There are times notifications aren't wanted about either a changed repo file or a new file that needs to be added to the repo. However, adding the name of the file to .gitignore might not be a good option, either. For example, locally-generated files that other users aren't likely to generate (e.g., files created by an editor) or files of experimental test code might not be appropriate to appear in a .gitignore file.

In those cases, use one of these solutions:

0. If the file is a changed repo file

   Use the command:

   git update-index --assume-unchanged "$FILE"

   To undo this, use the command:

   git update-index --no-assume-unchanged "$FILE"

   The update-index command doesn't work with new files that haven't been added to the repo yet, though.

1. If the file is new and not added to the repo

   Add its filename to the repo's exclude file:

   echo "$FILE" >> .git/info/exclude

   This also works for changed repo files, but there isn't a specific undo command for it. The exclude file would need to be edited and the filename deleted from it. Or other commands could approximate it:

   ex -s -c"g/^${FILE}\$/d" -cwq .git/info/exclude

   Note that this overwrites the existing exclude file and if the filename specified contains special characters that could affect the regular expression, the results are unpredictable.

   This usage of the exclude file is recommended by the page "Ignoring files" on GitHub Help.