how to get git log without the commit message

Try this

git log --numstat --format=

You can do:

$ git log --stat --format="%H"

You can customize it as you needed. Here

$ git log --pretty=format:"%h $ad- %s [%an]"

Here:
- %ad = author date
- %an = author name
- %h = commit hash (short)
- %H = commit hash (full)
- %s = subject
- %d = ref names
 

Git's pretty docs lists all placeholders.