rename v mv function conflict

[Derick Centeno]

Thanks Geert:
Your explanation was pristinely humorous and instructive.  You included
details I've never seen in a man or info page AND your explanation was
CLEARER! 

I also learned that it's HOPELESS to ask open source programmers to
strictly maintain and follow LOGICAL PROCEDURES IN THE FUNCTIONS THEY
CREATE!! The poor God of Logic must be either laughing hysterically or
in tears; if it was up to Linux programmers He'd probably be both while
managing a state of depression by riding a roller coaster after having
had a pizza with sausages and hot tamales!

Thanks Geert for broadening my boundaries...I had mistakenly thought
that there was a science to all this open source effort as opposed to
the "Whatever Fits" approach of Rolling Stone or MAD magazine!  Yep, my
horizons have been expanded today... I should have known.  This open
source stuff is being written by hippies, yippies and their off-spring!
Of course, of course...I should have known and expected this.  Yellow
Submarine -- FOREVER.  Holes in ME pocket, indeed...OOh boy... sheeesh!

Thanks Geert, for this Zen Moment!
 
On Wed, 2004-09-15 at 05:35, Geert Janssens wrote:
> Derick Centeno wrote:
> > Hi Gang:
> > Has anyone else noticed a logical conflict between the rename and mv
> > functions?  Correcting this problem may be way beyond the scope of this
> > list but I was wondering if any of the luminaries here came up with a
> > solution to correct both of them.
> > 
> > For instance, although man and info regarding rename report the same
> > instructions.  When it is applied rename behaves as though it has
> > succeeded in its execution, when in fact it has failed!
> > 
> > mv has the capacity to rename anything but not only are they no
> > directions within man or info how to begin such a procedure -- no one
> > apparently has noticed the logical conflict of having one function do
> > the job of another.  In short, mv is working outside of its functional
> > scope; it may have been built that way but unlike the leaning Tower of
> > Pisa there is no value in this conflicting feature which properly should
> > be the function of rename.
> > 
> You have just discovered the prime rule for linux computing:
> "For every problem, there is at least one solution, but most likely 
> more" :-)
> 
> I can understand your confusion because of the names, but rename and mv 
> are designed with different goals in mind.
> 
> rename is designed to rename a large group of similarly named files, 
> while mv is a general purpose move/rename command.
> 
> For some actions, you can use either, because there is quite some 
> overlap in what they can do. I'll give you some examples.
> 
> If you only want to partly rename one single file, you can use either 
> command. For example to rename "kermit.frog" to "hermit.frog" you could use
> rename k h kermit.frog
> or
> mv kermit.frog hermit.frog
> 
> If you want to completely rename one single file, you could still use 
> either command, but rename obviously gets less interesting, especially 
> if the old name is a rather long name. Take for example the rename of 
> "a_very_very_very_long.one" to "short.name":
> 
> rename a_very_very_very_long.one short.name a_very_very_very_long.one
> mv a_very_very_very_long.one short.name
> 
> You can start to see the pattern already:
> 
> rename takes at least three parameters:
> 1. the part of the filename you want to replace
> 2. what you would want to replace it with
> 3. the file that should be renamed
> 
> mv takes two parameters for a rename:
> 1. the old filename
> 2. the new filename
> 
> Depending on what you want to do, one or the other command is more 
> convenient.
> 
> And by the way, it doesn't matter if you are renaming files or 
> directories. It works with either:
> 
> mv old.directory new.directory
> does the same as
> rename old new old.directory
> 
> You start to think I'm a good magician already ?
> Then let's make things more confusing ;-) :
> Your reasoning is:
> rename's job should be renaming files, mv's job should be moving files 
> around.
> 
> As you correctly noticed, mv can also rename files. I'll show you now, 
> that 'rename' can also move files !
> 
> Suppose you have a file jolly.jumper in directory /home/farm/stable, and 
> you want to move it to directory /home/farm/meadow. This can be done by 
> either
> cd /home/farm
> mv stable/jolly.jumper meadow
> 
> or
> cd /home/farm
> rename stable meadow stable/jolly.jumper
> 
> Note that neither command renames directory stable to meadow, but both 
> actually move the file from one directory to the other !
> 
> Now that's magic, isn't it ? ;-)
> 
> Ok, I'll tell you my secret then.
> 
> To understand how all of this works, you should look at filenames as 
> starting from the root directory, so in the above example jolly.jumper's 
> real filename is actually /home/farm/stable/jolly.jumper.
> 
> So to move this file to another directory is actually the same a 
> renaming it, only this time it's not the last part that is changed, but 
> the part just before the last '/'.
> 
> There is only one limitation to this: you must move to an existing 
> directory. This is done to prevent that with a simple typo a file gets 
> moved into an unknown directory. Chances are you wouldn't find your file 
> anymore afterwards.
> 
> Remember: all of the above only shows the actions you can perform with 
> either command. However, although you can use both commands, depending 
> on the action, one or the other is simpler to use, because they use 
> other parameters.
> 
> 
> Apart from that, they both have actions the other command can't perform.
> 
> Some examples:
> Renaming many similarly named files is only possible with rename, or a 
> home-brewn shell script using mv.
> For example a whole directory containing several files ending in .html 
> should be renamed to files ending in .htm (this kind of conversions 
> could happen when working in a mixed linux-windows environment for example):
> rename .html .htm <directory>/*.html
> 
> mv has quite a lot of finetuning options in case the destination file 
> already exists: you could tune it to make a backup of the old 
> destination file:
> mv -b old.name new.name
> this will first rename the file new.name to new.name~ if it already 
> exists, and then rename old.name to new.name.
> 
> You could also have mv ask wether or not to overwrite files:
> mv -i old.name new.name
> 
> Or you could have mv only overwrite the file if the source filename is 
> newer:
> mv -u old.name new.name
> 
> 
> Hopefully this helps explaining things a bit.
> 
> Cheers,
> 
> Geert
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