It seems they are suppressed by default. Running

    $ ulimit -c unlimited

Will enable core dumps for the current terminal, and it will be placed in `/cores` as `core.PID`. When you open a new session, it will be set to the default value again.

On macOS, your crash dumps are automatically handled by [Crash Reporter][1].

You can find backtrace files by executing [Console][2] and going to *User Diagnostic Reports* section (under &#39;Diagnostic and Usage Information&#39; group) or you can locate them in `~/Library/Logs/DiagnosticReports`.

You can also check where dumps are generated by monitoring `system.log` file, e.g.

    tail -f /var/log/system.log | grep crash

The actual *core* dump files you can find in `/cores`.

See also:

- [How to generate core dumps in Mac OS X?][3]
- [Technical Note TN2118: Kernel Core Dumps][4].


  [1]: http://en.wikipedia.org/wiki/Crash_Reporter
  [2]: http://en.wikipedia.org/wiki/Console_%28OS_X%29
  [3]: https://stackoverflow.com/questions/9412156/how-to-generate-core-dumps-in-mac-os-x
  [4]: https://developer.apple.com/library/content/technotes/tn2004/tn2118.html

Additionally, the /cores directory must exist and the user running the program must have write permissions on it.

The answer above, 

&gt; ulimit -c unlimited

works -- but be sure to run that in the same terminal from which you will run the program that dumps core.  You need to run the ulimit command first.

by default, specific directories in mac osx are hidden. you might want to enable this feature in the terminal and then the core dump should be visible within the directory /cores.
&gt; defaults write com.apple.finder AppleShowAllFiles TRUE 


I have developed a User Control in Visual Studio (WinForms C#) and have a question.

I need the user of my User Control to be able to change certain string values and I would like them to be able to add the user control to their Form and click on it to bring up the Properties Pane where my User Control&#39;s custom properties will be displayed.

How can I have my own custom properties for my user control? For example:

My user control contains a TextBox, and I would like the user to be able to change the value of that TextBox via a property named &quot;Text&quot; or &quot;Value&quot; in the properties at Design-Time.

User Control - Custom Properties

I need to output 4 different floats to two decimal places.

This is what I have:

    print &#39;%.2f&#39; % var1,&#39;kg =&#39;,&#39;%.2f&#39; % var2,&#39;lb =&#39;,&#39;%.2f&#39; % var3,&#39;gal =&#39;,&#39;%.2f&#39; % var4,&#39;l&#39;

Which is very unclean, and looks bad. Is there a way to make any float in that out put &#39;%.2f&#39;? 

Note: Using Python 2.6.

Python, print all floats to 2 decimal places in output

On Mac OS X, if I send SIGQUIT to my C program, it terminates, but there is no core dump file.

Do you have to manually enable core dumps on Mac OS X (how?), or are they written to somewhere else instead of the working directory?

Where are core dumps written on Mac?

<p>On Mac OS X, if I send SIGQUIT to my C program, it terminates, but there is no core dump file.</p>
<p>Do you have to manually enable core dumps on Mac OS X (how?), or are they written to somewhere else instead of the working directory?</p>


Running &#39;`sudo gem list --local`&#39; and &#39;`gem list --local`&#39; give me differing results. My gem path is set to my home folder and only contains the gems from &#39;`gem list --local`&#39;.

It&#39;s probably not good to have gems installed in different directories on my computer, so should I have the gem path set differently, and should I always use `sudo` when installing something?

    my ~/.profile
    export PATH=/opt/local/bin:/opt/local/sbin:$PATH
    export PATH=&quot;/usr/local/bin:/usr/local/sbin:/usr/local/mysql/bin:$PATH&quot;

~/.bash_profile is empty.


&#39;sudo gem install&#39; or &#39;gem install&#39; and gem locations

While reading various C and C++ sources, I have encountered two macros `__APPLE__` and `__OSX__`. I found plenty of use of `__OSX__` in various codes, especially those originating from `*BSD` systems. 

However, sometimes I find that testing `__OSX__` only is not sufficient and I have to complete tests with `__APPLE__` macro.

The [Porting Command Line Unix Tools to Mac OS X][1] guides specifies `__APPLE__` and additionally `__APPLE_CC__` but does **not** mention `__OSX__`.

