===== Tips and Tricks =====

==== Useful GIT-Tools and Commands ====

=== Useful Git-Tools ===

  * gitk

  * tig:
     Path on mistral: /sw/rhel6-x64/vcs/tig-2.2.1/bin/tig
     Path on workstations: /usr/bin/tig
     short blog entry: https://www.atlassian.com/blog/git/git-tig
     cheat sheet: http://ricostacruz.com/cheatsheets/tig.html
     manual: http://jonas.nitro.dk/tig/manual.html
     (Thanks to Ralf Mueller)

=== Useful Git Commands ===

  * Checkout a version with a special hash tag:
    git checkout 89aa38fc

You may have to "git submodule update" again.
Looking at the status the first line of the message will be
  HEAD detached at 89aa38f

This, of course, only works for hash tag inside your cloned repository, e.g. icon-aes.git.

  * Checkout a new branch and branch off from a special hash tag:
  git checkout -b my_new_branch 89aa38fc


  * Delete a (local) branch
  git branch -d my_new_branch


  * Cherrypicking a range of commits
  git cherry-pick 3020e317..9b9d68c8 origin/icon-aes-other-branch
  
==== Extend your prompt with the current branch ====

If the directory does not exist 
  mkdir -p $HOME/.config/git

change to
  cd $HOME/.config/git

and copy
  wget https://raw.githubusercontent.com/git/git/master/contrib/completion/git-prompt.sh

edit ''$HOME/.bashrc''; add
  if [[ -f $HOME/.config/git/git-prompt.sh ]]
  then
      source $HOME/.config/git/git-prompt.sh
      export -f __git_ps1
  fi
  export PS1='\[\e[32m\]\u@\h$(__git_ps1 "\[\e[36m\](%s)\[\e[0m\]")%\[\e[38m\] \[\e[0m\]'

gives a prompt of the following form inside of a git repository
  userid@hostname(git branch)%

and
  userid@hostname%

else.
(Hint: Try zsh with a good preconfigured .zshrc like ''wget -O .zshrc http://git.grml.org/f/grml-etc-core/etc/zsh/zshrc'' . Gives you tab completion for most git operations, remote (scp) autocompletion, and a lot more.)

*Copy of Notes on GIT

==== Add the current repository- and branch name to the commit message automatically ====

This needs to be applied by each developer. The tool of choice are the Git hooks. Hooks are scripts executed at a certain point of the Git workflow. They can be written in any language your shell supports. In this case we are interested in executing a script on the client side before we commit. We have in our repository’s .git/hooks folder a set of examples, which you should ignore!
Copy the following script
  #! /bin/bash
  
  # Just do nothing if there is a header already
  expr "`head -1 $1`" : '[[:space:]]*\(\[[^]]*\]\)' > /dev/null && exit
  
  # Prepend header with repo and branch name to current message
  branch_name=$(git symbolic-ref --short HEAD)
  branch_name="${branch_name##*/}" 
  repo_name=$(git config --get remote.origin.url | perl -pe 's/.*:(.*)\.git/$1/')
  repo_name="${repo_name##*/}"
  header=$(echo "$repo_name $branch_name" | awk '{ printf "[%s:%s]", $1, $2 }')
  echo "$header $(cat $1)" > $1

into the .git/hooks folder and call the file ''prepare-commit-msg''. Make it executable:
  chmod +x .git/hooks/prepare-commit-msg

Every commit will automatically add
  [your_origin repository name:your branch name] 

eg.
  [icon-cimd:icon-cimd-tcmalloc]

to the commit message.

In case you have several cloned repositories, you may move the script to a common directory to hold the hooks for all your repositories:
  mkdir -p $HOME/.config/git/hooks
  mv .git/hooks/prepare-commit-msg $HOME/.config/git/hooks
  git config --global core.hooksPath $HOME/.config/git/hooks

If you do //not// want a common hook directory, you will have to add the script to every ''.git/hooks'' directory. In this case it still helps to copy the file prepare-commit-msg to a central place and simply copy it to the different clones.

Note that with the common directory in ''core.hooksPath'', any remaining ''.git/hooks'' within your repositories will be ignored. If you need special hooks for some repository, you may add a fallback to ''.git/hooks'' by adding the following lines between the first and the second line of the common hook script:
  # Check for local hook
  hook_name=$(basename $0)
  local_hook_name=$PWD/.git/hooks/$hook_name
  [ -x $local_hook_name ] && exec $local_hook_name "$@"

*Copy of Cookbook

==== Seven rules of a great commit message ====

  - separate subject from body with a blank line,
  - limit the subject line to 50 characters,
  - capitalize the subject line,
  - do not end the subject line with a period,
  - use the imperative mood in the subject line,
  - wrap the body at 72 characters, and
  - use the body to explain what and why versus how.

*Copy of Notes on GIT

-----
 --- //[[monika.esch@mpimet.mpg.de|Monika Esch]] 2020/10/26 16:32//
 --- //[[karl-hermann.wieners@mpimet.mpg.de|Karl-Hermann Wieners]] 2022/04/20 13:00//