UNIX Shell: Find Out Real Path Of File or Directory

by on October 3, 2008 · 12 comments· LAST UPDATED March 8, 2013

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My programs and scripts needs a real path and not a a symbolic link. How to I determine a real path of any directory under Linux / UNIX like operating systems? How do I remove references to /./, /../ and extra '/' character in path?

To get physical path use realpath command. The realpath command uses the realpath() function to resolve all symbolic links, extra / characters and references to /./ and /../ in path. This is useful for shell scripting and security related applications.
Tutorial details
DifficultyEasy (rss)
Root privilegesNo
RequirementsBash/Ksh/Perl
Estimated completion timeN/A

Another option is readlink command to print value of a symbolic link or canonical file name.

Finally, you can use Perl or Python to print value of a symbolic link or canonical file name.

realpath examples

To resolve symbolic link, type:
$ realpath /home
Sample outputs:

/usr/home

To remove characters, run:
$ realpath /etc//apache/.
$ realpath ./foo
$ realpath /../some/where///./../path/

The realpath command included with most Linux distributions and UNIX like operating system such as FreeBSD. To install realpath under Debian / Ubuntu Linux, enter:
$ sudo apt-get install realpath

readlink command

Please note that mostly the same functionality is provided by the -f option of the readlink command:
$ readlink -f /home

Perl program example

Try the following Perl code for portability purpose under various Linux and Unix like oses:

 
#!/usr/bin/perl
use Cwd 'abs_path';
if (@ARGV != 2 ) {
  print "Usage: $0 --path file\n";
  exit;
}
$realfilepath = abs_path("$ARGV[1]");
print "$realfilepath\n";
 

Sample outputs:

Fig.01: Perl program in action

Fig.01: Perl program in action

Recommended readings:
  • man pages: readlink and realpath
  • To see Cwd document type: perldoc Cwd
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{ 12 comments… read them below or add one }

1 yoander October 23, 2008 at 9:08 pm

I cant’t find realpath in CentOS. Coud you address me?

Reply

2 nixCraft October 23, 2008 at 9:51 pm

Use readlink -f /path/to/file/or/dir command under RHEL / CentOS.

Reply

3 yoander October 23, 2008 at 10:07 pm

Thanks!!!

Reply

4 andy October 24, 2008 at 6:19 am

why you dont use the command
pwd -P
comes out of the box…

Reply

5 olexiy July 24, 2009 at 11:59 pm

pwd -P
works for folders only
if you have file as link to different file pwd -P will not help

Reply

6 Anthony Thyssen March 8, 2013 at 5:34 am

realpath and even reallink are NOT generally available on all linux machines (most unusual). It is certainally not available on solaris or other OS’s.

And yet the C library provides a “realpath” function, it is just not generally available to shell scripts. And my shell scripts generally have to deal with multiple OS environments.

So lets repeat the question…

How can you get the real path of a file with all symbolic links resolved on MOST unix operating systems. Is some special switch to some command available? Is there a drop in shell function that can be used?

Reply

7 Anthony Thyssen March 8, 2013 at 5:35 am

or even a perl function!

Reply

8 nixCraft March 8, 2013 at 8:35 am

Try:

#!/usr/bin/perl
use Cwd 'abs_path';
if (@ARGV != 2 ) {
  print "Usage: $0 --path file\n";
  exit;
}
$realfilepath = abs_path("$ARGV[1]");
print "$realfilepath\n";

Run it as:

./myrealpath.pl --path /foo/bar
./myrealpath.pl --path ../foo/bar
./myrealpath.pl --path ~/bar
./myrealpath.pl --path /path/to/dir

Reply

9 Anthony Thyssen March 12, 2013 at 1:52 am

thanks…

Reply

10 Leif June 28, 2013 at 3:22 pm

alias realpath=’perl -we ‘\”use Cwd; print Cwd::abs_path($_), “\n” foreach @ARGV;’\’

Reply

11 A November 6, 2013 at 12:39 pm

abs_path=`(cd .; pwd)`

Reply

12 A November 7, 2013 at 5:22 am

Let me correct myself; the following is the right solution that’ll always work:

abs_path=`(cd \`dirname $0\`; pwd)`

Reply

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