Renaming Groups of Files From the Command Line

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Trying to figure how the command works

Anonymous's picture

Enjoyed the video

I can see the removal of the parts, but not the re-arrangement.

Ok, finally figured out the following:
1) The command uses "substring removal" / "parameter substitution". Took awhile to find this out - my first search term was " ${f# " and got stuff on F# prog language. Live and Learn.
2) The " f# " is for removing the shortest prefix (ie, from the left).
3) The " f$ " is for removing the shortest prefix (ie, from the right).

Problem Restated:
1) Where in the command does it say ----> move the " aa " from the the beginning to the end of the filename?

Correction to the video
1) " f# " is for removing the shortest _not_ the longest prefix

Link that was helpful: Linux Journal Article

I really enjoy learning about the CLI:) and look forward to these videos.


Renaming Details

Mitch Frazier's picture

First, if I said "longest" I mis-spoke: "#" and "%" remove the "shortest" match, "##" and "%%" remove the longest match.

The rename command is this:

   mv -i $f 2009${f#*-2009}-${%-2009*}

There are 4 parts to the final file name:

   2009                # Literal
   ${f#*-2009}         # Based on original name
   -                   # Literal
   ${f%-2009*}         # Based on original name

Given the name "aa-2009-01-01". The first substitution removes the shortest prefix that matches "*-2009", in this case that prefix is "aa-2009", leaving "-01-01". The second substitution removes the shortest suffix that matches "-2009*", in this case that suffix is "-2009-01-01", leaving "aa". So the final name is formed from:

   2009                ==> 2009
   ${f#*-2009}         ==> -01-01
   -                   ==> -
   ${f%-2009*}         ==> aa

Resulting in the file name "2009-01-01-aa", the desired result.

Mitch Frazier is an Associate Editor for Linux Journal.


Anonymous's picture

I got it!
Very Clever
That was a surprisingly quick reply - Thanks


Ways's picture

rename 's/foo/bar/g' *

rename .oldextension .newextension *.oldextension

mmv 'banana_*_*.asc' 'banana_#2_#1.asc'

Bulk renaming :

You can also use "rename" command

apexwm's picture

The "rename" command offers as way to directly do essentially the same thing. It does a find/replace of the groups of files you specify.

Only in a few cases

Mitch Frazier's picture

Rename will work for you in some cases but not all, specifically it wouldn't work for the example in the video, unless I'm missing something...

Mitch Frazier is an Associate Editor for Linux Journal.

rename will work with

jimi's picture

rename will work with regex...

    rename s/\(..\)-\(.*\)/\$2-\$1/ *2009*

... but I never considered this usage of parameter substitution. Thanks!