Git command to display HEAD commit id?

Use the command:

git rev-parse HEAD

For the short version:

git rev-parse --short HEAD

git log -1

for only commit id

git log | head -n 1 

Old thread, still for future reference...:) even following works

git show-ref --head

by default HEAD is filtered out. Be careful about following though ; plural "heads" with a 's' at the end. The following command shows branches under "refs/heads"

 git show-ref --heads