How do I segregate multiple files based on file size into a sub directory?

I have a bunch of video files which I would like to segregate based on file size I have decided.

Example:

Folder BB has 15 files of various file size.

I have sub folder set as:

1. less than 100 MB -- folder A
2. 100 MB to 500 MB -- folder B
3. more than 500 MB -- folder C

So instead of manually doing it can it be done via Bash or a script.

I have a general idea that find command and a proper if else would work, but have no idea how to script it.

Anyway, a general programming frame would be:

float _size=[file_size]; // Reads the file size

if(_size<100)    // File size is less than 100 MB
  {  exec mv [file] /A/* ; // Move to folder A }
else if(_size>500) // File size is greater than 500 MB
  {  exec mv [file] /C/* ; // Move to folder C }
else if((_size<=500)||(_size>=100)) //file size is between 100 to 500
  {  exec mv [file] /B/* ; // Move to folder C}
else
  {print("file error");}

So I hope it is easy to do. The above was just a general idea I would have done.

I suggest to loop over all files in the current directory with this for loop:

for i in *; do
  size=$(stat --printf="%s" "$i")
  if [ $size -lt 100000000 ]; then
      mv "$i" A/
  elif [ $size -lt 500000000 ]; then
      mv "$i" B/
  else
      mv "$i" C/
  fi
done

You requested Megabyte, if you actually wanted 100/500 Mebibyte use 104857600 and 524288000 accordingly.

If the directory contains other files and you just want to process e.g. .avi files, use:

for i in *.avi; do …

Explanations

• for i in *; do … ; done – loop over all files in the current directory
• size=$(stat --printf="%s" "$i") – get the file size in bytes using stat and save it as variable size
• if A; then B; elif C; then D; else E; fi – if A is true do B, else if C is true do D, else do E
• [ $size -lt X ] – test whether size is less than X
• mv "$i" Y/ – move the currently processed file inside folder Y

You can do this kind of thing with GNU find e.g.

find BB/ -type f \( -size -100M -exec mv -t A/ {} + \
  -o -size +500M -exec mv -t C/ {} + -o -exec mv -t B/ {} + \)

NOTES:

• If you want to move files within the same tree (e.g. A/, B/, C/ are subdirectories of BB) then you will need to prevent find from recursing into these, using -maxdepth or -prune for example.

• Care is required due to the rounding behavior of -size. It's not a problem with this case, but for example -size -1M will round all files smaller than 1024kB up to 1M such that only empty files match.

Testing with kilobyte sized files for convenience:

$ tree -h somepath/
somepath/
├── [   0]  file0
├── [100K]  file100
├── [150K]  file150
├── [200K]  file200
├── [250K]  file250
├── [300K]  file300
├── [350K]  file350
├── [400K]  file400
├── [450K]  file450
├── [ 50K]  file50
├── [500K]  file500
├── [550K]  file550
└── [600K]  file600

0 directories, 13 files

then

$ find somepath/ -type f \( -size -100k -exec mv -vt A/ {} + \
>   -o -size +500k -exec mv -vt C/ {} + -o -exec mv -vt B/ {} + \)
'somepath/file50' -> 'A/file50'
'somepath/file0' -> 'A/file0'
'somepath/file550' -> 'C/file550'
'somepath/file600' -> 'C/file600'
'somepath/file250' -> 'B/file250'
'somepath/file200' -> 'B/file200'
'somepath/file100' -> 'B/file100'
'somepath/file300' -> 'B/file300'
'somepath/file500' -> 'B/file500'
'somepath/file350' -> 'B/file350'
'somepath/file450' -> 'B/file450'
'somepath/file400' -> 'B/file400'
'somepath/file150' -> 'B/file150'

giving

$ tree -h A B C
A
├── [   0]  file0
└── [ 50K]  file50
B
├── [100K]  file100
├── [150K]  file150
├── [200K]  file200
├── [250K]  file250
├── [300K]  file300
├── [350K]  file350
├── [400K]  file400
├── [450K]  file450
└── [500K]  file500
C
├── [550K]  file550
└── [600K]  file600

0 directories, 13 files