Split a folder with huge number of files in n folders


 
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# 1  
Old 06-22-2014
Split a folder with huge number of files in n folders

We have a folder XYZ with large number of files (>350,000). how can i split the folder and create say 10 of them XYZ1 to XYZ10 with 35,000 files each. (doesnt matter which files go where).
# 2  
Old 06-22-2014
Try something like:
Code:
cd XYZ || { echo "directory does not exist" > &2; exit 1 ;}
n=0
for i in *
do
  if [ $((n+=1)) -gt 10 ]; then
    n=1
  fi
  todir=../XYZ$n
  [ -d "$todir" ] || mkdir "$todir" 
  mv "$i" "$todir" 
done

Try it out on a test directory first and/or prepend echo to the mv command to see if it works as desired...

Last edited by Scrutinizer; 06-22-2014 at 05:00 PM..
This User Gave Thanks to Scrutinizer For This Post:
# 3  
Old 06-22-2014
Thanks. I have something similar. But I was wondering if there is a way to do this without the explicit loop and moving one file at a time. This is too slow and we have to perform this operation on multiple folders of the given size.



Quote:
Originally Posted by Scrutinizer
Try something like:
Code:
cd XYZ
n=0
for i in *
do
  if [ $((n+=1)) -gt 10 ]; then
    n=1
  fi
  todir=../XYZ$n
  [ -d "$todir" ] || mkdir "$todir" 
  mv "$i" "$todir" 
done

Try it out on a test directory first and/or prepend echo to the mv command to see if it works as desired...
# 4  
Old 06-22-2014
What OS are you using?

Do any of the 350,000 files you're moving have names that contain any space, tab, or newline characters?
# 5  
Old 06-22-2014
Aren't 350 000 files too many arguments for for i in *?
Safer and faster is
Code:
find . -type f |
while read i

This User Gave Thanks to MadeInGermany For This Post:
# 6  
Old 06-22-2014
Quote:
Originally Posted by Don Cragun
What OS are you using?

Do any of the 350,000 files you're moving have names that contain any space, tab, or newline characters?
Hi Don,

I am on Ubuntu Server 12.04 LTS. The files do not contain any special characters except _

Actually the format is something like

<xyz>_n1_n2_n3.pbx

where <xyz> is a prefix containing only alphabets [a-z A-Z]
n1 is a number less than 10
n2 is a number less than 1000
n3 is a number less than 10000
pbx is the extension

---------- Post updated at 04:08 PM ---------- Previous update was at 04:06 PM ----------

Quote:
Originally Posted by MadeInGermany
Aren't 350 000 files too many arguments for for i in *?
Safer and faster is
Code:
find . -type f |
while read i

Thanks.. Although I did not get an error for too many files with for I in *, find seems faster and as you mentioned safer if the number of files increase.
# 7  
Old 06-22-2014
Quote:
Originally Posted by MadeInGermany
Aren't 350 000 files too many arguments for for i in *?
Safer and faster is
Code:
find . -type f |
while read i

In theory, no. The for i in * is all processed inside the shell without having to create an argument list like it would for ls * (which would almost certainly fail hitting ARG_MAX limits).

Another possibility would be something like set -- * which would then allow you to use $# to split groups of files instead of going round-robin. Invoking mv for each file to be moved is going to be much slower than invoking mv to move groups of files.

If filenames are of the form <xyz>_n1_n2_n3.pbx would it make more sense to create a directory for each n2 value rather than ten directories with an arbitrary spread of files into those new directories. If part of the filename can be used to determine which directory to search, it should make it much faster to find needed files after the files have been rearranged. If this is of interest to the submitter, we could help come up with a way to help do this.
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