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  • Using Unix Process Controll Methods in Ruby

    - by John F. Miller
    Ryan Tomayko touched off quite a fire storm with this post about using Unix process control commands. We should be doing more of this. A lot more of this. I'm talking about fork(2), execve(2), pipe(2), socketpair(2), select(2), kill(2), sigaction(2), and so on and so forth. These are our friends. They want so badly just to help us. I have a bit of code (a delayed_job clone for DataMapper that I think would fit right in with this, but I'm not clear on how to take advantage of the listed commands. Any Ideas on how to improve this code? def start say "*** Starting job worker #{@name}" t = Thread.new do loop do delay = Update.work_off(self) break if $exit sleep delay break if $exit end clear_locks end trap('TERM') { terminate_with t } trap('INT') { terminate_with t } trap('USR1') do say "Wakeup Signal Caught" t.run end end

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  • Parallelism in Python

    - by fmark
    What are the options for achieving parallelism in Python? I want to perform a bunch of CPU bound calculations over some very large rasters, and would like to parallelise them. Coming from a C background, I am familiar with three approaches to parallelism: Message passing processes, possibly distributed across a cluster, e.g. MPI. Explicit shared memory parallelism, either using pthreads or fork(), pipe(), et. al Implicit shared memory parallelism, using OpenMP. Deciding on an approach to use is an exercise in trade-offs. In Python, what approaches are available and what are their characteristics? Is there a clusterable MPI clone? What are the preferred ways of achieving shared memory parallelism? I have heard reference to problems with the GIL, as well as references to tasklets. In short, what do I need to know about the different parallelization strategies in Python before choosing between them?

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  • Ruby Rack: startup and teardown operations (Tokyo Cabinet connection)

    - by clint.tseng
    I have built a pretty simple REST service in Sinatra, on Rack. It's backed by 3 Tokyo Cabinet/Table datastores, which have connections that need to be opened and closed. I have two model classes written in straight Ruby that currently simply connect, get or put what they need, and then disconnect. Obviously, this isn't going to work long-term. I also have some Rack middleware like Warden that rely on these model classes. What's the best way to manage opening and closing the connections? Rack doesn't provide startup/shutdown hooks as I'm aware. I thought about inserting a piece of middleware that provides reference to the TC/TT object in env, but then I'd have to pipe that through Sinatra to the models, which doesn't seem efficient either; and that would only get be a per-request connection to TC. I'd imagine that per-server-instance-lifecycle would be a more appropriate lifespan. Thanks!

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  • How do I Send Email from the Command Line?

    - by Joseph Pecoraro
    I would like to quickly send email from the command line. I realize there are probably a number of different ways to do this. I'm looking for a simple way to do this from a linux terminal (likely a bash shell but anything should do) and an alternative way to do this on Windows. I want to be able to whip up an email right on the command line or have the flexibility to pipe the message into the command line program. How would you go about doing this? If you have small scripts that would be fine as well. Thanks in advance.

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  • MySQL Export with Column Heading

    - by st4nt0n
    Hello - I am very, very, new to mySQL. I've got experience in general technical terms, but not with the syntax or concepts of mySQL. I have been tasked with exporting a table from MySQL into a pipe delimited .txt or .xls that I can use to add 7500 more records to manually, then import back into the table. I tried to use INTO OUTFILE, but I don't get column headings, which I need for reference to merge the new records. Is there a good resource that can explain this to a complete novice? I would usually go down to my bookstore and start learning, but I'm on a bit of a time crunch. Thanks all!

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  • sending control+c (SIGINT) to NSPIPE in objective-c

    - by Ron
    Hello, I am trying to terminate an openvpn task, spawned via NSTask. My question: Should I send ctrl+c (SIGINT) to the input NSPipe for my NSTask? inputPipe = [NSPipe pipe]; taskInput = [inputPipe fileHandleForWriting]; NSString dataString = @"\cC"; [taskInput writeData:[dataString dataUsingEncoding: [NSString defaultCStringEncoding]]]; Alternatively, I was thinking about using kill( pid, SIGINT ); but it would be much more complicated since the process ID has to be determined via a detour ([task processIdentifier] does not help here) - the original NSTask calls: /bin/bash -c sudo -S | mypassword .... That's not nice, I know but it is only called once and the sudo password has been entered in that case already. thanks for any suggestions/opinions/etc. Ron

