System Calls

The following are the 13 important library or system calls that
are covered in the below example code.




  1.   
memset() : This
function fills the first n bytes of the memory area pointed to by s with the
constant byte c.




  2.   
fopen() : This
function opens the file whose name is the string pointed to by its first
argument and associates a stream with it.




  3.   
getcwd() : This
function return a null-terminated string containing an absolute pathname that
is the current working directory of the calling process




  4.   
getuid() : This
function returns the real user ID of the calling process




  5.   
snprintf() : This
function produces output according to a format and writes the output to a
buffer.




  6.   
fwrite() : This
function is used to write data to a stream




  7.   
fflush() : This
function forces a write of all user space buffered data on to a particular
stream




  8.   
fclose() : This
function flushes the associated stream and closes the underlying file
descriptor.




  9.   
system() : This
function executes a command




  10.   sleep () : This function makes the calling process
sleep until specified seconds have elapsed or a signal arrives which is not
ignored.




  11.   opendir() : This function opens a directory stream




  12.   readdir() : This function reads the directory which is opened as
a stream




  13. atoi() : This function converts ascii argument to
integer.