add-user-to-repo.sh

#!/bin/bash

user=$1
repo=$2
permissions=$3

echo "Adding ${user} to repo ${repo} with permissions ${permissions}..."
gh api -XPUT repos/${repo}/collaborators/${user} -f permission=${permissions}
echo "done."

add-user-to-repos.sh

#!/bin/bash

user=$1
repos_file=$2
permissions=$3

for i in `cat ${repos_file}`
do
    ./add-user-to-repo.sh ${user} ${i} ${permissions}
done

Adding a user to a Github repository with specific permissions.
Also adding a user to a list of Github repositories in a file with specific permissions.