Git: Set up a fetch-only remote?

Apart from changing the push URL to something invalid (e.g., git remote set-url --push origin DISABLED), one can also use the pre-push hook.

One quick way to stop git push is to symlink /usr/bin/false to be the hook:

$ ln -s /usr/bin/false .git/hooks/pre-push
$ git push
error: failed to push some refs to '...'

Using a hook allows for more fine-grained control of pushes if desirable. See .git/hooks/pre-push.sample for an example of how to prevent pushing work-in-progress commits.

To prevent pushing to a specific branch or to limit pushing to a single branch, this in an example hook:

$ cat .git/hooks/pre-push
#!/usr/bin/sh

# An example hook script to limit pushing to a single remote.
#
# This hook is called with the following parameters:
#
# $1 -- Name of the remote to which the push is being done
# $2 -- URL to which the push is being done
#
# If this script exits with a non-zero status nothing will be pushed.

remote="$1"
url="$2"

[[ "$remote" == "origin" ]]

A test repo with multiple remotes:

$ git remote -v
origin  ../gitorigin (fetch)
origin  ../gitorigin (push)
upstream        ../gitupstream (fetch)
upstream        ../gitupstream (push)

Pushing to origin is allowed:

$ git push origin
Enumerating objects: 3, done.
Counting objects: 100% (3/3), done.
Writing objects: 100% (3/3), 222 bytes | 222.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To ../gitorigin
 * [new branch]      master -> master

Pushing to any other remote is not allowed:

$ git push upstream
error: failed to push some refs to '../gitupstream'

Note that the pre-push hook script can be modified to, among other things, print a message to stderr saying the push has been disabled.

I don't think you can remove the push URL, you can only override it to be something other than the pull URL. So I think the closest you'll get is something like this:

$ git remote set-url --push origin no-pushing
$ git push
fatal: 'no-pushing' does not appear to be a git repository
fatal: The remote end hung up unexpectedly

You are setting the push URL to no-pushing, which, as long as you don't have a folder of the same name in your working directory, git will not be able to locate. You are essentially forcing git to use a location that does not exist.