Playing with git diff

.gitattributes

otherfile diff=differ

.gitconfig

[diff "differ"]                                                                                                                                                                                                                               
    command = /home/mullins/devel/pokusy/differ.sh   

differ.sh

#!/usr/bin/env bash                                                                                                                                                                                                                           
                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                              
echo "                                                                                                                                                                                                                                        
path:     $1                                                                                                                                                                                                                                  
old_file: $2                                                                                                                                                                                                                                  
old_hash: $3                                                                                                                                                                                                                                  
old_perm: $4                                                                                                                                                                                                                                  
new_file: $5                                                                                                                                                                                                                                  
new_hash: $6                                                                                                                                                                                                                                  
new_perm: $7                                                                                                                                                                                                                                  
"                                                                                                                                                                                                                                             
                                                                                                                                                                                                                                              
echo "Old file"                                                                                                                                                                                                                               
cat $2                                                                                                                                                                                                                                        
                                                                                                                                                                                                                                              
echo "New file"                                                                                                                                                                                                                               
cat $5