Add jaraco.text.show-newlines command.

CHANGES.rst

@@ -1,3 +1,8 @@
+v3.9.0
+======
+
+Add ``jaraco.text.show-newlines`` script.
+
 v3.8.1
 ======
 

README.rst

@@ -42,6 +42,16 @@ layout to another::
     echo  "',.pyf" | python -m jaraco.text.to-qwerty
     qwerty
 
+Newline Reporting
+=================
+
+Need to know what newlines appear in a file?
+
+::
+
+    $ python -m jaraco.text.show-newlines README.rst
+    newline is '\n'
+
 For Enterprise
 ==============
 

jaraco/text/__init__.py

@@ -598,3 +598,22 @@ def join_continuation(lines):
             except StopIteration:
                 return
         yield item
+
+
+def read_newlines(filename, limit=1024):
+    r"""
+    >>> tmp_path = getfixture('tmp_path')
+    >>> filename = tmp_path / 'out.txt'
+    >>> _ = filename.write_text('foo\n')
+    >>> read_newlines(filename)
+    '\n'
+    >>> _ = filename.write_text('foo\r\n')
+    >>> read_newlines(filename)
+    '\r\n'
+    >>> _ = filename.write_text('foo\r\nbar\nbing\r')
+    >>> read_newlines(filename)
+    ('\r', '\n', '\r\n')
+    """
+    with open(filename) as fp:
+        fp.read(limit)
+    return fp.newlines

jaraco/text/show-newlines.py

@@ -0,0 +1,31 @@
+import autocommand
+import inflect
+
+from more_itertools import always_iterable
+
+import jaraco.text
+
+
+def report_newlines(filename):
+    r"""
+    Report the newlines in the indicated file.
+
+    >>> report_newlines(__file__)
+    newline is '\n'
+    >>> tmp_path = getfixture('tmp_path')
+    >>> filename = tmp_path / 'out.txt'
+    >>> _ = filename.write_text('foo\nbar\r\n')
+    >>> report_newlines(filename)
+    newlines are ('\n', '\r\n')
+    """
+    newlines = jaraco.text.read_newlines(filename)
+    count = len(tuple(always_iterable(newlines)))
+    engine = inflect.engine()
+    print(
+        engine.plural_noun("newline", count),
+        engine.plural_verb("is", count),
+        repr(newlines),
+    )
+
+
+autocommand.autocommand(__name__)(report_newlines)

setup.cfg

@@ -20,6 +20,9 @@ install_requires =
 	jaraco.functools
 	jaraco.context >= 4.1
 	importlib_resources; python_version < "3.9"
+	autocommand
+	inflect
+	more_itertools
 
 [options.packages.find]
 exclude =