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  • Regarding Shell variable

    - by arav
    I need to call another shell script testarg.sh within my main script. This script testarg.sh has arguments ARG1 ,ARG2, ARG3. I need to call up the below way ./testarg.sh -ARG1 -ARG2 -ARG3 ARG1 and ARG3 argument Variables are mandatory ones. If its not passed to the main script then i quit. ARG2 is an optional one. If the ARG2 variable is not set with value or it's not defined then i need not pass it from main script.So i need to call up the below way ./testarg.sh -ARG1 -ARG3 If the value exist for the ARG2 Varibale then i need to call the below way ./testarg.sh -ARG1 -ARG2 -ARG3 Do i need to have a if else statement for checking the ARG2 variable is empty or null. Is there any other way to do it.

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  • Confusion in bind call in socket programming

    - by Tarun
    i was learning socket programming in unix using c/c++. I am confused with one function call bind(params..). Actually it takes the adreess structure "sockaddr_in" and we can create the structure in the following way sockaddr_in.*** = somthing.. sockaddr_in..s_addr htonl(INADDR_ANY) **Passing INADDR_ANY will alow to bind all local addresses** My question is , why do we need to use "INADDR_ANY" ? In my knowledge every machine can has only one unique IP Address. In this way there is only one address associated with the machien. Thye bind call should directly bind the socket to the single available address. Please explain what are the different scenarios and why is it so?

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  • FDs not closed in FUSE filesystem

    - by cor
    Hi, I have a problem while implementing a fuse filesystem in python. for now i just have a proxy filesystem, exactly like a mount --bind would be. But, any file created, opened, or read on my filesystem is not released (the corresponding FD is not closed) Here is an example : yume% ./ProxyFs.py `pwd`/test yume% cd test yume% ls mdr yume% echo test test yume% ls mdr test yume% ps auxwww | grep python cor 22822 0.0 0.0 43596 4696 ? Ssl 12:57 0:00 python ./ProxyFs.py /home/cor/esl/proxyfs/test cor 22873 0.0 0.0 6352 812 pts/1 S+ 12:58 0:00 grep python yume% ls -l /proc/22822/fd total 0 lrwx------ 1 cor cor 64 2010-05-27 12:58 0 - /dev/null lrwx------ 1 cor cor 64 2010-05-27 12:58 1 - /dev/null lrwx------ 1 cor cor 64 2010-05-27 12:58 2 - /dev/null lrwx------ 1 cor cor 64 2010-05-27 12:58 3 - /dev/fuse l-wx------ 1 cor cor 64 2010-05-27 12:58 4 - /home/cor/test/test yume% Does anyone have a solution to actually really close the fds of the file I use in my fs ? I'm pretty sure it's a mistake in the implementation of the open, read, write hooks but i'm stucked... Let me know if you need more details ! Thanks a lot Cor

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  • Regarding PID Shell Script

    - by arav
    I am calling another shell script testarg.sh within my main script. the logfiles of testarg.sh are stored in $CUSTLOGS in the below format testarg.DDMONYY.PID.log example: testarg.09Jun10.21165.log In the main script after the testarg process gets completed i need to grep the log file for the text "ERROR" and "COMPLETED SUCCESSFULLY". How do i get the PID of the process and combine with DDMONYY for grepping. Also i need to check whether file exists before grepping $CUSTBIN/testarg.sh $CUSTBIN/testarg.sh rc=$? if [ $rc -ne 0 ]; then return $CODE_WARN fi

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  • Binding on a port with netpipes/netcat

    - by mindas
    I am trying to write a simple bash script that is listening on a port and responding with a trivial HTTP response. My specific issue is that I am not sure if the port is available and in case of bind failure I fall back to next port until bind succeeds. So far to me the easiest way to achieve this was something like: for (( i=$PORT_BASE; i < $(($PORT_BASE+$PORT_RANGE)); i++ )) do if [ $DEBUG -eq 1 ] ; then echo trying to bind on $i fi /usr/bin/faucet $i --out --daemon echo test 2>/dev/null if [ $? -eq 0 ] ; then #success? port=$i if [ $DEBUG -eq 1 ] ; then echo "bound on port $port" fi break fi done Here I am using faucet from netpipes Ubuntu package. The problem with this is that if I simply print "test" to the output, curl complains about non-standard HTTP response (error code 18). That's fair enough as I don't print HTTP-compatible response. If I replace echo test with echo -ne "HTTP/1.0 200 OK\r\n\r\ntest", curl still complains: user@server:$ faucet 10020 --out --daemon echo -ne "HTTP/1.0 200 OK\r\n\r\ntest" ... user@client:$ curl ip.of.the.server:10020 curl: (56) Failure when receiving data from the peer I think the problem lies in how faucet is printing the response and handling the connection. For example if I do the server side in netcat, curl works fine: user@server:$ echo -ne "HTTP/1.0 200 OK\r\n\r\ntest\r\n" | nc -l 10020 ... user@client:$ curl ip.of.the.server:10020 test user@client:$ I would be more than happy to replace faucet with netcat in my main script, but the problem is that I want to spawn independent server process to be able to run client from the same base shell. faucet has a very handy --daemon parameter as it forks to background and I can use $? (exit status code) to check if bind succeeded. If I was to use netcat for a similar purpose, I would have to fork it using & and $? would not work. Does anybody know why faucet isn't responding correctly in this particular case and/or can suggest a solution to this problem. I am not married neither to faucet nor netcat but would like the solution to be implemented using bash or it's utilities (as opposed to write something in yet another scripting language, such as Perl or Python).

