I am currently working to show call stack of the current thread from the code itself. For this purpose, I am analyzing StackWalk64 and CaptureStackBackTrace windows API. I will update the post once I get through it.

Though, external utilities can also be used. user dump of the process can be taken to see the call stack. Solaris (and linux) has pstack command which is very excellent utility.

Please leave a comment if you have more information regarding this.

Sometimes, core file is not generated for a process which has setid bit enabled. Use following command to enable the core generation for such processes -

coreadm -e proc-setid

Please see here for more options to use with coreadm.

Device drivers are usually not paged. For example, interrupt routine must be in nonpaged memory because interrupt can occur anytime. Paged pool can be allocated and accessed at IRQL < DISPATCH_LEVEL.

For more information, please visit this blog.

Fsutil file createnew

For example:

fsutil file createnew C:\file_100MB.dat 104857600
will create a 100MB file (104,857,600B = 100MB) named “file_100MB.dat” in C drive.

#pragma pack(push, 1)
//Define your structure here
#pragma pack(pop)
//Structure padding is re enabled.

More information can be found at MSDN. GCC follows the same specifications.

Watch is used to run a command to run at regular intervals. The basic syntax of the command is

watch [options] command

For example -

watch -n 10 ls -l will execute ls -l command every 10 seconds.

watch -d ls -l home will watch for content changes in the directory home.

Looks pretty interesting. See man pages for more options.

Happy watching.

char *malloc(size)
int size;

Of course, this tended to cause problems when trying to assign a char pointer to, say, a double pointer. Because of this a cast was required:

double *p;
p = (double *)malloc ( n * sizeof ( double ) );

However, with the advent of the ISO C standard a new generic pointer was created, the void pointer. A void pointer can be assigned to any pointer type (except function pointers) safely and without the need for a cast. Thanks to this, the calls to malloc were simplified:

double *p;
p = malloc ( n * sizeof ( double ) );

However, many still prefer to cast malloc because they feel it makes the intentions of the memory allocation more clear. There is nothing wrong with this except in the event that stdlib.h, the header which declares malloc, is not included. If the return of malloc is cast then the error which would be flagged is hidden, resulting in a difficult to find bug. Also, during maintenance, if the type of the pointer changes but the cast is not changed, once again there is a difficult to find bug. The method most experienced programmers choose is:

p = malloc ( n * sizeof *p );

There is no cast for malloc since there is no need for one, and instead of using sizeof ( type ) to determine the size of the block, sizeof *ptr is used. By dereferencing the pointer and taking its size, the proper value is given without having to worry about modifying the allocation request if the type of the pointer changes.

So should you cast malloc? No, that is the preferred method. However, you should use whichever you like provided you are aware of the issues.

# !!
This bang command, when entered into the bash shell will run the previous command. It does the same thing as hitting the up arrow to take you to the previous command and then hitting enter.

# !ls
This will run the last command that started with ‘ls’. If you ran ‘ls -al /etc/init.d’ a few commands ago and then you type ‘!ls’ the full command will be run again, assuming that you haven’t used that command since then.

# !ls:p
This will display the command instead of running it.

# !$
This one will run the last word of the previous command. This one is mainly useful for substitutions.

# !$:p
Instead of running the last word of the previous command this will print it out.

# !*
This bang command will run the previous command without the first word. This one is also only really useful for substitutions as we see in the examples that follow.

# !*:p
This will print the previous command without the first word.

Click here for examples.

After going through their bug list, I found a bug about my problem. To see the bug information, go to bug.

They have given a work around which did not work for me but it did work for some people.

Update (01-Jul-2011):
This seems to be a known bug. Even, I have faced the same issue with FC14 also. Now, I am using Kubuntu and installed FC14 on Virtual Box in windows. So far so good for me. I wish they could resolve this issue.

Please see below link for the details on the bug here.

I would definitely recommend you to read the blog series, if you are interested in Linux internals.