Write a C Program to Implement the Concept of I/O Call


Write a C Program to Implement the Concept of I/o Call.


  • creat(name, permissions) – Used to create a file with the name and mode specified. Here,     permission would be a number. 0666 means read write permissions.
  • open(name, mode) – Used to open a file name in the mode (read or write) specified. 0 is for       opening in read mode, 1 for writing and 2 for both.
  • close(fd) – Close a opened file.
  • unlink(fd) – Delete a file.
  • read(fd, buffer, n_to_read) – Read data from a file.
  • write(fd, buffer, n_to_write) – write data from to a file.
  • lseek(fd, offest, whence) – Move the read/write pointer to the specified location.


  • STEP 2- Declare the value fd
  • STEP 3- If file does not have in directory then file foo.txt is created.
  • STEP 4- print which type of error have in a code
  • STEP 5- print program detail “Success or failure
  • STEP 6- STOP


extern int errno;
int main()
int fd = open("foo.txt", O_RDONLY | O_CREAT);
printf("fd = %d/n", fd);	
if (fd ==-1)
printf("Error Number % d\n", errno);
return 0;


Thus Input and Output system call program was executed Successfully

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