I want to find out the creation date of a particular file on a Linux system. Not the modification date or access date, the creation date.
I have tried with ls -ltrh and stat filename but neither gives me what I need. What else can I do to get this information?
stat -c '%w' file on filesystems that store creation time.
Note that on Linux this requires coreutils 8.31, glibc 2.28 and kernel version 4.11 or newer.
The POSIX standard only defines three distinct timestamps to be stored for each file: the time of last data access, the time of last data modification, and the time the file status last changed.
Modern Linux filesystems, such as ext4, Btrfs, XFS (v5 and later) and JFS, do store the file creation time (aka birth time), but use different names for the field in question (crtime in ext4/XFS, otime in Btrfs and JFS). Linux provides the statx(2) system call interface for retrieving the file birth time for filesystems that support it since kernel version 4.11. (So even when creation time support has been added to a filesystem, some deployed kernels have not immediately supported it, even after adding nominal support for that filesystem version, e.g., XFS v5.)
As Craig Sanders and Mohsen Pahlevanzadeh pointed out, stat does support the %w and %W format specifiers for displaying the file birth time (in human readable format and in seconds since Epoch respectively) prior to coreutils version 8.31. However, coreutils stat uses the statx() system call where available to retrieve the birth time only since version 8.31.
Prior to coreutils version 8.31 stat accessed the birth time via the get_stat_birthtime() provided by gnulib (in lib/stat-time.h), which gets the birth time from the st_birthtime and st_birthtimensec fields of the stat structure returned by the stat() system call. While for instance BSD systems (and in extension OS X) provide st_birthtime via stat, Linux does not. This is why stat -c '%w' file outputs - (indicating an unknown creation time) on Linux prior to coreutils 8.31 even for filesystems which do store the creation time internally.
As Stephane Chazelas points out, some filesystems, such as ntfs-3g, expose the file creation times via extended file attributes.
stap to create your own kernel API. See example in answer here.
Commented
Oct 15, 2013 at 13:12
TLDR; Use stap ("SystemTap") to create your own kernel API. Demo of ext4 creation time extraction below.
You can extract the ext4 creation times on Fedora 19 systems. Here's mine:
$ uname -a
Linux steelers.net 3.11.1-200.fc19.i686.PAE #1 SMP Sat Sep 14 15:20:42 UTC 2013 i686 i686 i386 GNU/Linux
It's clear that the inodes on my ext4 partitions have the creation time. Here's a shell script that determines the inode associated with a filename and then augments the stat output with the creation time by using stap ("systemtap").
NB: This is just a demo and hugely inefficient since a kernel module is created, loaded, and unloaded for every execution. This is also probably very fragile as no error checking is performed. A proper kernel API would be preferable, but this script could be made much more efficient and read the creation times of multiple files/inodes.
[contents of stap_stat.sh]
#/bin/sh
my_inode_str=$(stat --printf="%i" $1)
stap - << end_of_stap_script
global my_offsetof
probe begin {
system("stat $1");
my_offsetof = &@cast(0,"struct ext4_inode_info")->vfs_inode;
}
probe kernel.function("ext4_getattr@fs/ext4/inode.c") {
probe_inode=\$dentry->d_inode;
if (@cast(probe_inode, "struct inode")->i_ino == $my_inode_str) {
my_i_crtime = &@cast(probe_inode - my_offsetof,"struct ext4_inode_info")->i_crtime;
printf("CrTime: %s GMT\n", ctime(@cast(my_i_crtime, "timespec")->tv_sec));
printf("CrTime (nsecs): %d\n", @cast(my_i_crtime, "timespec")->tv_nsec);
exit();
}
}
end_of_stap_script
Here's a demo:
$ ll testfile
ls: cannot access testfile: No such file or directory
$ touch testfile
$ ./stap_stat.sh testfile
File: ‘testfile’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: fd02h/64770d Inode: 4850501 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1001/ Rick) Gid: ( 1001/ Rick)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2013-09-28 06:17:04.221441084 -0400
Modify: 2013-09-28 06:17:04.221441084 -0400
Change: 2013-09-28 06:17:04.221441084 -0400
Birth: -
CrTime: Sat Sep 28 10:17:04 2013 GMT
CrTime (nsecs): 220441085
$ ll testfile
-rw-rw-r--. 1 Rick Rick 0 Sep 28 06:17 testfile
$ cat - >> testfile
Now is the time ...