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  • Why fork() before setsid()

    - by corentin.kerisit
    Why fork() before setsid() to daemonize a process ? Basically, if I want to detach a process from its controlling terminal and make it a process group leader : I use setsid(). Doing this without forking before doesn't work. Why ? Thanks :)

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  • What to do when the programming activity becomes a problem?

    - by gablin
    I once saw a program (can't remember which) where it talked about people "experiencing flow" when they are doing something they are passionate about. When "in flow", they tend to lose track of time and surrounding, concentrating only on their activity at hand. This happens a lot for me when I program; most particularly when I face a problem. I refuse to give up until it's solved. This usually leads to hours just rushing by and I forget to eat lunch, dinner gets pushed into far into the evening, and when I finally look at the clock, it's way into the wee-hours of the night and I will only get a few hours of sleep before having to rise early in the morning. (This is not to say that I'm in flow only when facing a problem - but I find it particularly hard to stop programming and step back when there's something I can't solve immediately.) I love programming, but I hate it when it disrupts my normal routines (most importantly eating and sleeping patterns). And sitting still for so many hours, staring a screen, is not healthy. Please, any ideas on how I can get my rampant programming activity under control?

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  • Which programming language should i choose? (much more info inside) [closed]

    - by Andreas
    I am not completely sure if this is the right place to put this question, but since it's the programming thread I guessed that there's many experienced programmers here. :) Ok, hello! My name is Andreas and I am a 16 years old guy from Norway. For some time now I've wanted to learn a programming language. Six months ago I started learning C++, but quit withing a week due to lack of motivation. The same thing happend only 2 months ago when I tried to learn Lua. I wanted to program mods to the game Garry's mod, and was really motivated. Then I stopped playing the game, and the programming stopped with it. Today though I am ready again. The only difference is that I am not completely sure what I want to do with the language. I only want to create something, and I miss the progress of failing and enduring hard work until I finally solve the problem I've worked on for hours. What I am trying to say is; Is there any program out there that allows me, a complete noob (I didn't learn that much in a week, so I like to call myself a beginner), to create apps, mods or something similar but at the same time being qualified as a first time language? I was thinking of Java, because Android, Minecraft and many other applications and games use it. But I've heard that it is going to be replaced by a program called HTML 5 (whatever that is), is this true? I certainly don't want to spend many hours of my life on something that is useless in a year or two. Hopefully I didn't make this too complicated. I know that it is hard to recommend something when I don't have a goal, but I really don't know what to say. Have a good day kind folks! - Andreas EDIT:* I did not know that this was an off topic question, really sorry!

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  • Is there any place to find real-world usage-style tutorials for programming languages?

    - by OleDid
    Let's face it. When you want to learn something completely new, be it mathematics or foreign languages, it's easiest to learn when you get real world scenarios in front of you, with theory applied. For example, trigonometry can be extremely interesting when applied to creation of 2D platform games. Norwegian can be really interesting to learn if you live in Norway. When I try to look at a new programming language, I always find these steps the hardest: What tools do I need to compile and how do I do it Introduction-step: Why is this programming language so cool? Where and how is it used? (The step I am looking for, real-world scenarios) The rest, deep diving into the language, pure theory and such, is often much easier if you have completed step 1 and 2. Because now you know what it's all about, and can just read the specification when you need to. What I ask is, do you have any recommendations for places I can find such material for programming languages? Be it websites or companies selling books in this style, I'm interested. Also, I am interested in all languages. (If I had found a "real-world usage" explained for even INTERCAL, I would be interested). In some other thread here, I found a book called "Seven Languages in Seven Weeks". This is kind of what I am looking for, but I believe there must be "more like this".

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  • viable part-time career in IT/programming?