The [Porting from GCC][2] guide says:

&gt; * Use `#ifdef __GNUC__` to wrap any GCC-specific code.
&gt; * Use `#ifdef __APPLE_CC__` to wrap any Mac OS X-specific code.

Again, no mention about `__OSX__` macro.

What macro is predefined on Mac OS X platform and XCode development environment that should be used to distinguish OSX-specific code in C/C++ programs?

Where is the `__OSX__` macro defined? Is it `*BSD` specific macro?

  [1]: http://developer.apple.com/mac/library/technotes/tn2002/tn2071.html#Section10
  [2]: http://developer.apple.com/mac/library/releasenotes/DeveloperTools/GCC40PortingReleaseNotes/Articles/PortingToGCC.html

Which macro to wrap Mac OS X specific code in C/C++

I&#39;m trying to get MySQL installed to the latest version due to some installation going wrong somewhere along the line.  I run the command `gem install mysql` and I receive the following:

&gt; Building native extensions.  This
&gt; could take a while... ERROR:  Error
&gt; installing mysql: 	ERROR: Failed to
&gt; build gem native extension.
&gt; 
&gt; /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
&gt; extconf.rb extconf.rb:4: warning:
&gt; Insecure world writable dir /usr/bin
&gt; in PATH, mode 040777 extconf.rb:4:
&gt; warning: Insecure world writable dir
&gt; /usr/bin in PATH, mode 040777
&gt; extconf.rb:7: warning: Insecure world
&gt; writable dir /usr/bin in PATH, mode
&gt; 040777 mkmf.rb can&#39;t find header files
&gt; for ruby at
&gt; /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h
&gt; 
&gt; 
&gt; Gem files will remain installed in
&gt; /Library/Ruby/Gems/1.8/gems/mysql-2.8.1
&gt; for inspection. Results logged to
&gt; /Library/Ruby/Gems/1.8/gems/mysql-2.8.1/ext/mysql_api/gem_make.out

I&#39;ve searched, and tried a whole host of things, from installing specific versions to trying to reinstall ruby without any luck.

Any ideas where I may be going wrong?

I&#39;m trying to get MySQL installed to the latest version due to some installation going wrong somewhere along the line.  I run the command `gem install mysql` and I receive the following:

&gt; Building native extensions.  This
&gt; could take a while... ERROR:  Error
&gt; installing mysql: 	ERROR: Failed to
&gt; build gem native extension.
&gt; 
&gt; /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
&gt; extconf.rb extconf.rb:4: warning:
&gt; Insecure world writable dir /usr/bin
&gt; in PATH, mode 040777 extconf.rb:4:
&gt; warning: Insecure world writable dir
&gt; /usr/bin in PATH, mode 040777
&gt; extconf.rb:7: warning: Insecure world
&gt; writable dir /usr/bin in PATH, mode
&gt; 040777 mkmf.rb can&#39;t find header files
&gt; for ruby at
&gt; /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h
&gt; 
&gt; 
&gt; Gem files will remain installed in
&gt; /Library/Ruby/Gems/1.8/gems/mysql-2.8.1
&gt; for inspection. Results logged to
&gt; /Library/Ruby/Gems/1.8/gems/mysql-2.8.1/ext/mysql_api/gem_make.out

I&#39;ve searched, and tried a whole host of things, from installing specific versions to trying to reinstall ruby without any luck.

Any ideas where I may be going wrong?

**EDIT**: I installed XCode off my Snow Leopard DVD and the error just changed slightly to the following:

&gt; Building native extensions.  This could take a while...
&gt; ERROR:  Error installing mysql:
&gt; 	ERROR: Failed to build gem native extension.

