because why not

files/sponge

@@ -1,25 +1,69 @@
 #!/usr/bin/env python3
 
 import sys
+import time
 from argparse import ArgumentParser
 
-# Set up options
-parser=ArgumentParser(description="Sponge file before writing output: grep foo file.txt | sponge file.txt",
-                      epilog="This tool is a modification from http://joeyh.name/code/moreutils/ with the same name.")
-parser.add_argument("-a",action="store_true",dest="append",default=False,
-                  help="Append to file instead of overwriting")
-parser.add_argument(type=str,dest="file",
-                  help="File to write to")
-options=parser.parse_args()
 
-# Read data
-data=sys.stdin.read()
+class Verbose:
+    def __init__(self):
+        self.progress_chars = " ▏▎▍▌▋▊▉█"
+        self.progress_n = 0
+        self.ts = 0
+        self.loops = 0
+
+    def next(self):
+        if time.time() > self.ts + 0.1:
+            s = (
+                " "
+                + self.loops * self.progress_chars[-1]
+                + self.progress_chars[self.progress_n]
+                + "\r"
+            )
+            print(s, file=sys.stderr, end="")
+            self.progress_n = (1 + self.progress_n) % len(self.progress_chars)
+            if self.progress_n == 0:
+                self.loops += 1
+            if self.loops >= 10:
+                print(" " * 11 + "\r", file=sys.stderr, end="")
+                self.loops = 0
+            sys.stderr.flush()
+            self.ts = time.time()
+
+
+# Set up options
+parser = ArgumentParser(
+    description="Sponge file before writing output: grep foo file.txt | sponge file.txt",
+    epilog="This tool is a modification from http://joeyh.name/code/moreutils/ with the same name.",
+)
+parser.add_argument(
+    "-a",
+    action="store_true",
+    dest="append",
+    default=False,
+    help="Append to file instead of overwriting",
+)
+parser.add_argument(
+    "-v", action="store_true", dest="verbose", default=False, help="Progress to stderr"
+)
+parser.add_argument(type=str, dest="file", help="File to write to")
+options = parser.parse_args()
+
 
 # choose mode
-mode="w"
+mode = "wb"
 if options.append:
-    mode="a"
+    mode = "ab"
+if options.verbose:
+    v = Verbose()
+chunk_size = 1024 * 1024 * 1  # Mb
+
 # Write the file
-writer=open(options.file, mode)
-writer.write(data)
-writer.close()
+with open(options.file, mode) as writer:
+    while True:
+        chunk = sys.stdin.buffer.read(chunk_size)
+        if not chunk:
+            break
+        if options.verbose:
+            v.next()
+        writer.write(chunk)