TL;DR: copy latest Git commit hash:
git show --oneline | head -1 | awk '{ print $1 }' | pbcopy
git show
git show --oneline
Extract the first line with head:
head -1
Print the first field with awk:
awk '{ print $1 }'
Copy result to clipboard with pbcopy:
pbcopy
Putting it together with pipe:
git show --oneline | head -1 | awk '{ print $1 }' | pbcopy
git log
Copy the latest commit sha with git log:
git log --oneline | head -1 | awk '{ print $1 }' | pbcopy