Begin the line with `0 0 * * 1,2,3,4,5 &lt;user&gt; &lt;command&gt;`. The first fields are minutes and hours. In this case the command will run at midnight. The stars mean: for every day of the month, and for every month. The 1 to 5 specify the days. monday to friday. 6=saturday 0=sunday.

Try this:

    # run every two hours at the top of the hour Monday through Friday
    0 */2 * * mon-fri &lt;command&gt;

I need some help finding information (or an example) of how to use texture compression for Android. I have a lot of PNG&#39;s right now and I need to reduce the amount of memory they take up. I was looking at PVR compression but I can&#39;t figure out how to use this within OpenGL.

Could some point me in the right direction or offer some examples as I cannot find anything.


Android OpenGL Texture Compression

I can only get [this SDK sample of PeerChannel SecureChat](http://msdn.microsoft.com/en-us/library/ms751534%28v=vs.90%29.aspx) to work in the following scenarios in a basic home network:

 * Locally among instances running on the same machine, or
 * Among Windows 7 machines

I *cannot* get this to work between my Windows Server 2008 R2 and any other machine (no exceptions are thrown, but the nodes never find each other and thus don&#39;t go &quot;online&quot;).  I CAN ping the IPv6 addresses among all machines. The executable has a firewall exception rule, but I have also tried disabling the Windows 2008 firewall completely.  The PRNP Service is running.

 1. **Is it possible to get it working?  How?**

 1. **Does it work on YOUR 2008 machine?**

My best guess:  I notice that in the Windows 7 machines, the &quot;Peer Networking Grouping&quot; and &quot;Peer Networking Identity Manager&quot; services are present.  The &quot;Peer Networking Grouping&quot; service&#39;s description there and online talks specifically about enabling multi-party conversations, but related to Home Groups.  This service is missing in the Windows Server machine.

So, I suspect the missing service as the reason that the SecureChat sample won&#39;t work on the Windows Server machine, but I don&#39;t understand why Microsoft would lock out Peer Channel from working on the Server product. Could this be the reason?

Thanks!

Getting MSDN PeerChannel &quot;SecureChat&quot; running on Windows Server 2008 R2

Hi I want to create a cron expression excluding saturday and sunday.


How to skip saturday and sunday in a cron expression?

<p>Hi I want to create a cron expression excluding saturday and sunday.</p>


So I typically run this command a lot: 

&gt; ssh -L 5901:myUser@computer.myHost.edu:5901

I use it to do VNC over SSH. 

How do I convert that command into something that will work in a ~/.ssh/config file? 

ex: 

    host yam
    	HostName yam.myHost.edu
    	User myUserName

all I want to do is type: 

    ssh yam

And have it open a SSH shell with a local listen port, and a remote port forwarded to it. 

Suggestions? 	

SSH Port forwarding in a ~/.ssh/config file?

Given the pid of a Linux process, I want to check, from a C program, if the process is still running.

Check if process exists given its pid

How can I recursively count files in a Linux directory?

I found this:

    find DIR_NAME -type f &#166; wc -l

But when I run this it returns the following error.

&gt; find: paths must precede expression: &#166;

Recursively counting files in a Linux directory

I am a beginner to CMAKE. Below is a simple cmake file which works well in mingw environment windows. The problem is clearly with `target_link_libraries()` function of CMAKE where I am linking libwsock32.a. In windows this works and I get the results. 

However, as expected, in Linux, the `/usr/bin/ld` will look for `-lwsock32` which is NOT there on the Linux OS. 

My Problem is: How do I instruct CMAKE to avoid linking wsock32 library in Linux OS???

Any help will be greatly appreciated. 

