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SubjectBUG: Is it a bug in Linux time() function or Linux OS calls?
Dear All,

I wrote a small program, that creates files at an interval of 1 minute. But the time at which the file is created and last written and the last modification time of the file as shown by ls command differs by 1 second. The code and the output is presented below. please let me know where could be the bug?

root@new:/home/srinivas# cat b.c
#include <time.h>
#include <stdio.h>
#include <sys/stat.h>
#include <dirent.h>
#include <fcntl.h>
int main ()
{
int fd;
int i=0;
time_t initial_time = time(NULL);
time_t interval = 60;
time_t curr_time = time(NULL);

fd=open ("test1.txt", O_WRONLY | O_CREAT | O_TRUNC, 0666);
write(fd,"abcd1",5);
while(1)
{
curr_time = time(NULL);
if(curr_time >= initial_time)
{
if(i==0)
{
close(fd);
printf("\ntime before test2.txt fileopen= %d\n", time(NULL));
fd=open ("test2.txt", O_WRONLY | O_CREAT | O_TRUNC, 0666);
write(fd,"abcd2",5);
printf("time after test2.txt filewrite= %d\n", time(NULL));
system("ls -l --time-style=+%s test2.txt");
initial_time += interval;
i=1;
}
else
{
close(fd);
printf("\ntime before test1.txt fileopen= %d\n", time(NULL));
fd=open ("test1.txt", O_WRONLY | O_CREAT | O_TRUNC, 0666);
write(fd,"abcd1",5);
printf("time after test1.txt filewrite= %d\n", time(NULL));
system("ls -l --time-style=+%s test1.txt");
initial_time += interval;
i=0;
}
}
usleep(1000);
}
return 0;
}
root@new:/home/srinivas# gcc b.c
root@new:/home/srinivas# ./a.out

time before test2.txt fileopen= 1268203133
time after test2.txt filewrite= 1268203133
-rw-r--r-- 1 root root 5 1268203133 test2.txt

time before test1.txt fileopen= 1268203193
time after test1.txt filewrite= 1268203193
-rw-r--r-- 1 root root 5 1268203192 test1.txt

time before test2.txt fileopen= 1268203253
time after test2.txt filewrite= 1268203253
-rw-r--r-- 1 root root 5 1268203252 test2.txt

time before test1.txt fileopen= 1268203313
time after test1.txt filewrite= 1268203313
-rw-r--r-- 1 root root 5 1268203312 test1.txt

time before test2.txt fileopen= 1268203373
time after test2.txt filewrite= 1268203373
-rw-r--r-- 1 root root 5 1268203372 test2.txt

root@new:/home/srinivas# ls -ltr --time-style=+%s
total 40
-rwxrwxrwx 1 root root 1095 1268202457 b.c
-rwxr-xr-x 1 root root 10300 1268202459 a.out
-rw-r--r-- 1 root root 5 1268203312 test1.txt
-rw-r--r-- 1 root root 5 1268203372 test2.txt
root@new:/home/srinivas#


Some system info:
===========
Linux new 2.6.24-19-server #1 SMP Wed Jun 18 14:44:47 UTC 2008 x86_64 GNU/Linux
Gnu C 4.2.4
Linux C Library 2.7
binutils 2.18.0.20080103
util-linux 2.13.1
Console-tools 0.2.3
Sh-utils 6.10
===========


With best regards,

Yours sincerely,
Srinivas Nayak

My Home page: http://www.mathmeth.com/sn/
My Blog: http://srinivas-nayak.blogspot.com


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