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Old 09-29-2014, 10:21 AM   #1
tn12
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Registered: Sep 2014
Posts: 2

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Linux System Calls


I want to learn about programming a linux system call using C language. I want to know a good source which teaches both code and theory in detail and explanatory manner
 
Old 09-29-2014, 10:27 AM   #2
jdkaye
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This link should get you started. After that you can have a look at this document.
jdk
 
Old 09-29-2014, 11:48 AM   #3
tn12
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Registered: Sep 2014
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Here he/she just includes libraries/API and calls function access() rather than showing the function(System cAll) defintion. Refer to code if you need










#include <errno.h>
#include <stdio.h>
#include <unistd.h>
int main (int argc, char* argv[])
{
char* path = argv[1];
int rval;
/* Check file existence. */
rval = access (path, F_OK);
if (rval == 0)
printf (%s exists\n, path);
else {
if (errno == ENOENT)
printf (%s does not exist\n, path);
else if (errno == EACCES)
printf (%s is not accessible\n, path);
return 0;
}
/* Check read access. */
rval = access (path, R_OK);
if (rval == 0)
printf (%s is readable\n, path);
else
printf (%s is not readable (access denied)\n, path);
/* Check write access. */
rval = access (path, W_OK);
if (rval == 0)
printf (%s is writable\n, path);
else if (errno == EACCES)
printf (%s is not writable (access denied)\n, path);
else if (errno == EROFS)
printf (%s is not writable (read-only filesystem)\n, path);
return 0;
}
 
  


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