Git filter to ignore lines in your files

git-ignore-line.sh

#!/bin/sh
# Git filter to ignore lines in your files.
#
# Copyright (c) 2017-2019 Aryel Mota Góis <aryel.gois@gmail.com>
#
# MIT License
#
#
# SETUP:
#
#     cp git-ignore-line.sh ~/bin/git-ignore-line
#
#
# USAGE:
#
# Mark single lines you want to ignore with 'GITIGNORE'. It ignores
# the whole line. It is recommended to be inside a comment in your code.
#
# Mark multiple lines surrounding them with 'GITIGNORE START' and
# 'GITIGNORE END'. It can not be nested.
#
# NOTE: Ignored lines might be lost on checkout.
#
#
# Add files to ignore:
#
#     git ignore-line <pattern>
#
# Remove patterns with:
#
#     git ignore-line -r <pattern>
#
# List configured patterns:
#
#     git ignore-line -l
#
# PATTERN can be a file or a glob pattern: '*.html'. Remember to
# escape the `*`.
#
#
# TODO:
#
# - Stash the lines ignored by this filter before a git checkout.


set -eu


# Check if stdin is not tty and remove ignored lines from it.

[ -t 0 ] || exec sed \
    '/GITIGNORE START/,/GITIGNORE END/d; /GITIGNORE/d' \
    /dev/stdin


# Running from tty.

program=$(basename "$0")

# Find git repository.
git_dir=$(git rev-parse --git-dir)

# Path to attributes file.
attr_file=$git_dir/info/attributes

# Check arguments.
if [ $# -eq 2 ] && [ "$1" = '-r' ]; then
    # Remove filter for pattern.
    sed "s|^$2 filter=$program||" "$attr_file" > "$attr_file.tmp"
    mv -- "$attr_file.tmp" "$attr_file"
elif [ $# -eq 1 ]; then
    if [ "$1" = '-l' ]; then
        # List patterns.
        grep "filter=$program" "$attr_file" || true
    else
        # Add filter for pattern.
        echo "$1 filter=$program" >> "$attr_file"
        # Configure filter.
        git config --global "filter.$program.clean" "$program"
        git config --global "filter.$program.smudge" cat
    fi
else
    # Show help.
    >&2 echo "Usage: $program [-r] <pattern>"
    >&2 echo "  or:  $program -l"
    exit 1
fi