    - by Rider
    Hi, I'd like to ask for some career advice from you people. Is there a viable job/career that can be done in programming/IT for the long term? Right now, I am thinking about website (PHP?) developer path. My background: I have a degree in computer science and have been a programmer/system analyst for almost 10 years. Lately I took a big break from programming and studied for a B.arch. degree (yes architecture), only to discover that architecture offers zero (0) jobs where I'm from, for 3 years already (and no, I am not going to move and the grass in not greener in other places). I have never been particularly interested in programming, in fact I was bored by it. But I was always quite good at both programming and system analysis, and very valued by practically all my employers. On the other hand, I have never been valued or offered a good job in any other field (although I can do many things, like design, architecture, translations, documentation, teaching, etc etc.) I guess the human component has been always more important for me in programming jobs - I value all the good people I worked with, but not projects. However, I have about zero skills or desire to be a project manager. I also have close to zero skills for selling myself. I like it best when I can do "my thing", have my niche, have an ownership of some project. Right now my career perspective is to do part time programming and to part time teach yoga. I have already started the yoga teaching part. Do you think that part time programming is viable? And what niche works best for that? I have considered web development, QA, or software development in a company like I did before. However, my fear is that when you do programming part-time, you get the most boring coding work, only to see your colleagues move to more interesting projects and up their respective career ladders. I also fear that part-timers are not especially needed either. And, since I don't share much enthusiasm at programming, I'd rather not be around young programmers boiling with geeky enthusiasm about coding, but rather QA mindset with people from different backgrounds and life paths might work better for me. Thanks for any advice, --Rider

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  • samba sync password with unix password on debian wheezy

    - by Oz123
    I installed samba on my server and I am trying to write a script to spare me the two steps to add user, e.g.: adduser username smbpasswd -a username My smb.conf states: # This boolean parameter controls whether Samba attempts to sync the Unix # password with the SMB password when the encrypted SMB password in the # passdb is changed. unix password sync = yes Further reading brought me to pdbedit man page which states: -a This option is used to add a user into the database. This com- mand needs a user name specified with the -u switch. When adding a new user, pdbedit will also ask for the password to be used. Example: pdbedit -a -u sorce new password: retype new password Note pdbedit does not call the unix password syncronisation script if unix password sync has been set. It only updates the data in the Samba user database. If you wish to add a user and synchronise the password that im- mediately, use smbpasswd’s -a option. So... now I decided to try adding a user with smbpasswd: 1st try, unix user still does not exist: root@raspberrypi:/home/pi# smbpasswd -a newuser New SMB password: Retype new SMB password: Failed to add entry for user newuser. 2nd try, unix user exists: root@raspberrypi:/home/pi# useradd mag root@raspberrypi:/home/pi# smbpasswd -a mag New SMB password: Retype new SMB password: Added user mag. # switch to user pi, and try to switch to mag root@raspberrypi:/home/pi# su pi pi@raspberrypi ~ $ su mag Password: su: Authentication failure So, now I am asking myself: how do I make samba passwords sync with unix passwords? where are samba passwords stored? Can someone help enlighten me?

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  • How to improve problem solving skills/programming skills

    - by kaibuki
    Hi All, I am new to programming, and have been given many interviews for jobs, but what I lag is the concepts and skills of general problem solving not respect to any particular programming language. are there any books or material available which can help me upgrade my programming skills. looking forward for you guys to share your views. Thanks a millions.. Kai

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  • How do the young start programming nowadays

    - by PP
    Back in the late 80s/early 90s I learned GWBasic on MS-DOS. Then Turbo Pascal. Then Turbo C/Asm. Later I stumbled into PHP and finally made a career out of Perl programming. I'm curious how actual under-25s found their way into programming. There is a lot of discussion about what path you would steer your children if you wanted them to learn programming, but I would like to hear from the newer generation to find out their more modern experiences about becoming a programmer. Note: no stories from people who first discovered programming at university.

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  • Perl: Event-driven Programming

    - by Shiftbit
    Is there any POSIX signals that I could utilize in my perl program to create event-driven programming? Currently I have multi-process program that is able to cross communicate but my parent thread is only able to listen to listen at one child at a time. foreach (@threads) { sysread(${$_}{'read'}, my $line, 100); chomp($line); print "Parent hears: $line\n"; } The problem is that the parent sits in a continual wait state until it receives it a signal from the first child before it can continue on. I am relying on 'pipe' for my intercommunication. My current solution is very similar to: http://stackoverflow.com/questions/2558098/how-can-i-use-pipe-to-facilitate-interprocess-communication-in-perl If possible I would like to rely on a $SIG{...} event or any non-CPAN solution.