My Simple CMake file: 

     PROJECT(biourl)
     set (${PROJECT_NAME}_headers ./BioSocketAddress.h  ./BioSocketBase.h ./BioSocketBuffer.h ./BioSocketCommon.h  ./BioSocketListener.h  ./BioSocketPrivate.h  ./BioSocketStream.h ./BioUrl.h BioDatabase.h )

    set (${PROJECT_NAME}_sources BioSocketAddress.C  BioSocketBase.C  BioSocketCommon.C BioSocketStream.C  BioUrl.C BioDatabase.C )

    add_library(${PROJECT_NAME} STATIC ${${PROJECT_NAME}_headers} ${${PROJECT_NAME}_sources} )

    # linkers
    #find_library(ws NAMES wsock32 PATHS ${PROJECT_SOURCE_DIR} NO_SYSTEM_ENVIRONMENT_PATH NO_DEFAULT_PATH)

    target_link_libraries(${PROJECT_NAME} bioutils wsock32)

    install (TARGETS ${PROJECT_NAME}
           RUNTIME DESTINATION bin
           LIBRARY DESTINATION lib
           ARCHIVE DESTINATION lib/archive )


OS specific instructions in CMAKE: How to?

I want to define a bash alias named `kill3000` to automate the following task:

&lt;!-- language: lang-none --&gt;

    $ lsof -i:3000
    
    COMMAND   PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
    ruby    13402 zero    4u  IPv4 2847851      0t0  TCP *:3000 (LISTEN)
    
    $ kill -9 13402



shell script to kill the process listening on port 3000?

If I have a custom shell script or programs, that I created myself or downloaded from the web, and I want to be able to execute this from the CLI, is there the standard location to put this in Linux/Unix directory structure?

    /usr/bin ?
    /usr/local/bin ?
    /usr/lib ?
    /usr/sbin ?
    /bin ?
    /sbin ?
    /var ?

I usually put it under my ~/bin folder and put it in PATH, but it doesn&#39;t seem clean. And everytime I downloaded a new program, I have to put it in the PATH again.

Unix standard directory to put custom executables or scripts?

How do I use grep to search the current directory for any and all files containing the string &quot;hello&quot; and display only .h and .cc files?

How do I use grep to search the current directory for all files having the a string &quot;hello&quot; yet display only .h and .cc files?

I am wondering how you can get the system CPU usage and present it in percent using bash, for example.

Sample output:

    57%

In case there is more than one core, it would be nice if an average percentage could be calculated.

How to get overall CPU usage (e.g. 57%) on Linux

I know that I can use following command to extract a single file to the current working directory (assume I have a tar file named test.tar and a file named testfile1 and testfile2 are inside it):

    $tar xvf test.tar testfile1

And I can use -C option to extract files to another directory:

    $tar xvf test.tar -C anotherDirectory/

When I incorporate the above two techniques together, I suppose that I can extract a single file to another directory. 

    $ tar xvf test.tar testfile1 -C anotherDirectory/

But the result is I can only extract the testfile1 to the current working directory, rather than the anotherDirectory.

I want to know how can I extract a single file from tar to a different directory?

How to extract a single file from tar to a different directory?

I need unix cron command to run every 12 hours.

I have 500+ sub blogs in my server. 

This is the file i want to run every 12 hours

    http://*.mysite.com/somedir/index.php

Where * is my subdomain of my blogs.

I need cron command for all blogs. 
Is it possible to run all of them with single command?
OR do i have to create command for each blog?



cron command to run every 12 hours

I am trying to use whenever to execute a rake task onces a day. Im getting this error


    /bin/bash: bundle: command not found
    /home/app/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:247:in `to_specs&#39;: Could not find bundler (&gt;= 0) amongst [minitest-1.6.0, rake-0.8.7, rdoc-2.5.8] (Gem::LoadError)
        	from /home/app/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:256:in `to_spec&#39;
        	from /home/app/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems.rb:1210:in `gem&#39;
        	from /home/app/.rvm/gems/ruby-1.9.2-p180/bin/bundle:18:in `&lt;main&gt;&#39;


Here is my crontab

    # Begin Whenever generated tasks for: /home/af/www/app/releases/20120216172204/config/schedule.rb
    PATH=/home/af/.rvm/gems/ruby-1.9.2-p180@global/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
    
