symbolic link and absolute path

joybee2015 has asked for the wisdom of the Perl Monks concerning the following question:

Hello and thanks for your help!
Here is the problem I have:

In /var/tmp, I have file1, file2 and flink and flink ->file1, I need to get the absolute path of file1, which is /var/tmp/file1 to compare it with string fp1, the problem is that I cant get absolute path, how to solve the issue?

#!/usr/bin/perl
my $lpath = /var/tmp/flink;
my $fp1 = /var/tmp/file1;
my $realpath =readlink($lpath); #which returns file1;
my $absolutepath = abs_path($realpath); #returns ~/perl/file1, where ~
+/perl is where my perl script is, not correct
if (-e $realpath) {
    print "$realpath exist\n";
}
else { 
    print "not exist\n"; #which is not true  
}
[download]

Should I parse the $realpath, if there is no "/" or if it starts with "./", get the directory path from $lpath?

Comment on symbolic link and absolute path Download Code

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Re: symbolic link and absolute path by ikegami (Patriarch) on Aug 07, 2017 at 20:39 UTC
In contradiction to what you claim, that code doesn't run. I'm going to assume you imported `abs_path` refers to `abs_path` from Cwd. `abs_path` takes a path relative to the current work directory and converts it into an absolute path. However, `readlink` returns a path that should be treated as relative to the directory in which the symbolic link is found. You could use a means of finding the absolute path that allows you to specify the base directory, but there's a simpler solution here: `my $absolutepath = abs_path($lpath);` [download]	[reply] [d/l] [select]
Re: symbolic link and absolute path by 1nickt (Canon) on Aug 07, 2017 at 20:53 UTC
You don't need `readlink`. Simply use `abs_path`. `$ cd /Users/nick $ echo 'hi' > /tmp/foo $ ln -s /tmp/foo ./foo $ perl -MCwd=abs_path -E 'say abs_path("./foo")' /private/tmp/foo $ perl -MCwd=abs_path -E 'say abs_path("/Users/nick/foo")' /private/tmp/foo` [download] The way forward always starts with a minimal test.	[reply] [d/l] [select]
Re^2: symbolic link and absolute path by joybee2015 (Novice) on Aug 09, 2017 at 05:26 UTC
Thanks ikegami and lnickt for the help. Using abs_path directly without readlink did solve the problem. And sorry for the bug in my program. I posted on the windows and I ran my code on linux. So I just typed the code here without checking. I indeed used Cwd qw(abs_path).	[reply]