&gt; /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
extconf.rb:4: warning: Insecure world writable dir /usr/bin in PATH, mode 040777
extconf.rb:4: warning: Insecure world writable dir /usr/bin in PATH, mode 040777
extconf.rb:7: warning: Insecure world writable dir /usr/bin in PATH, mode 040777
extconf.rb:17: warning: Insecure world writable dir /usr/bin in PATH, mode 040777
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lmygcc... no
checking for mysql_query() in -lmysqlclient... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

&gt; Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
	--with-mysql-config
	--without-mysql-config
	--with-mysql-dir
	--without-mysql-dir
	--with-mysql-include
	--without-mysql-include=${mysql-dir}/include
	--with-mysql-lib
	--without-mysql-lib=${mysql-dir}/lib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-mlib
	--without-mlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-zlib
	--without-zlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-socketlib
	--without-socketlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-nsllib
	--without-nsllib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-mygcclib
	--without-mygcclib
	--with-mysqlclientlib
	--without-mysqlclientlib


&gt; Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/mysql-2.8.1 for inspection.
Results logged to /Library/Ruby/Gems/1.8/gems/mysql-2.8.1/ext/mysql_api/gem_make.out


doing &quot;which mysql&quot; on the command line returns nothing, which means it&#39;s not recognizing it.  I also installed the MySQL system preferences option, and I can&#39;t stop MySQL from running.  Now I&#39;m completely stuck as what to do!

**EDIT EDIT**

I&#39;ve just completely reinstalled MySQL using this guide http://hivelogic.com/articles/installing-mysql-on-mac-os-x

Unfortunately this didn&#39;t work either, I still receive the same errors.  I can&#39;t even do mysql -uroot at the command line, I get the error of: 

ERROR 2002 (HY000): Can&#39;t connect to local MySQL server through socket &#39;/tmp/mysql.sock&#39; (2)

So I think I&#39;ve tried everything.

**SOLVED*

Sorry guys, the reason for this not working was because of the MySQL paths.  I&#39;ve blogged on it here: http://www.kieransenior.co.uk/2010/02/mysql-cant-connect-using-ruby-on-rails-mac-os-x-snow-leopard/

MySQL Install: ERROR: Failed to build gem native extension

I am getting more than a little sick of this iPhone SDK and its documentation...

I am calling AudioConverterNew

in the documentation under Returns: it says &quot;returns a status code&quot;
...
really...

so far, through playing around with the parameters I have only been able to get two different errors neither of which are listed at the bottom of the Audio Converter reference.

they are &#39;mrep&#39; and &#39;?tmf&#39; (casting the OSStatus to a char array) but the specific codes aren&#39;t really the point.

as far as I can tell, random error codes are defined in random files, so you can&#39;t just search one file, I can&#39;t find a help document that just lets you search for an error code to get more info, and from what I can tell, in OS X you can use GetMacOSStatusErrorString() to convert an error to something useful, but there is no iPhone equivalent?

any help would be greatly appreciated.

EDIT:

ok, so casting them gives them in reverse (something I checked for &#39;mrep&#39; but was not there either way round) , fmt? is in the list for the Audio Converter api, and is pretty self explanatory if a bit vague, but fair enough, still &#39;perm&#39; isn&#39;t there (although it might be something to do with the simulator not supporting aac decoding) and my general question still stands.


How do you convert an iPhone OSStatus code to something useful?

I know the `clear` command that &#39;clears&#39; the current screen, but it does this just by printing lots of newlines - the cleared contents just get scrolled up.

Is there a way to completely wipe all previous output from the terminal so that I can&#39;t reach it even by scrolling up?


How can I clear previous output in Terminal in Mac OS X?

my scripts rely heavily on external programs and scripts.
I need to be sure that a program I need to call exists. 
Manually, I&#39;d check this using &#39;which&#39; in the commandline.

Is there an equivalent to `File.exists?` for things in `$PATH`?

(yes I guess I could parse `%x[which scriptINeedToRun]` but that&#39;s not super elegant.

Thanks!
yannick

---

UPDATE: Here&#39;s the solution I retained:

   

     def command?(command)
           system(&quot;which #{ command} &gt; /dev/null 2&gt;&amp;1&quot;)
     end


--- 

### UPDATE 2: A few new answers have come in - at least some of these offer better solutions. 

### Update 3: The [ptools gem][1] has adds a &quot;which&quot; method to the File class. 


  [1]: https://github.com/djberg96/ptools

&quot;which in ruby&quot;: Checking if program exists in $PATH from ruby

I want to delete one or more specific line numbers from a file. How would I do this using sed?

Delete specific line number(s) from a text file using sed?