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  • Python subprocess.Popen

    - by Albert
    I have that code: #!/usr/bin/python -u localport = 9876 import sys, re, os from subprocess import * tun = Popen(["./newtunnel", "22", str(localport)], stdout=PIPE, stderr=STDOUT) print "** Started tunnel, waiting to be ready ..." for l in tun.stdout: sys.stdout.write(l) if re.search("Waiting for connection", l): print "** Ready for SSH !" break The "./newtunnel" will not exit, it will constantly output more and more data to stdout. However, that code will not give any output and just keeps waiting in the tun.stdout. When I kill the newtunnel process externally, it flushes all the data to tun.stdout. So it seems that I can't get any data from the tun.stdout while it is still running. Why is that? How can I get the information? Note that the default bufsize for Popen is 0 (unbuffered). I can also specify bufsize=0 but that doesn't change anything.

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  • read subprocess stdout line by line

    - by Caspin
    My python script uses subprocess to call a linux utility that is very noisy. I want to store all of the output to a log file, but only show some of it to the user. I thought the following would work, but the output does show up in my application until the utility has produced a significant amount of output. #fake_utility.py, just generates lots of output over time import time i = 0 while True: print hex(i)*512 i += 1 time.sleep(0.5) #filters output import subprocess proc = subprocess.Popen(['python','fake_utility.py'],stdout.subprocess.PIPE) for line in proc.stdout: #the real code does filtering here print "test:", line.rstrip() The behavior I really want is for the filter script to print each line as it is received from the subprocess. Sorta like what tee does but with python code. What am I missing? Is this even possible?

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  • How to allow netNamedPipeBinding to work with requiring UAC?

    - by Rohit
    I have a service running under Local system account. I have an application that run in a non-UAC mode. Both interact with each other as both act as server and client. Application as client can communicate with Service. But Service as client cannot communicate with application. If I run with UAC the problem is solved. <customBinding> <binding name="net.pipe"> <namedPipeTransport /> </binding> </customBinding>

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  • Python: Converting a tuple to a string with 'err'

    - by skylarking
    Given this : import os import subprocess def check_server(): cl = subprocess.Popen(["nmap","10.7.1.71"], stdout=subprocess.PIPE) result = cl.communicate() print result check_server() check_server() returns this tuple: ('\nStarting Nmap 4.53 ( http://insecure.org ) at 2010-04-07 07:26 EDT\nInteresting ports on 10.7.1.71:\nNot shown: 1711 closed ports\nPORT STATE SERVICE\n21/tcp open ftp\n22/tcp open ssh\n80/tcp open http\n\nNmap done: 1 IP address (1 host up) scanned in 0.293 seconds\n', None) Changing the second line in the method to result, err = cl.communicate() results in check_server() returning : Starting Nmap 4.53 ( http://insecure.org ) at 2010-04-07 07:27 EDT Interesting ports on 10.7.1.71: Not shown: 1711 closed ports PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh 80/tcp open http Nmap done: 1 IP address (1 host up) scanned in 0.319 seconds Looks to be the case that the tuple is converted to a string, and the \n's are being stripped.... but how? What is 'err' and what exactly is it doing?

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  • Auto SSH and execute script

    - by rohanbk
    I have roughly 12 computers that each have the same script on them. This script merely pings all the other machines, and prints out whether the machine is "reachable" or "unreachable". However, it is inefficient to login to each machine manually using ssh to execute this script. Suppose I'm logged into node 1. Is there any way to for me to login to node 2-12 automatically using SSH, execute the ping script, pipe the results to a file, logout and proceed to the next machine? Some kind of bash shell script? I'm afraid I'm at a loss here since I haven't had experience with shell-scripting before.

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  • How to determine what invokes User Access Control restrictions?

    - by MX4399
    In a Delphi app intended to build an internet software update service for my software, the Windows 7 UAC system requests authorization from the user to run the exe.The following possible contentious/risk areas exist in the code: A named pipe server is created for communications TCP is used for FTP and HTTP SHGetSpecialFolderPath api call is used Before these items where added UAC did not activate, removing each in turn including all unit reference and then ending with the bare bones exe still causes the UAC event - so its not possible say what is causing it. On top of this Delphi 2007 now requires being launced as an administrator to launcg a debugging process for the app. Question 1 : How can I see what is causing this besides starting from scratch in a new exe - IOW is there a log somewhere I can check Question 2 : Will using a signed exe using authenticode still cause the UAC alert to show

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  • Dealing with a badly formatted CSV file

    - by Josh K
    I have an exceptionally bad CSV file. Although I "solved" the problem in the end by manually writing scripts to process and reprocess this specific file I wanted to know if there were any other solutions out there. You have a CSV file that has all the fields terminated by | (pipe) characters. Running a quick check shows you that there are 53 fields in the file. The person who gave you the file claims there there are only 28 fields. Not all of the fields have information in them. For example there are five custom_field_{num} fields which may or may not have data. How would you get this into a database nicely? The ideal solution (and one I searched high and low for) would be to just throw it all into a table with no column names or specifications. Then remove any columns that were completely blank and then give them titles and specifications.