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  • Windows Network Programming

    - by bdhar
    I am planning to get some good book for Windows Socket Programming in VC++. I have 2+ years of experience in working with VC++/ATL/COM/MFC; but not in the networking domain. I have been doing some search in Google for "Windows network programming" books. There are few but they have both good and bad comments scattered all over; and I am not able to decide anything. Please recommend some good book with Pros and Cons. The books I found are below. Windows Sockets Network programming Network Programming for Microsoft Windows Thanks.

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  • Signs to Quit Programming?

    - by acidzombie24
    I was hanging out with two people and one of them had a design book and the other was talking to me about programming and design. He said he had difficulties programming and wondered what are signs that you should not or should stop programming? He wanted to know if he should stick to design and i said i didnt know since i havent seen him do either. How does one know if he or she should quit programming and stick to another discipline? and what are some signs?

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  • Is literate programming dead?

    - by Stephen
    A fair bit is written about literate programming, but I've yet to see any project that uses it in any capacity, nor have I seen it used to teach programming. My sample may small, so I'm looking for evidence that literate programming exists and is successful in the real world.

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  • Functional Programming - Lots of emphasis on recursion, why?

    - by peakit
    I am getting introduced to Functional Programming [FP] (using Scala). One thing that is coming out from my initial learnings is that FPs rely heavily on recursion. And also it seems like, in pure FPs the only way to do iterative stuff is by writing recursive functions. And because of the heavy usage of recursion seems the next thing that FPs had to worry about were StackoverflowExceptions typically due to long winding recursive calls. This was tackled by introducing some optimizations (tail recursion related optimizations in maintenance of stackframes and @tailrec annotation from Scala v2.8 onwards) Can someone please enlighten me why recursion is so important to functional programming paradigm? Is there something in the specifications of functional programming languages which gets "violated" if we do stuff iteratively? If yes, then I am keen to know that as well. PS: Note that I am newbie to functional programming so feel free to point me to existing resources if they explain/answer my question. Also I do understand that Scala in particular provides support for doing iterative stuff as well.

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  • Cancel UDP recvfrom in C on Unix

    - by hora
    I'm just starting to learn how network programming in C works, and I've written a small program that sends messages to and from a UNIX terminal. I'm using pthreads in my program, one of which essentially just waits on recvfrom() to receive a message. However, I want to be able to close all threads properly if the users chooses to quit the program. The way I have it set up right now, a different thread just cancels the thread waiting on recvfrom, but I'm worried this might not be a good idea since I'm leaving sockets unclosed and I'm not freeing all the memory I allocated. Is there a way to cancel a recvfrom() call, or some way to run a certain routine upon cancelling a pthread? Thanks.

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  • Is functional GUI programming possible?

    - by eman
    I've recently caught the FP bug (trying to learn Haskell), and I've been really impressed with what I've seen so far (first-class functions, lazy evaluation, and all the other goodies). I'm no expert yet, but I've already begun to find it easier to reason "functionally" than imperatively for basic algorithms (and I'm having trouble going back where I have to). The one area where current FP seems to fall flat, however, is GUI programming. The Haskell approach seems to be to just wrap imperative GUI toolkits (such as GTK+ or wxWidgets) and to use "do" blocks to simulate an imperative style. I haven't used F#, but my understanding is that it does something similar using OOP with .NET classes. Obviously, there's a good reason for this--current GUI programming is all about IO and side effects, so purely functional programming isn't possible with most current frameworks. My question is, is it possible to have a functional approach to GUI programming? I'm having trouble imagining what this would look like in practice. Does anyone know of any frameworks, experimental or otherwise, that try this sort of thing (or even any frameworks that are designed from the ground up for a functional language)? Or is the solution to just use a hybrid approach, with OOP for the GUI parts and FP for the logic? (I'm just asking out of curiosity--I'd love to think that FP is "the future," but GUI programming seems like a pretty large hole to fill.)

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  • How to study programming with C language

    - by gurugio
    I am using only C for 5 years. So I am sure that I know C grammer, but I have no idea how to advance programming skills. There are many books for modern languages (such as C++, Java) to study programming skills like the refactoring or pattern, software architecture. But no book is written with C language. The book author say that his/her book is not language-dependent, but I don't think so. How can I advance my programming skills? I have to study modern language and read the books? Are there books about software design or programming skill written with C?

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  • Where to read about programming?

    - by minx
    I'm a programmer for some time now yet I haven't found the right websites which offer me the information I'm interested in. I've looked at TechCrunch, Slashdot, etc. but there wasn't so much actually about programming. When something urgently important happens in the programming world, where could I read it first? What are some good sites/communities around programming?

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