This can be a very simple question, I&#39;m am attempting to debug an application which generates the following segfault error in the `kern.log`

`kernel: myapp[15514]: segfault at 794ef0 ip 080513b sp 794ef0 error 6 in myapp[8048000+24000]`

Here are my questions: 

 1. Is there any documentation as to what are the diff error numbers on segfault, in this instance it is error 6, but i&#39;ve seen error 4, 5

 2. What is the meaning of the information `at bf794ef0 ip 0805130b sp bf794ef0 and myapp[8048000+24000]`?

So far i was able to compile with symbols, and when i do a `x 0x8048000+24000` it returns a symbol, is that the correct way of doing it? My assumptions thus far are the following:

- sp = stack pointer?
- ip = instruction pointer
- at = ????
- myapp[8048000+24000] = address of symbol?

How do you read a segfault kernel log message

I&#39;m looking for the Unix equivalent of Win32&#39;s [CopyFile](http://msdn.microsoft.com/en-us/library/aa363851.aspx), I don&#39;t want to reinvent the wheel by writing my own version.

How can I copy a file on Unix using C?

I am trying to write a simple bash script that will copy the entire contents of a folder including hidden files and folders into another folder, but I want to exclude certain specific folders.  How could I achieve this?

Copy folder recursively, excluding some folders

Is there a way to map a signal number (e.g. signal.SIGINT) to its respective name (i.e. &quot;SIGINT&quot;)?

I&#39;d like to be able to print the name of a signal in the log when I receive it, however I cannot find a map from signal numbers to names in Python, i.e.:
    
    import signal
    def signal_handler(signum, frame):
        logging.debug(&quot;Received signal (%s)&quot; % sig_names[signum])

    signal.signal(signal.SIGINT, signal_handler)

For some dictionary sig_names, so when the process receives SIGINT it prints:

    Received signal (SIGINT)

Get signal names from numbers in Python

I&#39;ve been trying to understand the intricacies of how POSIX threads and POSIX signals interact. In particular, I&#39;m interested in:

* What&#39;s the best way to control which thread a signal is delivered to (assuming it isn&#39;t fatal in the first place)?
* What is the best way to tell another thread (that might actually be busy) that the signal has arrived? (I already know that it&#39;s a bad idea to be using pthread condition variables from a signal handler.)
* How can I safely handle passing the information that a signal has occurred to other threads? Does this need to happen in the signal handler? (I do not in general want to kill the other threads; I need a far subtler approach.)

For reference about why I want this, I&#39;m researching how to convert the [TclX](http://sourceforge.net/projects/tclx/) package to support threads, or to split it up and at least make some useful parts support threads. Signals are one of those parts that is of particular interest.

POSIX threads and signals

I&#39;m having issues with a custom signal in a class I made.

Relevant code:

    self.parse_triggered = QtCore.pyqtSignal()

    def parseFile(self):
		self.emit(self.parse_triggered)

Both of those belong to the class: RefreshWidget.
In its parent class I have:

    self.refreshWidget.parse_triggered.connect(self.tabWidget.giveTabsData())

When I try to run the program, I get the error:

    AttributeError: &#39;PyQt4.QtCore.pyqtSignal&#39; object has no attribute &#39;connect&#39;

Help?
Thanks in advance.

PyQt4.QtCore.pyqtSignal object has no attribute &#39;connect&#39;

In my application, I want to create entries in certain tables when a new user signs up. For instance, I want to create a userprofile which will then reference their company and some other records for them. I implemented this with a post_save signal:

    def callback_create_profile(sender, **kwargs):
        # check if we are creating a new User
        if kwargs.get(&#39;created&#39;, True):
            user = kwargs.get(&#39;instance&#39;)
            company = Company.objects.create(name=&quot;My Company&quot;)
            employee = Employee.objects.create(company=company, name_first=user.first_name, name_last=user.last_name)
            profile = UserProfile.objects.create(user=user, employee=employee, partner=partner)
    # Register the callback
    post_save.connect(callback_create_profile, sender=User, dispatch_uid=&quot;core.models&quot;)

This works well when run. I can use the admin to create a new user and the other three tables get entries with sensible as well. (Except that is, the employee since the user.first_name and user.last_name aren&#39;t filled out in the admin&#39;s form when it saves. I still don&#39;t understand why it is done like that)

The problem came when I ran my test suite. Before this, I had created a bunch of fixtures to create these entries in the tables. Now I get an error that states:

    IntegrityError: duplicate key value violates unique constraint &quot;core_userprofile_user_id_key&quot;

I think this is because I have already created a company,employee and profile records in the fixture with id &quot;1&quot; and now the post_save signal is trying to recreate it.

