Add pre-push hook example

Author: Nikita Korotkih

examples/pre-push/prevent-force-push-to-master

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+# Sometimes it's better to not allow users to make force pushes to some branches.
+# It can cause losing of some commits and can be pain for a team.
+# If you want to protect from doing such a harmful action then add protected branches to "protected_branches" variable.
+
+protected_branch='(master|dev)' # you can set up multiple protected branches
+
+policy='[Policy] Never force push or delete the '$protected_branch' branch! (Prevented with pre-push hook.)'
+
+parent_pid=$(ps -oppid= -p $PPID)
+push_command=$(ps -ocommand= -p $parent_pid)
+
+is_destructive='force|delete|\-f'
+will_remove_protected_branch=':'$protected_branch
+
+if ([[ $push_command =~ $is_destructive ]] && [[ $push_command =~ $protected_branch ]]) \
+    || [[ $push_command =~ $will_remove_protected_branch ]]
+then
+  echo $policy
+  exit 1
+fi