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9.3. Copying or Moving a File

9.3.1. Problem

You need to copy a file, but Perl has no
built-in copy function.

9.3.2. Solution

Use the copy function from the standard File::Copy
module:

use File::Copy;
copy($oldfile, $newfile);

You can do it by hand:

open(IN,  "<", $oldfile)   or die "can't open $oldfile: $!";
open(OUT, ">", $newfile)or die "can't open $newfile: $!";
$blksize = (stat IN)[11] || 16384;
# preferred block size?
while (1) {
$len = sysread IN, $buf, $blksize);
if (!defined $len) {
next if $! =~ /^Interrupted/;
# ^Z and fg on EINTR
die "System read error: $!\n";
}
last unless $len;
$offset = 0;
while ($len) { # Handle partial writes.
defined($written = syswrite OUT, $buf, $len, $offset)
or die "System write error: $!\n";
$len    -= $written;
$offset += $written;
};
}
close(IN);
close(OUT);

or you can call your system's copy program:

system("cp $oldfile $newfile"); # unix
system("copy $oldfile $newfile");     # dos, vms

9.3.3. Discussion

The File::Copy
module provides copy and move
functions. These are more convenient than resorting to low-level I/O
calls and more portable than calling system. This
version of move works across file-system
boundaries; the standard Perl built-in rename
(usually) does not.

use File::Copy;
copy("datafile.dat", "datafile.bak")
or die "copy failed: $!";
move("datafile.dat", "datafile.new")
or die "move failed: $!";

Because these functions return only a simple success status, you
can't easily tell which file prevented the copy or move from working.
Copying the files manually lets you pinpoint which files didn't copy,
but it fills your program with complex sysread s
and syswrite s.

9.3.4. See Also

Documentation for the standard File::Copy module (also in Chapter 32
of Programming Perl); the
rename, read, and
syswrite functions in
perlfunc(1) and in Chapter 29 of
Programming Perl