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  • Bypassing Javascript form handler

    - by Ben Aston
    We are writing an ASP.NET MVC application. By default, if the client browser has Javascript, the handler for every form on the page is set, by Javascript, to be one that sends the submission down an Ajax "pipe" (progressive enhancement). But, for one form (on a page of several), I'd like this handler to be bypassed/ignored. Is there a simple way to do this? Perhaps by overriding the handler by specifying my own onsubmit event directly in the DOM - or some other method? We use jQuery, so those libraries are available to me.

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  • Connect to an existing process

    - by user360807
    Hole thing is happening on the mac os x. Let's assume that I've opened an program by clicking on an .app icon. It's a python program with GUI which has a separate process that waits for a user input. But as I've opened it by clickin .app icon I dont have access to it's input as I would have if I opened it in Terminal. And the question is: How can I connect new Terminal window to this running program? I tried pipes but I'm not sure how to use them correctly. My guess was to find PID of the app that is running and then pipe to this program by giving a PID. But I have no idea how to do it. I hope you were able to understand what's the problem. Sorry for my weak english :)

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  • Can a repeated piece of regular expression create multiple groups? Such as this example...

    - by Yousui
    Hi guys, I'm using RUBY 's regular expression to deal with text such as ${1:aaa|bbbb} ${233:aaa | bbbb | ccc ccccc } ${34: aaa | bbbb | cccccccc |d} ${343: aaa | bbbb | cccccccc |dddddd ddddddddd} ${3443:a aa|bbbb|cccccccc|d} ${353:aa a| b b b b | c c c c c c c c | dddddd} I want to get the trimed text between each pipe line. For example, for the first line of my upper example, I want to get the result aaa and bbbb, for the second line, I want aaa, bbbb and ccc ccccc. Now I have wrote a piece of regular expression and a piece of ruby code to test it: array = "${33:aaa|bbbb|cccccccc}".scan(/\$\{\s*(\d+)\s*:(\s*[^\|]+\s*)(?:\|(\s*[^\|]+\s*))+\}/) puts array Now my problem is the (?:\|(\s*[^\|]+\s*))+ part can't create multiple groups. I don't know how to solve this problem, because the number of text I need in each line is variable. Anyone can help? Great thanks.

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  • Bash: how to supress newlines?

    - by gilgongo
    I'm trying to extract fields from a pipe-delimited file and provide them as arguments to an external program in a loop. The file contains lines like this: value1|value2 value3|value4 So I came up with: while read line; do echo -n "${line}" | awk -F '|' '{print $1}'; echo -n " something "; echo -n "${line}" | awk -F '|' '{print $2}'; echo " somethingelse"; done < <(cat $FILE) I want to see the following output: value1 something value2 somethingelse value3 something value4 somethingelse But instead I'm getting: value1 something value2 somethingelse value3 something value4 somethingelse Perhaps I shouldn't be using echo?

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  • Connection Timeout Extension/Detection

    - by ircmaxell
    Well, let me start off by explaining what I'm trying to do. I have an application that stalls a HTTP connection until new data is available (sometimes a few seconds, sometimes 30 minutes or so). Right now, the system works fine if the data is sent within a few minutes. The problem I'm facing, is that it doesn't seem that XHR recognizes a dropped connection... So instead of killing the current connection and reconnecting when it detects a dropped connection, it just sits there. I'd really not like to have it force-reconnect every minute or two (That's one reason this app was written, to stop the need for polling). So, my questions are as follows: Is there a way to detect a dropped (not closed) TCP connection with XHR? Is there a way that I can tell XHR not to timeout (I saw IE8 has the .timeout property) Would it be better to send a header (or some other content) every now and then (say once per minute) down the pipe to keep the connection open? Thanks.

