patch

• Given that changes.diff is created with from file1.txt to file2.txt
• Hunk is a modification

# Modify file1.txt with the changes
patch < changes.diff

# Revert a patch applied
patch -R < changes.diff

patch -Np1 <$t2_patch

Rejects

• If a file fails to be patched (conflicts), it is created a .rej (with the lines failed to patch) and a .orig with the original file before the partial changes
• Some hunks can still be patched successfully, in this case a file will be partially patched