Where is git config file?

Short answer:

1. .git/config in your active git repository;
2. ~/.gitconfig or ~/.config/git;
3. /etc/gitconfig

More detailed answer can be found in the git man page:

FILES
If not set explicitly with –file, there are four files where git config will search for configuration options:

$(prefix)/etc/gitconfig
System-wide configuration file.

$XDG_CONFIG_HOME/git/config
Second user-specific configuration file. If $XDG_CONFIG_HOME is not set or empty, $HOME/.config/git/config will be used. Any single-valued variable set in this file will be overwritten by whatever is in ~/.gitconfig. It is a good idea not to create this file if you sometimes use older versions of Git, as support for this file was added fairly recently.

~/.gitconfig
User-specific configuration file. Also called “global” configuration file.

$GIT_DIR/config
Repository specific configuration file.

If no further options are given, all reading options will read all of these files that are available. If the global or the system-wide configuration file are not available they will be ignored. If the repository configuration file is not available or readable, git config will exit with a non-zero error code. However, in neither case will an error message be issued.

The files are read in the order given above, with last value found taking precedence over values read earlier. When multiple values are taken then all values of a key from all files will be used.

All writing options will per default write to the repository specific configuration file. Note that this also affects options like –replace-all and –unset. git config will only ever change one file at a time.

You can override these rules either by command-line options or by environment variables. The –global and the –system options will limit the file used to the global or system-wide file respectively. The GIT_CONFIG environment variable has a similar effect, but you can specify any filename you want.