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How to Get directory time stamp in c++

Hi, I am new to both C++ and Linux. I am working on a license key generator. One of the unique characteristics that we are going to grab off of a linux machine is the datestamp of when /bin was created. I would like the date as a long. Is there an easy way to do this?
Please help!
thank you very much in advance.

Probably the easiest way is with "stat":

Code:

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

...



  struct stat st;

  int ierr = stat ("/bin", &st);

  if (ierr != 0)

    << error handling >>

  unsigned long date = (unsigned long)stat.st_mtime;

  ...

You can easily find more with "man stat" (from a command prompt) or Google for "Linux struct stat" code examples.

'Hope that helps .. PSM

Hi, thank you for the quick response. I tried running the code you gave me..
This is what I am running currently:

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <iostream>

int main()
{
struct stat st;
int ierr = stat ("/bin", &st);
if (ierr != 0) {
std::cout << "errori\n";
}
unsigned long date = (unsigned long) stat.st_mtime;
std::cout << "date = " << date << "\n";
}

There error i get when i compile (w/ g++ in a terminal shell) is
craig.cpp:13: error: request for member 'st_mtim' in 'stat', which is of non-class type 'int ()(const char*, stat*)throw ()'

I thought maybe it was a cast problem, but I tried changing to int w/ no luck. I checked the man entry but didn't see much info. thanks again

Quote:

Originally Posted by craigorymaas (Post 3510171)

The person who suggested the code used 'st_mtime', the error message for some reason says 'st_mtim'.

I'd suggest to start from this discrepancy.

craigorymaas -

"The person who suggested you start with the discrepency" is correct.

Here's sample code:

Code:

#include <stdio.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>



#define BIN_DIR "/bin"



int

main (int argc, char *argv[])

{

  struct stat st;

  int ierr = stat (BIN_DIR, &st);

  if (ierr != 0)

  {

    printf("Sorry: couldn't find %s: ierr= %d\n", BIN_DIR, ierr);

    return 1;

  }

  printf (

    "dev_t      st_dev:    %lu  /* device */\n"

    "ino_t      st_ino:    %lu  /* inode */\n"

    "mode_t    st_mode:    %lu  /* protection */\n"

    "nlink_t    st_nlink:  %lu  /* number of hard links */\n"

    "uid_t      st_uid:    %lu  /* user ID of owner */\n"

    "gid_t      st_gid:    %lu  /* group ID of owner */\n"

    "dev_t      st_rdev:    %lu  /* device type (if inode device) */\n"

    "off_t      st_size:    %lu  /* total size, in bytes */\n"

    "blksize_t  st_blksize: %lu  /* blocksize for filesystem I/O */\n"

    "blkcnt_t  st_blocks:  %lu  /* number of blocks allocated */\n"

    "time_t    st_atime:  %lu  /* time of last access */\n"

    "time_t    st_mtime:  %lu  /* time of last modification */\n"

    "time_t    st_ctime:  %lu  /* time of last status change */\n",

    (unsigned long)st.st_dev,

    (unsigned long)st.st_ino,

    (unsigned long)st.st_mode,

    (unsigned long)st.st_nlink,

    (unsigned long)st.st_uid,

    (unsigned long)st.st_gid,

    (unsigned long)st.st_rdev,

    (unsigned long)st.st_size,

    (unsigned long)st.st_blksize,

    (unsigned long)st.st_blocks,

    (unsigned long)st.st_atime,

    (unsigned long)st.st_mtime,

    (unsigned long)st.st_ctime);

  return 0;

}

Quote:

gcc -Wall -g -o x x.c
./x
dev_t st_dev: 770 /* device */
ino_t st_ino: 52 /* inode */
mode_t st_mode: 16877 /* protection */
nlink_t st_nlink: 2 /* number of hard links */
uid_t st_uid: 0 /* user ID of owner */
gid_t st_gid: 0 /* group ID of owner */
dev_t st_rdev: 0 /* device type (if inode device) */
off_t st_size: 2896 /* total size, in bytes */
blksize_t st_blksize: 4096 /* blocksize for filesystem I/O */
blkcnt_t st_blocks: 5 /* number of blocks allocated */
time_t st_atime: 1237848350 /* time of last access */
time_t st_mtime: 1160427118 /* time of last modification */
time_t st_ctime: 1160427118 /* time of last status change */

'Hope that helps - "The person who suggested the code that used st_mtime" ;-)

Thanks so much for the help. I haven't attempted to run the code yet, I will start in just a second but wanted to send a quick thanks first!

Ok, I added the extra import, etc. Changed my couts to printf, and now my error is
/tmp/ccqV0frA.o:(.eh_frame+0x11): undefined reference to `__gxx_personality_v0'

Oops.
OK, here is the error without smilies
gcc -o craig craig.cpp

/tmp/ccs3MTJB.o:(.eh_frame+0x11): undefined reference to `__gxx_personality_v0'

I've tried it w/ -Wall, -g, etc
All result in the same error. Has someone seen this before? Am I missing some imports or something?

OK, nm those last messages, it was just a c++ linking error. I compiled w/ g++ and everything was fine.

My concern now is that it is getting the mtime or the ctime, which are modified and changed, correct?
The time that I get absolutely has to be something that is not going to change, because it is for a unique key for a system. If these times change, then the key will cease to work. Are these times something that will change?

(thanks again!)

Hey paul,
I've been able to simply execute "touch bin", at which point the ctime, mtime, and atime all change from their previous values. I have read on some forums that linux actually does not save any "creation" time variables and that it is basically impossible to retrieve this information. I am ready to give up on this idea and chalk it up to impossible.

On a side note, I was able to get the first logins to the system with the function "last" called from command line. Do you know if this can also be stored in a struct? I have searched around but have been unable so far to find information.

Thanks again
Craig

There are lots of things you can use to identify a host as "unique".

Mac addresses and CPU IDs come immediately to mind.

You can also create your own "marker file", give it some unique stamp (write a GUID into it, perhaps).

'Hope that helps .. PSM