    0 0 * * * /bin/bash -l -c &#39;cd /home/af/www/app/releases/20120216172204 &amp;&amp; rvm 1.9.1-p180; RAILS_ENV=production /home/af/.rvm/gems/ruby-1.9.2-p180/bin/bundle exec rake daily:stats --silent &gt;&gt; /home/af/www/app/releases/20120216172204/log/cron.log 2&gt;&amp;1&#39;
    
    # End Whenever generated tasks for: /home/af/www/app/releases/20120216172204/config/schedule.rb


I&#39;m at a loss as to why it isn&#39;t working. If I run the command:

    cd /home/af/www/app/releases/20120216172204 &amp;&amp; rvm 1.9.1-p180; RAILS_ENV=production /home/af/.rvm/gems/ruby-1.9.2-p180/bin/bundle exec rake daily:stats --silent &gt;&gt; /home/af/www/app/releases/20120216172204/log/cron.log 2&gt;&amp;1

It works fine, not sure whats going on here.

Rails cron whenever, bundle: command not found

Ok so I have a cron that I need to run every 30 seconds.

Here is what I have:

    */30 * * * * /bin/bash -l -c &#39;cd /srv/last_song/releases/20120308133159 &amp;&amp; script/rails runner -e production &#39;\&#39;&#39;Song.insert_latest&#39;\&#39;&#39;&#39;

It runs, but is this running every 30 minutes or 30 seconds? 

Also, I have been reading that cron might not be the best tool to use if I run it that often. Is there another better tool that I can use or install on Ubuntu 11.04 that will be a better option? Is there a way to fix the above cron?


Running a cron every 30 seconds

For better or worse, we have migrated our whole [LAMP](https://en.wikipedia.org/wiki/LAMP_(software_bundle)) web application from dedicated machines to the cloud (Amazon EC2 machines). It&#39;s going great so far but the way we do [crons](https://en.wikipedia.org/wiki/Cron) is sub-optimal. I have a Amazon-specific question about how to best manage cron jobs in the cloud using &quot;the Amazon way&quot;.

**The problem**: We have multiple webservers, and need to run crons for batch jobs such as creating RSS feeds, triggering emails, many different things actually. BUT the cron jobs **need to only run on one machine** because they often write to the database so would duplicate the results if run on multiple machines.

So far, we designated one of the webservers as the &quot;master-webserver&quot; and it has a few &quot;special&quot; tasks that the other webservers don&#39;t have. The trade-off for cloud computing is reliability - we don&#39;t want a &quot;master-webserver&quot; because it&#39;s a single point of failure. We want them to all be identical and to be able to upscale and downscale without remembering not to take the master-webserver out of the cluster.

How can we redesign our application to convert Linux cron jobs into transitory work items that don&#39;t have a single point of failure?

My ideas so far:

* Have a machine dedicated to only running crons. This would be a little more manageable but would still be a single-point-of-failure, and would waste some money having an extra instance.
* Some jobs could conceivably be moved from Linux crons to [MySQL Events][1] however I&#39;m not a big fan of this idea as I don&#39;t want to put application logic into the database layer.
* Perhaps we can run all crons on all machines but change our cron scripts so they all start with a bit of logic that implements a locking mechanism so only one server actually takes action and the others just skip. I&#39;m not a fan of this idea as it sounds potentially buggy and I would prefer to use a Amazon best-practice rather than rolling our own.
* I&#39;m imagining a situation where jobs are scheduled somewhere, added to a queue and then the webservers could each be a worker, that can say &quot;hey, I&#39;ll take this one&quot;. [Amazon Simple Workflow Service][2] sounds exactly this kind of thing but I don&#39;t currently know much about it so any specifics would be helpful. It seems kind of heavy-weight for something as simple as a cron? Is it the right service or is there a more suitable Amazon service?

