63

I need to find the creation time of a file, when I read some articles about this issue, all mentioned that there is no solution (like Site1, Site2).

When I tried the stat command, it states Birth: -.

So how can I find the creation time of a file?

  • 2
    Keep in mind that the 'creation time' of a file is not guaranteed to be accurate. There are many ways to 'fudge' the creation dates on a file. – Thomas Ward Nov 27 '17 at 15:00
  • @ThomasWard Many more than ways to fudge other file data? – Cees Timmerman Feb 9 at 6:21
66

There is a way to know the creation date of a directory , just follow these steps :

  1. Know the inode of the directory by ls -i command (lets say for example its X)

  2. Know on which partition your directory is saved by df -T /path command ( lets say its on /dev/sda1 )

  3. Now use this command : sudo debugfs -R 'stat <X>' /dev/sda1

You will see in the output :

crtime: 0x4e81cacc:966104fc -- mon Sep 27 14:38:28 2013

crtime is the creation date of your file .

What I tested :

  1. Created a directory at specific time .
  2. Accessed it .
  3. Modified it by creating a file .

  4. I tried the command and it gave an exact time .

  5. Then i modify it , and test again , the crtime remained the same , but modify and access time changed .
  • I post this , because i like to discuss so i can understand better , i am wonder why people say that Linux doesn't support this feature – nux May 21 '14 at 15:21
  • 13
    Because Linux itself does not. The ext4 filesystem does have this information but the kernel does not provide an API to access it. Apparently, debugfs extracts it directly from the filesystem so it does not need to use the kernel's API. See here. – terdon May 21 '14 at 15:31
  • I tested it. It worked perfectly on ext4 file system – Fahim Babar Patel Sep 21 '16 at 14:35
  • 1
    Seems like this is ext4 specific? It didn't work with XFS for me. – Quantum7 May 3 at 8:32
54

@Nux found a great solution for this which you should all upvote. I decided to write a little function that can be used to run everything directly. Just add this to your ~/.bashrc.

get_crtime() {

    for target in "${@}"; do
        inode=$(stat -c '%i' "${target}")
        fs=$(df  --output=source "${target}"  | tail -1)
        crtime=$(sudo debugfs -R 'stat <'"${inode}"'>' "${fs}" 2>/dev/null | 
        grep -oP 'crtime.*--\s*\K.*')
        printf "%s\t%s\n" "${target}" "${crtime}"
    done
}

Now, you can run get_crtime to print the creation dates of as many files or directories as you like:

$ get_crtime foo foo/file 
foo Wed May 21 17:11:08 2014
foo/file    Wed May 21 17:11:27 2014
  • Note that the creation date is not the creation date of the original file if the file is a copy (like it is with the modification date). Once a file is copied, the modification date is from the original, but the creation date is from the copy. (theres is some misunderstanding in this question: askubuntu.com/questions/529885/…) – Jacob Vlijm Sep 29 '14 at 10:57
  • 1
    @JacobVlijm well, yes, of course. Isn't that obvious? How could it be otherwise? A copy is a new file that just happens to have the same contents as another. The modification time also changes for a copy by the way. It is set to the moment the copy was created unless you explicitly choose for that not to happen using cp -p or similar. – terdon Sep 29 '14 at 12:42
  • Absolutely, but it at the same time, it wouldn't be that unlogical if, like the mod. date, somewhere in the file the date would be stored when it originated. I must admit I didn't know that was not the case until I answered the linked question. – Jacob Vlijm Sep 29 '14 at 12:45
  • Just tried by the way, I just copied files in nautilus, modification date stays as it is (was), m. date is earlier than creation date. – Jacob Vlijm Sep 29 '14 at 13:42
  • 1
    @demongolem yes, the CentOS version of df doesn't seem to support the --output option. In that case, you can replace that line with fs=$(df foo | awk '{a=$1}END{print a}' and the function will work as well. All I'm showing in this answer is a way to wrap the command from the accepted answer in a way that can be run directly for file/directory targets. – terdon Feb 24 '16 at 18:52
10

The inability of stat to show the creation time is due to limitation of the stat(2) system call, whose return struct didn't include a field for the creation time. Starting with Linux 4.11 (i.e., 17.10 and newer*), however, the new statx(2) system call is available, which does include a creation time in its return struct.

* And possibly on older LTS releases using the hardware enablement stack (HWE) kernels. Check uname -r to see if you are using a kernel at least at 4.11 to confirm.

Unfortunately, it's not easy to call system calls directly in a C program. Typically glibc provides a wrapper that makes the job easy, but glibc only added a wrapper for statx(2) in August 2018 (version 2.28, available in 18.10). Luckily, @whotwagner wrote a sample C program that shows how to use the statx(2) system call on x86 and x86-64 systems. Its output is the same format as stat's default, without any formatting options, but it's simple to modify it to print just the birth time.

