-* `overwrite` Is the default and overwrites the original files _without_ creating backups.
-* `replace` Overwrites the original files after creating backups of the files.
-* `display` Will print the formatted files to stdout.
-* `plain` Also writes to stdout, but with no metadata.
-* `diff` Will print a diff between the original files and formatted files to stdout.
- Will also exit with an error code if there are any differences.
-* `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
- that can be used by tools like Jenkins.
-
-The write mode can be set by passing the `--write-mode` flag on
-the command line. For example `rustfmt --write-mode=display src/filename.rs`
-
-`cargo fmt` uses `--write-mode=overwrite` by default.
-
-If you want to restrict reformatting to specific sets of lines, you can
-use the `--file-lines` option. Its argument is a JSON array of objects
-with `file` and `range` properties, where `file` is a file name, and
-`range` is an array representing a range of lines like `[7,13]`. Ranges
-are 1-based and inclusive of both end points. Specifying an empty array
-will result in no files being formatted. For example,
-
-```
-rustfmt --file-lines '[
- {"file":"src/lib.rs","range":[7,13]},
- {"file":"src/lib.rs","range":[21,29]},
- {"file":"src/foo.rs","range":[10,11]},
- {"file":"src/foo.rs","range":[15,15]}]'
-```
+When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not
+make any formatting changes to the input, and `1` if Rustfmt would make changes.
+In other modes, Rustfmt will exit with `1` if there was some error during
+formatting (for example a parsing or internal error) and `0` if formatting
+completed without error (whether or not changes were made).