CentOS - Dec 2014 - get /full/path/filename.ext from filename.ext

This should be simple, but it's not, unless I'm forgetting something.

Writing a script, an arg is a filename.  So

fname=$1

But I want that expanded to include the full path and filename, not just 
what is given as the arg on the command line.

E.g., if the user's cwd is /home/joe/a/b/c/ and he specifies

../x/file-a.ext

then the function/utility should transform that into the absolute path 
with filename:

/home/joe/a/b/x/file-a.ext

In the simplest scenario, the answer would be $PWD/file-a.ext, but that 
would by no means cover a portion of the possible scenarios.

You'd think this functionality would be included already in one or 
another linux utility.  It's kinda like the complement to the
'basename'
utility.  I've looked into the dark corners of ls, stat, file, bash, 
type, find, and a few other linux standards, but nothing seems to do this.

Any gurus out there know the utility which does this?

On Tue, Dec 09, 2014 at 03:57:03PM -0500, ken wrote:
> You'd think this functionality would be included already in one or
> another linux utility.  It's kinda like the complement to the
> 'basename' utility.  I've looked into the dark corners of ls,
stat,
> file, bash, type, find, and a few other linux standards, but nothing
> seems to do this.
'readlink -f FILE'

The -f (or --canonicalize) follows symlinks and prints the canonical
path.

-- 
Jonathan Billings <billings at negate.org>

On 12/09/2014 08:11 PM, Jonathan Billings wrote:
> On Tue, Dec 09, 2014 at 03:57:03PM -0500, ken wrote:
>> You'd think this functionality would be included already in one or
>> another linux utility.  It's kinda like the complement to the
>> 'basename' utility.  I've looked into the dark corners of
ls, stat,
>> file, bash, type, find, and a few other linux standards, but nothing
>> seems to do this.
>
> 'readlink -f FILE'
>
> The -f (or --canonicalize) follows symlinks and prints the canonical
> path.
>
Perfect!  Thanks!!!

I don't know if this is of interest as an alternative.

I did find a cool functionality called locate  and updatedb
Updatedb creates the database of your files, locate does superfast searches.

It essentially does a superfast "find" on your root filesystem, giving
you the fully qualified path of all hits.
You can create db's on your other filessytems.

The problem is that it can get stale, but you can update it before doing 
your searches. Plus it gives you a fully qualified path name with the 
results.

So if you need to do a set of searches on a filesystem (or whole system)

run updatedb on each target filesystem to create the db for that filesystem.
then use locate to search each filesystem "db"...
it takes seconds like ls instead of minutes like find....the more files 
in the FS, the quicker the searches compared to other tools.

the best part is you can run the db's when your systems are quiet, and 
the databases use minimal diskspace.


On 12/9/2014 2:57 PM, ken wrote:
> This should be simple, but it's not, unless I'm forgetting
something.
>
> Writing a script, an arg is a filename.  So
>
> fname=$1
>
> But I want that expanded to include the full path and filename, not 
> just what is given as the arg on the command line.
>
> E.g., if the user's cwd is /home/joe/a/b/c/ and he specifies
>
> ../x/file-a.ext
>
> then the function/utility should transform that into the absolute path 
> with filename:
>
> /home/joe/a/b/x/file-a.ext
>
> In the simplest scenario, the answer would be $PWD/file-a.ext, but 
> that would by no means cover a portion of the possible scenarios.
>
> You'd think this functionality would be included already in one or 
> another linux utility.  It's kinda like the complement to the 
> 'basename' utility.  I've looked into the dark corners of ls,
stat,
> file, bash, type, find, and a few other linux standards, but nothing 
> seems to do this.
>
> Any gurus out there know the utility which does this?
>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos

On 2014-12-10, Dan Hyatt <dhyatt at dsgmail.wustl.edu>
wrote:
> I don't know if this is of interest as an alternative.
It may or may not be, but it doesn't help the OP, who already knows
where the file is, and just wants the full absolute path.  locate will
not help him there, especially if there are multiple files with the same
filename.ext on that filesystem.
> I did find a cool functionality called locate  and updatedb
locate has been around for many many years, certainly since at least
CentOS 4, likely much earlier.
> The problem is that it can get stale, but you can update it before doing 
> your searches.
There is (or at least, there should be) a script in /etc/cron.daily 
which updates it nightly.
> So if you need to do a set of searches on a filesystem (or whole system)
> run updatedb on each target filesystem to create the db for that
filesystem.
You can configure locate (in /etc/updatedb.conf) with which directories
to index or not index.  Then you do not need to maintain your own
indexes, you can simply use the single system index.

--keith

-- 
kkeller at wombat.san-francisco.ca.us

On 12/10/2014 04:02 PM, Dan Hyatt wrote:
> I don't know if this is of interest as an alternative.
>
> I did find a cool functionality called locate  and updatedb
> Updatedb creates the database of your files, locate does superfast
> searches.
>
> It essentially does a superfast "find" on your root filesystem,
giving
> you the fully qualified path of all hits.
> You can create db's on your other filessytems.
>
> The problem is that it can get stale, but you can update it before doing
> your searches. Plus it gives you a fully qualified path name with the
> results.
>
> So if you need to do a set of searches on a filesystem (or whole system)
>
> run updatedb on each target filesystem to create the db for that
> filesystem.
> then use locate to search each filesystem "db"...
> it takes seconds like ls instead of minutes like find....the more files
> in the FS, the quicker the searches compared to other tools.
>
> the best part is you can run the db's when your systems are quiet, and
> the databases use minimal diskspace.
Dan,

Thanks for responding.  I've been using those two utilities for a long 
time, and they are indispensable.  But they don't solve the issue I'm 
having.  Consider the case where there are multiple files with the same 
name but different paths.  Also, it takes quite a while for the data 
used by those utilities to update, much too long for an interactive script.

>
>
> On 12/9/2014 2:57 PM, ken wrote:
>> This should be simple, but it's not, unless I'm forgetting
something.
>>
>> Writing a script, an arg is a filename.  So
>>
>> fname=$1
>>
>> But I want that expanded to include the full path and filename, not
>> just what is given as the arg on the command line.
>>
>> E.g., if the user's cwd is /home/joe/a/b/c/ and he specifies
>>
>> ../x/file-a.ext
>>
>> then the function/utility should transform that into the absolute path
>> with filename:
>>
>> /home/joe/a/b/x/file-a.ext
>>
>> In the simplest scenario, the answer would be $PWD/file-a.ext, but
>> that would by no means cover a portion of the possible scenarios.
>>
>> You'd think this functionality would be included already in one or
>> another linux utility.  It's kinda like the complement to the
>> 'basename' utility.  I've looked into the dark corners of
ls, stat,
>> file, bash, type, find, and a few other linux standards, but nothing
>> seems to do this.
>>
>> Any gurus out there know the utility which does this?
>>
>> _______________________________________________
>> CentOS mailing list
>> CentOS at centos.org
>> http://lists.centos.org/mailman/listinfo/centos
>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos