Terminal script to group files into folders - shell

Question

I have a directory of files. I want to group them together in batches into n directories.
So...
"MyFolder" has files A, B, C, D, E, F, G, H, I, J
I want to put them in to, say, 3 batches... batched like this:
Folder 1 - A, B, C, D
Folder 2 - E, F, G
Folder 3 - H, I, J
(and not like this... which is in only way I can work it out myself)
Folder 1 - A, D, G, J
Folder 2 - B, E, H
Folder 3 - C, F, I
Can anyone please advise me on how this can be done?
Thanks!

Answer 1

Here is a solution that uses the argument list (the only list available to POSIX shell without using advanced features from e.g. bash). Note the caveat; a sufficiently large number of files will not fit into the argument buffer. Also note that Stack Overflow incorrectly assumes $# (the length of the argument list) begins a comment, so the coloring is a bit off.
#!/bin/sh
num_folders=3 # default to 3 directories
if [ $# -gt 0 ]; then
num_folders=$1
shift
fi
# put all files into "argument" list
# (CAVEAT: this won't work on a dir with a LOT of files)
set - *
batch=$(( $# / $num_folders )) # files per folder
remainder=$(( $# % $num_folders )) # folders to get an "extra" file
i=1
while [ $i -le $num_folders ]; do
mkdir "Folder $i"
if [ $i -le $remainder ]
then j=0
else j=1
fi
while [ $j -le $batch ]; do
mv "$1" "Folder $i"
shift
j=$(( $j + 1 ))
done
i=$(( $i + 1 ))
done
Here is this script in action (I'm using # as a prompt to trigger a different color for commands vs output):
# touch A B C D E F G H I J
# ls *
A B C D E F G H I J
# sh ../batch-n.sh 3
# ls *
Folder 1:
A B C D
Folder 2:
E F G
Folder 3:
H I J
Here's what happens when n=4
# touch A B C D E F G H I J
# ls *
A B C D E F G H I J
# sh ../batch-n.sh 4
# ls *
Folder 1:
A B C
Folder 2:
D E F
Folder 3:
G H
Folder 4:
I J
I put this code in the parent directory (I therefore invoked it as ../batch-n.sh) because it would otherwise file itself. This will work just fine with files that have spaces in it, so long as they all fit into a single command (if ls * can't run, neither can this script).

Answer 2

Setup:
mkdir /tmp/so
cd /tmp/so
touch {A..Z} # create 26 files
Simplest thing that would work:
Live On Coliru
for a in Folder\ {1..8}; do mkdir -pv "$a"; read z y x w; mv -v "$z" "$y" "$x" "$w" "$a/"; done < <(ls ? | xargs -n4)
Or, prettier:
for a in Folder\ {1..8};
do mkdir -pv "$a"
read z y x w
mv -v "$z" "$y" "$x" "$w" "$a/"
done < <(ls ? | xargs -n4)
Alternatively, (slightly better with names containing whitespace)
for a in Folder\ {1..8}; do mkdir -pv "$a"; read z && read y && read x && read w; mv -v "$z" "$y" "$x" "$w" "$a/"; done < <(ls ?)