Can I hold git credentials in environment variables?

I'd like to create a very simple shell script, which will ultimately be called by another application, that updates a local git repository:

#!/bin/bash

cd $1
sudo git pull

When executing this I'm asked for credentials (I'm pulling from a private BitBucket repository).

Can I ( briefly) store credentials in environment variables?

#!/bin/bash

export  GIT_USERNAME=<user>
export  GIT_PASSWORD=<pass>

cd $1
sudo git pull

The above doesn't work. Would anything? I could programmatically modify the origin url but that seems a bit execessive.

I know that it's very old question but if you really need to pass username and password for HTTP basic authentication you can just set helper like this:

git config credential.helper '!f() { sleep 1; echo "username=${GIT_USER}"; echo "password=${GIT_PASSWORD}"; }; f'

UPDATE: I've added sleep 1 to the function. In some environments it may be probably needed due to race condition. I've got 2 virtual machines running Debian Jessie. They had the same architecture but different CPU and different number of cores. On one of these machines the helper was working fine without sleep. On the other one it wasn't. After few hours of debugging I run strace to see what's happening. And it magically started to work. strace just made git a little bit slower.

You can set the username in the git config with:

git config credential.https://github.com.username $GIT_USER

Then you can set the GIT_ASKPASS environment variable to a script that will provide the password:

export GIT_ASKPASS=/path/to/git_env_password.sh

The contents of git_env_password.sh would be:

#!/bin/bash
echo $GIT_PASSWORD

N.B: This will store the username in the git config, so if you are not okay with that use another solution.

For more info consult the gitcredentials man page.