$ ll testfile
-rw-rw-r--. 1 Rick Rick 20 Sep 28 06:18 testfile
$ ./stap_stat.sh testfile
File: ‘testfile’
Device: fd02h/64770d Inode: 4850501 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1001/ Rick) Gid: ( 1001/ Rick)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2013-09-28 06:17:04.221441084 -0400
Modify: 2013-09-28 06:18:33.684374740 -0400
Change: 2013-09-28 06:18:33.684374740 -0400
Birth: -
CrTime: Sat Sep 28 10:17:04 2013 GMT
CrTime (nsecs): 220441085
$ cat testfile
Now is the time ...
$ ./stap_stat.sh testfile
File: ‘testfile’
Size: 20 Blocks: 8 IO Block: 4096 regular file
Device: fd02h/64770d Inode: 4850501 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1001/ Rick) Gid: ( 1001/ Rick)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2013-09-28 06:19:12.199349463 -0400
Modify: 2013-09-28 06:18:33.684374740 -0400
Change: 2013-09-28 06:18:33.684374740 -0400
Birth: -
CrTime: Sat Sep 28 10:17:04 2013 GMT
CrTime (nsecs): 220441085
$ mv testfile testfile2
$ ./stap_stat.sh testfile2
File: ‘testfile2’
Size: 20 Blocks: 8 IO Block: 4096 regular file
Device: fd02h/64770d Inode: 4850501 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1001/ Rick) Gid: ( 1001/ Rick)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2013-09-28 06:19:12.199349463 -0400
Modify: 2013-09-28 06:18:33.684374740 -0400
Change: 2013-09-28 06:20:45.870295668 -0400
Birth: -
CrTime: Sat Sep 28 10:17:04 2013 GMT
CrTime (nsecs): 220441085
$
debugfs + stat allow to get crtime without monkey patching the kernel.
In theory, with GNU stat you could use stat -c '%w' or %W to get a file's creation date (aka birthtime).
In practice, most filesystems do not record that information and the linux kernel does not provide any way of accessing it.
The closest you can get is the file's ctime, which is not the creation time, it is the time that the file's metadata was last changed.
Linux Weekly News had an interesting article about this a few years back - File creation times.
In ext4 it is possible; because ext4 file-system stores the file creation time. But still, you will find that the stat command is unable to show the date, because I think the kernel is not having any APIs for this.
Anyway, the file birth time is stored in ext4 and you can find it out, although not by a direct method, but by using debugfs
sudo debugfs -R "stat /ABSOLUTE/PATH" /dev/sdxX | grep crtime
/dev/sdxX is mounted in /some/path and the file is /some/path/some/file, the path to be specified is only some/file: its path must be referred not to the filesystem root, but to the mountpoint. Otherwise, the file won't be found.
In OS X you can use ls -lU, stat -f%B, GetFileInfo -d, or mdls -n kMDItemFSCreationDate:
$ ls -lU
total 0
-rw-r--r-- 1 lauri staff 0 Apr 25 03:58 a
$ stat -f%B a
1398387538
$ stat -f%SB -t %Y%m%d%H%M a
201404250358
$ GetFileInfo -d a
04/25/2014 03:58:58
$ mdls -n kMDItemFSCreationDate a
kMDItemFSCreationDate = 2014-04-25 00:58:58 +0000
stat --printf='%w' yourfile #human readable
stat --printf='%W' yourfile #seconds from Epoch , 0 if unknown
Difference between FreeBSD and GNU\Linux on stat command:
If you call stat command in GNU\Linux it invokes the -x option, but in FreeBSD, you yourself should invoke the -x option.
See also What file systems on Linux store the creation time?
Notes: --printf is very useful in scripting....!
Check this out:
# the last arg is the device to scan in.
debugfs -R 'stat /home/renich/somefile' /dev/sda1
BTW, this works on ext4 only. I haven't found a solution for BtrFS... yet ;)
I am using ubuntu, and most files are under ext4 file system, so we can ignore cases in other ones, like Btrfs, XFS (v5 and later) and JFS.
The standard ext4 Linux file system allocates space for a file-creation timestamp in its internal file system structures, but this hasn’t been implemented yet (I tried on Ubuntu 20.04)
Use this as an alternative:
stat --format='%z' {{YOUR_file}}
%z: time of last status change, human-readable. (aka ctime)
ctime: Changed timestamps, aren’t referring to changes made to the contents of a file. Rather, it’s the time at which the metadata related to the file was changed. File permission changes, for example, will update the changed timestamp.
atime v.s ctime v.s. mtime:
https://www.howtogeek.com/517098/linux-file-timestamps-explained-atime-mtime-and-ctime/
more about metadate of a file:
https://www.cs.columbia.edu/~smb/classes/s06-4118/l21.pdf
stat should work OOTB for showing creation time on ext4.
stat(1).stapto retrieve creation times.statstill works on the MacOS' APFS; e.g.stat -f "%m%t%SB %N" ./myfile.txt | cut -f2-