----------

*Update:* Since asking the question I have watched the [Amazon Simple Workflow Service][3] webinar on YouTube and noticed at 34:40 ([http://www.youtube.com/watch?v=lBUQiek8Jqk#t=34m40s][4]) I caught a glimpse of a slide mentioning cron jobs as a sample application. In their documentation page, &quot;[AWS Flow Framework samples for Amazon SWF][5]&quot;, Amazon say they have sample code for crons:

&gt; ...
&gt; **&gt; Cron jobs** In this sample, a long running workflow periodically
&gt; executes an activity. The ability to continue executions as new
&gt; executions so that an execution can run for very extended periods of
&gt; time is demonstrated.
&gt; ...

I downloaded the AWS SDK for Java ([http://aws.amazon.com/sdkforjava/][6]) and sure enough buried within a ridiculous layers of folders there is some java code (`aws-java-sdk-1.3.6/samples/AwsFlowFramework/src/com/amazonaws/services/simpleworkflow/flow/examples/periodicworkflow`).

The problem is, if I&#39;m honest, this doesn&#39;t really help as it&#39;s not something I can easily digest with my skillset. The same sample is missing from the PHP SDK and there doesn&#39;t seem to be a tutorial that walks though the process. So basically, I&#39;m still hunting for advice or tips.


  [1]: http://dev.mysql.com/doc/refman/5.6/en/events.html
  [2]: http://aws.amazon.com/swf/
  [3]: http://dev.mysql.com/doc/refman/5.6/en/events.html
  [4]: http://www.youtube.com/watch?v=lBUQiek8Jqk#t=34m40s
  [5]: http://aws.amazon.com/code/3015904745387737
  [6]: http://aws.amazon.com/sdkforjava/

How to convert Linux cron jobs to &quot;the Amazon way&quot;?

I am new to scheduling tasks with cron and crontab.  I am trying to schedule execution of a task as if I had logged on, opened a terminal, and executed it myself.

However, I scheduled a task to help me observe what $USER and $PATH a scheduled task is executing with, and this is what I found:

    $ crontab -l
    41 11 * * * echo &quot;USER: $USER&quot; &gt; ~/Desktop/cron_env.log; echo &quot;PATH: $PATH&quot; &gt;&gt; ~/Desktop/cron_env.log
    $ cat ~/Desktop/cron_env.log
    USER:
    PATH: /usr/bin:/bin

It appears as though $USER is not set, and $PATH is something very basic and/or default.  On the contrary, this is what I see when I open a terminal (logged in) and echo this same information:

    USER: aschirma
    PATH: /usr/lib/jvm/java-6-sun/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/pkg/icetools/bin:/pkg/hwtools/bin:/pkg/netscape/bin:/pkg/gnu/bin

What do I need to do to make my crontab tasks run the way I want?

crontab PATH and USER

I know there is a duplicate [here](https://stackoverflow.com/questions/8324306/cron-job-that-will-never-execute), which probably is exactly my case, though it would deserve some better explanation, which I will try to provide here.

I work with a Java web application using a Spring application context. In this context, I defined scheduled jobs using Quartz. These jobs are triggered by a cron defined in a .properties file.

The Spring context is embedded within the war, while the .properties file is on the application server (Tomcat in this particular case).

This is just fine and allows to define different crons according to the environment (development, integration, production, ...).

Now, when running this application locally on my own computer, I do not wish these jobs to be executed. Is there a way to write a cron expression which will never trigger?

Content Type	Original Author	Original Content on Stackoverflow
Question	Rakesh Sabbani	View Question on Stackoverflow
Solution 1 - Linux	Michel	View Answer on Stackoverflow
Solution 2 - Linux	SiegeX	View Answer on Stackoverflow

How to skip saturday and sunday in a cron expression?

Linux Problem Overview

Linux Solutions

Solution 1 - Linux

Solution 2 - Linux

Getting MSDN PeerChannel "SecureChat" running on Windows Server 2008 R2

Android OpenGL Texture Compression

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