jenkins conditional to check if push is allowed

jenkins-conditional-push-check.sh

# Rebase any commits on top of anything new from remote
git pull --rebase $UPSTREAM_GIT_REMOTE $UPSTREAM_GIT_BRANCH

# get the tracking-branch name
tracking_branch=$(git for-each-ref --format='%(upstream:short)' $(git symbolic-ref -q HEAD))

# creates global variables $1 and $2 based on left vs. right tracking
# inspired by @adam_spiers
set -- $(git rev-list --left-right --count $tracking_branch...HEAD)
behind=$1
ahead=$2

if [ $behind -gt 0 ] || [ $ahead -lt 1 ]; then
    exit 1
fi