt;();".  But I'm still having the issue with Line 4. I am part of a “study team” that authored a paper. How do I list in in my CV? back commandbutton in jsf I have tried to map this simple object, but the uv mapping does not correspond to what i see in the textured object. It cuts the image a bit on top and a bit on the bottom of the faces. It does not fill the faces with the texture, even though i have mapped them correctly. Does anyone know what could be happening? Thanks in advance. What sort of waves are produced by tuning forks? Is it transverse, longitudinal or both? We often know tuning forks are used to to produce wave in various experiments that we do in lab. But the matter of concern is what sort of waves are produced by it? Is it transverse, longitudinal or both? How to increase difficulty in Dungeon World I've been GMing for a couple of sessions now and I'm still struggling at making encounters or situations more difficult. I will describe dangerous situations and encounters in fiction but the mechanics make it too easy for my players to succeed.  For instance no matter how big I describe the Troll, if the fighter of the party charges him and swing his sword, roll+2 for Hack and slash, he'll easily hit the troll. Almost 40% chance to hit without consequences. My reputation suddenly raised by 10k! Defining starred versions of commands (* macro) Finding the limit of $\frac {n}{\sqrt[n]{n!}}$ I had this question:    All 3 responses were rated at 1 when the bounty expired. Nothing got selected as the "best answer", and I can't even manually select an answer. How do you make HDDs and partitions mount at startup on Ubuntu?  I always keep my media and data files on separate partitions - one 2tb HDD and a 400 odd gig partition.  I have been trying to swap the default folder location for the home directory to my other drives.  It works when I change the /home/user_name/.config/user-dirs.dirs file to the directories I want, but only until I reboot the system. I am only assuming that the drives not mounting is the problem with it, but it would be helpful either way.  If any one knows another reason for why the directories change back to default each time that would be good also. I'm confused. Running Fedora Linux, lscpu yields:  Architecture:            i686 CPU op-mode(s):          32-bit, 64-bit ...   But when I try to install a 64-bit program (Chrome) I get error like:     Package /....x86_64.rpm has incompatible architecture x86_64. Valid architectures are ['i686', 'i586', 'i486', i386']   I'm less interested in being able to install Chrome and more interested in why lscpu says that my CPU can run in 64-bit mode; clearly this can't mean I can run 64-bit programs. Can anyone clarify? Seeking administrative boundaries for various countries? After learning about the  datasets I've working with the following layers, from the USA data   Country boundaries State boundaries County boundaries City boundaries ZipCode/Postcode boundaries   What I am trying to find is the equivalent (where appropriate) of the same data for various countries.  Is there any free administrative boundaries available as shapefiles for other countries? Non-Metrizable Topological Spaces Cannot authenticate without a password