What does 10064 mean in Git?

When you do git commit command, you probably have seen this information

1
2

 delete mode 100644 layouts/resource/index.html
 create mode 100644 layouts/resource/section.html

but what does this series of number mean?

The values shown are the 16-bit file modes as stored by Git, you can check here to know more:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

  32-bit mode, split into (high to low bits)

    4-bit object type
      valid values in binary are 1000 (regular file), 1010 (symbolic link) and 1110 (gitlink)
    
    3-bit unused

    9-bit unix permission. Only 0755 and 0644 are valid for regular files.
    
    Symbolic links and gitlinks have value 0 in this field.

If the file doesn’t mention directories; they are represented using object type 0100.

Each digit in the six-digit value is in octal, representing three bits; 16 bits thus need six digits, the first of which only represents one bit:

1
2
3
4
5
6
7

Type|---|Perm bits

1000 000 111101101
1 0   0   7  5  5

1000 000 110100100
1 0   0   6  4  4

Git doesn’t store arbitrary modes, only a subset of the values are allowed, from the usual POSIX types and modes (in octal, 12 for a symbolic link, 10 for a regular file, 04 for a directory) to which git adds 16 for Git links. The mode is appended, using four octal digits.

For files,

you’ll only ever see 100755 or 100644 (although 100664 is also technically possible);

directories are 040000 (permissions are ignored),

symbolic links 120000.

The set-user-ID, set-group-ID and sticky bits aren’t supported at all (they would be stored in the unused bits).