Automatically apply "git update-index --chmod=+x" to executable files

I frequently add bash scripts to my Git repository, and the scripts have executable permissions in the Linux filesystem prior to the git add. But after pushing the added files to a remote repository and pulling in another location, the files show up with non-executable permissions. There seem to be two ways to correct the problem:

1. chmod u+x $script 
   git commit -am "fixing the script permissions... again..."
   

2. git update-index --chmod=+x $script
   

Instead of fixing up the permissions every time, is there a way to have Git simply look at the file permissions on the script during git add, recognize "Hey, this here is an executable file!" and add it to the repository with the executable permissions directly?

git 2.9.X/2.10 (Q3 2016) brings chmod to git add itself!

See commit 4e55ed3 (31 May 2016) by Edward Thomson (ethomson).
Helped-by: Johannes Schindelin (dscho).
^{(Merged by Junio C Hamano -- gitster -- in commit c8b080a, 06 Jul 2016)}

add: add --chmod=+x / --chmod=-x options

The executable bit will not be detected (and therefore will not be set) for paths in a repository with core.filemode set to false, though the users may still wish to add files as executable for compatibility with other users who do have core.filemode functionality.
For example, Windows users adding shell scripts may wish to add them as executable for compatibility with users on non-Windows.

Although this can be done with a plumbing command (git update-index --add --chmod=+x foo), teaching the git-add command allows users to set a file executable with a command that they're already familiar with.

You can see the origin of this new feature in "How to create file execute mode permissions in Git on Windows?" (Feb. 2011)

There are several ways to do that.

1. Git aliases
2. Bash aliases
3. Or even combine bash and git aliases

1. Git aliases

   You can always use bash within your git alias.

   • Open your git config:

     vim ~/.gitconfig

   • Add an aliases section to it (if one does not exist):

     [alias]
         addscr = !sh -c 'if [[ ${0: -3} == ".sh" ]]; then git update-index --chmod=+x $0; git add $0'
     

2. Bash aliases

   • Edit your bash profile file:

     vim ~/.bashrc

   • Add this at the end of the file:

     function gitadd(){
         if [[ ${1: -3} == ".sh" ]]
             then git update-index --chmod=+x $1
         fi
         git add $1
      }
      alias gitadd='gitadd'
     

3. Combine git and bash aliases

   • Edit your bash profile file:

     vim ~/.bashrc

   • Add this to the end of the file:

     function checkShellFile(){
         return ${1: -3} == ".sh"
     }
     alias gitadd='checkShellFile ? git addsrcipt "$1" : && git add "$1"'
     

   • Edit your git config file:

     vim ~/.gitconfig

   • Add an aliases section to it (if one does not exist):

     [alias]
         addscript = !sh -c 'git update-index --chmod=+x $0 && git add $0'
     

None of the above has been tested

Here is a script to automatically apply git update-index --chmod+x to executable files:

for f in `find . -name '*.sh' -o -regex './s?bin/[^/]+' -o -regex './usr/sbin/[^/]+' -o -regex './usr/lib/[^/]+' `;do
 ( cd `dirname $f` && git update-index --chmod=+x  `basename $f` )
done