First, clone it:

git clone https://github.com/whotwagner/statx-fun

You can compile the statx.c code, or, if you just want the birth time, create a birth.c in the cloned directory with the following code (which is a minimal version of statx.c printing just the creation timestamp including nanosecond precision):

#define _GNU_SOURCE
#define _ATFILE_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include "statx.h"
#include <time.h>
#include <getopt.h>
#include <string.h>

// does not (yet) provide a wrapper for the statx() system call
#include <sys/syscall.h>

/* this code works ony with x86 and x86_64 */
#if __x86_64__
#define __NR_statx 332
#else
#define __NR_statx 383
#endif

#define statx(a,b,c,d,e) syscall(__NR_statx,(a),(b),(c),(d),(e))

int main(int argc, char *argv[])
{
    int dirfd = AT_FDCWD;
    int flags = AT_SYMLINK_NOFOLLOW;
    unsigned int mask = STATX_ALL;
    struct statx stxbuf;
    long ret = 0;

    int opt = 0;

    while(( opt = getopt(argc, argv, "alfd")) != -1)
    {
        switch(opt) {
            case 'a':
                flags |= AT_NO_AUTOMOUNT;
                break;
            case 'l':
                flags &= ~AT_SYMLINK_NOFOLLOW;
                break;
            case 'f':
                flags &= ~AT_STATX_SYNC_TYPE;
                flags |= AT_STATX_FORCE_SYNC;
                break;
            case 'd':
                flags &= ~AT_STATX_SYNC_TYPE;
                flags |= AT_STATX_DONT_SYNC;
                break;
            default:
                exit(EXIT_SUCCESS);
                break;
        }
    }

    if (optind >= argc) {
        exit(EXIT_FAILURE);
    }

    for (; optind < argc; optind++) {
        memset(&stxbuf, 0xbf, sizeof(stxbuf));
        ret = statx(dirfd, argv[optind], flags, mask, &stxbuf);
        if( ret < 0)
        {
            perror("statx");
            return EXIT_FAILURE;
        }
        printf("%lld.%u\n", *&stxbuf.stx_btime.tv_sec, *&stxbuf.stx_btime.tv_nsec);
    }
    return EXIT_SUCCESS;
}

Then:

$ make birth
$ ./birth ./birth.c
1511793291.254337149
$ ./birth ./birth.c | xargs -I {} date -d @{}
Mon Nov 27 14:34:51 UTC 2017

In theory this should make the creation time more accessible:

  • more filesystems should be supported than just the ext* ones (debugfs is a tool for ext2/3/4 filesystems, and unusable on others)
  • you don't need root to use this (except for installing some required packages, like make and linux-libc-dev).

Testing out an xfs system, for example:

$ truncate -s 1G temp; mkfs -t xfs temp; mkdir foo; sudo mount temp foo; sudo chown $USER foo
$ touch foo/bar
$ # some time later
$ echo > foo/bar
$ chmod og-w foo/bar
$ ./birth foo/bar | xargs -I {} date -d @{}
Mon Nov 27 14:43:21 UTC 2017
$ stat foo/bar                             
  File: foo/bar
  Size: 1           Blocks: 8          IO Block: 4096   regular file
Device: 700h/1792d  Inode: 99          Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/ muru)      Gid: ( 1000/ muru)
Access: 2017-11-27 14:43:32.845579010 +0000
Modify: 2017-11-27 14:44:38.809696644 +0000
Change: 2017-11-27 14:44:45.536112317 +0000
 Birth: -

However, this didn't work for NTFS and exfat. I guess the FUSE filesystems for those didn't include the creation time.


If, or rather when, glibc adds support for the statx(2) system call, stat will follow soon and we'll be able to use the plain old stat command for this. But I don't think this will be backported to LTS releases even if they do get newer kernels. So, I don't expect stat on any current LTS release (14.04, 16.04 or 18.04) to ever print the creation time without manual intervention.

On 18.10, however, you can directly use the statx function as described in man 2 statx (note that the 18.10 manpage is incorrect in stating that glibc hasn't added the wrapper yet).

  • Thanks for linking to github. I searched a few months ago when 4.11 came out and didn't find anything and then forgot about it. – WinEunuuchs2Unix Nov 28 '17 at 0:34
  • @WinEunuuchs2unix forgive by pinging but would it be wise to ask on meta site why muru's account has a rep of just 1? – George Udosen Dec 23 '18 at 15:15
  • @GeorgeUdosen That is shocking! I have a hunch why though... – WinEunuuchs2Unix Dec 23 '18 at 15:52
  • @GeorgeUdosen There is a recent meta question about suspensions in general and they won't address a specific user: meta.askubuntu.com/questions/18341/… I'm going into chat room now so you can carry on conversation there if you wish. – WinEunuuchs2Unix Dec 23 '18 at 17:08
  • Now that the feature is available, would you know how to modify that field? I may try to create a ctypes wrapper to do it in python. Thanks. – Gringo Suave Feb 14 at 2:09
3

TL;DR: Just run: sudo debugfs -R 'stat /path/to/your/file' /dev/<your fs>

(To figure out your fs, run df -T /path/to/your/file, most likely it's going to be /dev/sda1).

Long version:

We are going to run two commands:

  1. Find out the name of partition name for your file.

    df -T /path/to/your/file
    

    The output is going to look like this (partition name is first):

    Filesystem     Type 1K-blocks    Used Available Use% Mounted on
    /dev/<your fs> ext4   7251432 3481272   3509836  50% /
    
  2. Find out creation time for that file.

    sudo debugfs -R 'stat /path/to/your/file' /dev/<your fs>
    

    In the output, look for ctime.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.