How do I get a file's last modified time in Perl?

Question

Suppose I have a filehandle $fh. I can check its existence with -e $fh or its file size with -s $fh or a slew of additional information about the file. How can I get its last modified time stamp?

Answer 1

Calling the built-in function stat($fh) returns an array with the following information about the file handle passed in (from the perlfunc man page for stat):

  0 dev      device number of filesystem
  1 ino      inode number
  2 mode     file mode  (type and permissions)
  3 nlink    number of (hard) links to the file
  4 uid      numeric user ID of file's owner
  5 gid      numeric group ID of file's owner
  6 rdev     the device identifier (special files only)
  7 size     total size of file, in bytes
  8 atime    last access time since the epoch
  9 mtime    last modify time since the epoch
 10 ctime    inode change time (NOT creation time!) since the epoch
 11 blksize  preferred block size for file system I/O
 12 blocks   actual number of blocks allocated

Element number 9 in this array will give you the last modified time since the epoch (00:00 January 1, 1970 GMT). From that you can determine the local time:

my $epoch_timestamp = (stat($fh))[9];
my $timestamp       = localtime($epoch_timestamp);

Alternatively, you can use the built-in module File::stat (included as of Perl 5.004) for a more object-oriented interface.

And to avoid the magic number 9 needed in the previous example, additionally use Time::localtime, another built-in module (also included as of Perl 5.004). Together these lead to some (arguably) more legible code:

use File::stat;
use Time::localtime;
my $timestamp = ctime(stat($fh)->mtime);

Answer 2

Use the builtin stat function. Or more specifically:

my $modtime = (stat($fh))[9]

Answer 3

my @array = stat($filehandle);

The modification time is stored in Unix format in $array[9].

Or explicitly:

my ($dev, $ino, $mode, $nlink, $uid, $gid, $rdev, $size,
    $atime, $mtime, $ctime, $blksize, $blocks) = stat($filepath);

  0 dev      Device number of filesystem
  1 ino      inode number
  2 mode     File mode  (type and permissions)
  3 nlink    Number of (hard) links to the file
  4 uid      Numeric user ID of file's owner
  5 gid      Numeric group ID of file's owner
  6 rdev     The device identifier (special files only)
  7 size     Total size of file, in bytes
  8 atime    Last access time in seconds since the epoch
  9 mtime    Last modify time in seconds since the epoch
 10 ctime    inode change time in seconds since the epoch
 11 blksize  Preferred block size for file system I/O
 12 blocks   Actual number of blocks allocated

The epoch was at 00:00 January 1, 1970 GMT.

More information is in stat.

Answer 4

You need the stat call, and the file name:

my $last_mod_time = (stat ($file))[9];

Perl also has a different version:

my $last_mod_time = -M $file;

but that value is relative to when the program started. This is useful for things like sorting, but you probably want the first version.

Answer 5

If you're just comparing two files to see which is newer then -C should work:

if (-C "file1.txt" > -C "file2.txt") {
{
    /* Update */
}

There's also -M, but I don't think it's what you want. Luckily, it's almost impossible to search for documentation on these file operators via Google.

Answer 6

You could use stat() or the File::Stat module.

perldoc -f stat

Answer 7

I think you're looking for the stat function (perldoc -f stat)

In particular, the item found at index 9 of the returned list (i.e., the 10th field) is the last modify time of the file, in seconds since the epoch.

So:

my $last_modified = (stat($fh))[9];

Answer 8

On my FreeBSD system, stat just returns a bless.

$VAR1 = bless( [
                 102,
                 8,
                 33188,
                 1,
                 0,
                 0,
                 661,
                 276,
                 1372816636,
                 1372755222,
                 1372755233,
                 32768,
                 8
               ], 'File::stat' );

You need to extract mtime like this:

my @ABC = (stat($my_file));

print "-----------$ABC['File::stat'][9] ------------------------\n";

or

print "-----------$ABC[0][9] ------------------------\n";

Answer 9

This is very old thread, but I tried using the solution and could not get the information out of File::stat. (Perl 5.10.1)

I had to do the following:

my $f_stats = stat($fh);
my $timestamp_mod = localtime($f_stats->mtime);
print "MOD_TIME = $timestamp_mod \n";

Just thought I share in case anyone else had the same trouble.

Answer 10

Another alternative is: $^T - (-M $fh)*3600*24

Given that the OP asked about the -X builtin functions I thought this might be along the lines of what he was looking for. I prefer it to stat() in some circumstances myself, tho I'm not sure I could defend that stylistic decision...

This uses the fact that Perl maintains the script start time in $^T (perldoc perlvar for more details), and that -M returns the delta of that vs the mod time of the file, as a floating point fraction of a day. It is cryptic but very perlish and fits nicely in situations where you don't have a file handle already (-X can operate on a file path or filehandle).

p.s. I used to have trouble finding details on the -X builtins, until realized you can find the details with perldoc -f -X in most perl-enabled command-line environments.