What is the meaning of ^M in git diff

git line-endings
Dennis Subachev picture Dennis Subachev · Jul 27, 2016 · Viewed 16.9k times · Source

I am diffing a file between forked and upstream BitBucket repos:

$ git diff origin/branchA..upstream/branchB -- some/file/path.xyz

It seems to return the same difference for almost every file:

-<U+FEFF>@using Sitecore.Mvc
+@using Sitecore.Mvc^M

What is the exact meaning of ^M that only shows up after the first line? I see this issue when I compare other files as well. I am on a Windows Server 2008 R2 machine. core.autocrlf is set to true. The .gitattributes is set to text eol=lf. My git version is 2.5.1.windows.1.

Answer

melpomene picture melpomene · Nov 18, 2018

^M represents carriage return. This diff means something removed a Unicode BOM from the beginning of the line and added a CR at the end.

The ^ symbol stands for Control, so ^M means Ctrl+M.

To get from that to the actual ASCII character code, you take the base character and flip bit 6 (i.e. XOR with 64). For letters, that just means subtract 64. So e.g. ^A is character code 1 (because A is 65). ^M is 77 - 64 = 13 (because M is 77), which corresponds to carriage return in ASCII.

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