Post-update git hook to set right owner and permissions for changed files

post-merge

#!/bin/sh

# default owner user
OWNER="www-data:www-data"

# changed file permission
PERMISSION="664"

# web repository directory
REPO_DIR="/var/www/sitename"

# remote repository 
REMOTE_REPO="origin"

# public branch of the remote repository
REMOTE_REPO_BRANCH="master"

cd $REPO_DIR || exit
unset GIT_DIR
files="$(git diff-tree -r --name-only --no-commit-id HEAD@{1} HEAD)"
git merge FETCH_HEAD

for file in $files
do
  sudo chown $OWNER $file
  sudo chmod $PERMISSION $file
done

exec git-update-server-info

can you run me through what this is doing?

files="$(git diff-tree -r --name-only --no-commit-id HEAD@{1} HEAD)"

specifically the --no-commit-id HEAD@{1} HEAD

@fishtankmike

git diff-tree -r --name-only --no-commit-id HEAD@{1} HEAD

The format of the command above is

git diff-tree <commit_ID_start> <commit_ID_end>

First of all, let's take a look at diff-tree, what does it use for? Actually diff-tree shows the differences from <commit_ID_start> to <commit_ID_end> from reflog， in this case, HEAD@{1} is the <commit_ID_start> and HEAD is the <commit_ID_end>.

Now we can change the command as below

git diff-tree HEAD@{1} HEAD

Now, run git reflog, you should know what HEAD@{1} means, actually it stands for the last reflog, while HEAD@{0} stands for the current reflog(which is HEAD)

So, git diff-tree HEAD@{1} HEAD is use to show the difference from the last commit HEAD@{1} and the current HEAD@{0}(HEAD) from the reflog.

As to --name-only and --no-commit-id, they are the options of diff-tree, see the command and it's output below

 > git diff-tree HEAD@{1} HEAD
:000000 100644 0000000000000000000000000000000000000000 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 A	README.md
:000000 100644 0000000000000000000000000000000000000000 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 A	aaa.html
:100644 000000 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0000000000000000000000000000000000000000 D	test.txt

 > git diff-tree --name-only HEAD@{1} HEAD
README.md
aaa.html
test.txt

well, if --name-only can get the name, what does --no-commit-id use for? see the screenshot below(screenshot from git diff-tree --help)

As to -r, I think you already know, it refers to recursively.