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

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);

Use the builtin stat function. Or more specifically:

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

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.

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.

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.

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

perldoc -f stat

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];