My questios are: can I disable this post_save signal when running fixtures? Can I detect that I am running as part of the test suite and not create these records? Should I delete these records from the fixtures now (although the signal only sets defaults not the values I want to be testing against)? Why doesn&#39;t the fixture loading code just overwrite the created records?

How do people do this?

How do I prevent fixtures from conflicting with django post_save signal code?

How does one catch &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;C&lt;/kbd&gt; in C?

Catch Ctrl-C in C

What are all the things I will need to check while analyzing a core dump file?

Please tell me from scratch.



Core dump file analysis

Every time, my application crash a core dump file is not generated. I remember that few days ago, on another server it **was** generated. I&#39;m running the app using screen in bash like this:

    #!/bin/bash
    ulimit -c unlimited
    while true; do ./server; done

As you can see I&#39;m using `ulimit -c unlimited` which is important if I want to generate a core dump, but it still doesn&#39;t generate it, when I got an segmentation fault.
How can I make it work?

Core dump file is not generated

My program operates like this:

    exe -p param1 -i param2 -o param3

It crashed and generated a core dump file, `core.pid`.

I want to analyze the core dump file by

    gdb ./exe -p param1 -i param2 -o param3 core.pid

But GDB recognizes the parameters of the EXE file as GDB&#39;s input.

How do I analyze a core dump file in this situation?


How do I analyze a program&#39;s core dump file with GDB when it has command-line parameters?

I write this code to read 3 files, TM is the size of square matrix, LER the No. of rows of an array and from last value define a non-square matrix of (ler/2)*2

Then... the code read a file with some relations, all are numbers and are assign to C[ler].

Then ... C[ler] is assigned to B[ler/2][2].

Those coordinates, per row, in B[ler/2][2] are assign to a and b.

a and b are the row and the column of the matrix A[tm][tm] where to add 1.

My code crashes and I don&#39;t see what the error is.

When I try to compile it, the compiler **gcc -g -o MatSim MatSim.cpp** prompted:

    /usr/include/c++/4.6/iostream:75: undefined reference to `std::ios_base::Init::Init()&#39;
    /usr/include/c++/4.6/iostream:75: undefined reference to `std::ios_base::Init::~Init()&#39;
    collect2: ld returned 1 exit status

Also, when I try to compile it, the compiler **f77 -o MatSim MatSim.cpp** prompted:

    /tmp/cc6ewlkf.o: In function `__static_initialization_and_destruction_0(int, int)&#39;:
    MatSim.cpp:(.text+0x17ad4a): undefined reference to `std::ios_base::Init::Init()&#39;
    MatSim.cpp:(.text+0x17ad4f): undefined reference to `std::ios_base::Init::~Init()&#39;
    collect2: ld returned 1 exit status



**Solution**

The main problem was a library problem, Compile your code using:

     g++ -g -o MatSim MatSim.cpp -lstdc

Still not working?  Install libraries:

    sudo apt-get install g++-multilib





Content Type	Original Author	Original Content on Stackoverflow
Question	xyz	View Question on Stackoverflow
Solution 1 - Macos	xyz	View Answer on Stackoverflow
Solution 2 - Macos	kenorb	View Answer on Stackoverflow
Solution 3 - Macos	user666406	View Answer on Stackoverflow
Solution 4 - Macos	Joshua Richardson	View Answer on Stackoverflow
Solution 5 - Macos	Gnark	View Answer on Stackoverflow

Where are core dumps written on Mac?

Macos Problem Overview

Macos Solutions

Solution 1 - Macos

Solution 2 - Macos

Solution 3 - Macos

Solution 4 - Macos

Solution 5 - Macos

Python, print all floats to 2 decimal places in output

User Control - Custom Properties

Attributions