Node:Dry Runs, Previous:Inexact, Up:Imperfect

#### Predicting what `patch` will do

It may not be obvious in advance what `patch` will do with a complicated or poorly formatted patch. If you are concerned that the input might cause `patch` to modify the wrong files, you can use the `--dry-run` option, which causes `patch` to print the results of applying patches without actually changing any files. You can then inspect the diagnostics generated by the dry run to see whether `patch` will modify the files that you expect. If the patch does not do what you want, you can modify the patch (or the other options to `patch`) and try another dry run. Once you are satisfied with the proposed patch you can apply it by invoking `patch` as before, but this time without the `--dry-run` option.