perl symlink immediate target

Question

I am looking for simple & proper way to obtain absolute path of symlink's immediate target (not final target), in perl.

My Example Tree:

|-- dir1
|   |-- link1 -> ../dir2/link2
|-- dir2
|   `-- link2 -> ../dir3/file.txt
|-- dir3
|   `-- file.txt
`-- test
    `-- script.pl

Code1:

my $link = dirname($ARGV[0]).'/'.readlink($ARGV[0]); 
print rel2abs($link), "\n";

Cmd: ./script.pl ../dir1/link1

Result: /tmp/perl_script_test/test/../dir1/../dir2/link2

Expected: /tmp/perl_script_test/dir2/link2

I am looking for absolute path of symlink's immediate target without ../

I tried abs_path(), realpath() but they all give path to final target (file.txt)

Is there any build-in function that does what I want to do I need to split the path and do manual concatenation ?

--

Mohan G

Answer 1

File::Path's absolute doesn't do any file system checks.

use File::Path qw( file );

my $link_qfn = file(...);

my $link_dir_qfn = $link_qfn->dir;
my $target_qfn   = $link_dir_qfn->file(readlink($link_qfn));
my $target_fqfn  = $target_qfn->absolute;

say $target_fqfn;

Say the CWD is /tmp/perl_script_test/test

$link_qfn     ../dir1/link1
$link_dir_qfn ../dir1
$target_qfn   ../dir1/../dir2/link2
$target_fqfn  /tmp/perl_script_test/test/../dir1/../dir2/link2

Say the CWD is /tmp/perl_script_test

$link_qfn     dir1/link1
$link_dir_qfn dir1
$target_qfn   dir1/../dir2/link2
$target_fqfn  /tmp/perl_script_test/dir1/../dir2/link2

---

You've added to the following to your question:

I am looking for absolute path of symlink's immediate target without ../

You can't safely do that without possibly resolving symlinks. For example,

/tmp/perl_script_test/dir1/../dir2/link2

is not necessarily equivalent to

/tmp/perl_script_test/dir2/link2

because

/tmp/perl_script_test/dir1 

could be a symlink.

---

The following might be sufficient for you:

use Cwd        qw( real_path );
use File::Path qw( dir file );

my $link_qfn = file(...);

my $link_dir_qfn    = $link_qfn->dir;
my $target_qfn      = $link_dir_qfn->file(readlink($link_qfn));
my $target_fn       = $target_qfn->basename;
my $target_dir_qfn  = $target_qfn->dir;
my $target_dir_fqfn = dir(real_path($target_dir_qfn));
my $target_fqfn     = $target_dir_fqfn->file($target_fn);

say $target_fqfn;

Say the CWD is /tmp/perl_script_test/test

$link_qfn        ../dir1/link1
$link_dir_qfn    ../dir1
$target_qfn      ../dir1/../dir2/link2
$target_fn       link2
$target_dir_qfn  ../dir1/../dir2
$target_dir_fqfn /tmp/perl_script_test/dir2
$target_fqfn     /tmp/perl_script_test/dir2/link2

You will only get the above output if none of the following are symlinks:

/tmp
/tmp/perl_script_test
/tmp/perl_script_test/test
/tmp/perl_script_test/dir1
/tmp/perl_script_test/dir2

(You could make it work even if the first two are symlinks, but that would take even more work.)