This question is very general and there are a couple of assumptions I'll make to simplify it a bit. We'll assume that you want to update your master branch.
If you haven't made any changes locally, you can use git pull to bring down any new commits and add them to your master.
git pull origin master
If you have made changes, and you want to avoid adding a new merge commit, use git pull --rebase.
git pull --rebase origin master
git pull --rebase will work even if you haven't made changes and is probably your best call.
To pull from the default branch, new repositories should use the command:
git pull origin main
Github changed naming convention of default branch from master to main in 2020. https://github.com/github/renaming
This should work for every default repo:
git pull origin master
If your default branch is different than master, you will need to specify the branch name:
git pull origin my_default_branch_name
git fetch [remotename]
However you'll need to merge any changes into your local branches. If you're on a branch that's tracking a remote branch on Github, then
git pull
will first do a fetch, and then merge in the tracked branch
With an already-set origin master, you just have to use the below command -
git pull "https://github.com/yourUserName/yourRepo.git"
Source: Stackoverflow.com