Git push to various repositories via bash script - bash

Question

I'm trying to create a bash script that iterates over 4 different folders (git repositories) and updates/pushes the changes for each one of them. I have the script mostly complete, except the authentication part.
Here's my current script:
#!/bin/bash
# Fetch username and password
echo "Please insert your git credentials!"
read -p 'Username: ' username
read -sp 'Password: ' password
# Check if you svn and git installed in your machine
if which svn &> /dev/null && which git &> /dev/null; then
# Store the current dir
CUR_DIR=$(pwd)
# Let the person running the script know what's going on.
echo "Pulling in latest changes for all repositories..."
for D in $CUR_DIR/*; do
if [ -d "${D}" ]; then
echo "${D}"
cd $(basename $D);
# Make sure SVN is on trunk branch and git branch is on master
SVN_BRANCH=$(svn info | grep '^URL:' | egrep -o '(tags|branches)/[^/]+|trunk' | egrep -o '[^/]+$')
GIT_BRANCH=$(git symbolic-ref --short HEAD)
if [ "$SVN_BRANCH"!="trunk" ] || [ "$GIT_BRANCH"!="master" ]; then
echo $CUR_DIR
echo "Make sure you're on SVN trunk branch and git master branch."
exit -1
fi
echo "Update SVN repository";
svn up
# Update git
git add .;
git commit -m "Update with the changes from svn trunk branch."
echo "Start pushing changes to main repository."
git push origin master
echo "Update git repository";
git pull origin master
# Update SVN
svn add .
svn commit -m "Update with changes from git master branch."
cd ..
fi
echo "Complete!"
done
else
echo "You need both svn and git CLI's installed to run this script!";
fi
As you can see, I'm already fetching the credentials in the beginning of the script, my problem is how can I use them to do the actions that need authentication, namely
git push origin master
git pull origin master
How can I build the git commands to make the authenticated request?