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  • C IPC waiting for child

    - by Gary
    So I have a program which creates a child process and executes a command (for example, ls). The parent will then use pipes to send to and get from the child. This works fine when I'm inputting commands myself from the command line. However, when the input comes from a file, it seems like the child doesn't have enough time to run and I get NULL when reading from the pipe - even though there will be information coming from it. Short of using sleep(), is there a better way to make sure the child has run before trying to read from it? Thanks a lot!

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  • Problem with "write" function in linux

    - by Dumitru Catalin
    I am trying to write 2 server/client programs under Linux, in which they communicate through named pipes. The problem is that sometimes when I try to write from the server into a pipe that doesn't exist anymore (the client has stopped), I get a "Resource temporarily unavailable" error and the server stops completely. I understand that this is caused by using a O_NONBLOCK parameter when opening the fifo chanel, indicating the point where the program would usually wait until it could write again in the file, but is there a way to stop this behavior, and not halt the entire program if a problem occurs (shouldn't the write command return -1 ad the program continue normally)? And another strange thing is that this error only occurs when running the programs outside the ide (eclipse). If I run both programs inside eclipse, on error the write function just returns -1 and the programs continues normally.

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  • Capturing stdout within the same process in Python

    - by danben
    I've got a python script that calls a bunch of functions, each of which writes output to stdout. Sometimes when I run it, I'd like to send the output in an e-mail (along with a generated file). I'd like to know how I can capture the output in memory so I can use the email module to build the e-mail. My ideas so far were: use a memory-mapped file (but it seems like I have to reserve space on disk for this, and I don't know how long the output will be) bypass all this and pipe the output to sendmail (but this may be difficult if I also want to attach the file)

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  • Error(2,7): PLS-00428: an INTO clause is expected in this SELECT statement

    - by omgzor
    I'm trying to create this trigger and getting the following compiler errors: create or replace TRIGGER RESTAR_PLAZAS AFTER INSERT ON PLAN_VUELO BEGIN SELECT F.NRO_VUELO, M.CAPACIDAD, M.CAPACIDAD - COALESCE(( SELECT count(*) FROM PLAN_VUELO P WHERE P.NRO_VUELO = F.NRO_VUELO ), 0) as PLAZAS_DISPONIBLES FROM VUELO F INNER JOIN MODELO M ON M.ID = F.CODIGO_AVION; END RESTAR_PLAZAS; Error(2,7): PL/SQL: SQL Statement ignored Error(8,5): PL/SQL: ORA-00933: SQL command not properly ended Error(8,27): PLS-00103: Encountered the symbol "end-of-file" when expecting one of the following: begin case declare end exception exit for goto if loop mod null pragma raise return select update while with <an identifier> <a double-quoted delimited-identifier> <a bind variable> << close current delete fetch lock insert open rollback savepoint set sql execute commit forall merge pipe Error(2,1): PLS-00428: an INTO clause is expected in this SELECT statement What's wrong with this trigger?

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  • C signal parent process from child

    - by Gary
    I'm trying to solve a problem I've got where a child process runs execvp() and needs to let the parent know if it returns. So, after the execvp() returns (because there's been an error), how can I tell the parent that this particular event has happened so it can handle it. There's one method of writing a string of text through the pipe I'm using and then reading that from the parent.. but it seems a bit sloppy. Is there a better way? Thanks!

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  • Filling in a multi-choice field in a Sharepoint Doc-Lib using SetDocsMetaInfo Frontpage Server Extentions RPC method

    - by notnot
    I've been given a big chunk of code which eventually calls upon the SetDocsMetaInfo method from Frontpage Server Extension RPC. This is easy enough for most document uploading and property updating, except when dealing with multichoice fields. I've been scouring through MSDN and I can't find anything on how to fill in multiple values for such a field. The general syntax for properties is something like this: [SR|default], with the type (string in this case) followed by a pipe and then the value to be written. Does anyone know the syntax for multichoice fields? references: MSDN: SetDocsMetaInfo

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  • Perl standard input with argument inside Bash

    - by neversaint
    I want to have such pipe in bash #! /usr/bin/bash cut -f1,2 file1.txt | myperl.pl foo | sort -u Now in myperl.pl it has content like this my $argv = $ARG[0] || "foo"; while (<>) { chomp; if ($argv eq "foo") { # do something with $_ } else { # do another } } But why the Perl script can't recognize the parameter passed through bash? Namely the code break with this message: Can't open foo: No such file or directory at myperl.pl line 15. What the right way to do it so that my Perl script can receive standard input and parameter at the same time?

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