Can git-bash and cygwin shell do the same things?

Question

On Windows 10, can git-bash and cygwin shell do the same things?

What can one do but the other can't?

For example,

1. As shells, can they both work the same as bash?

2. What programs and commands can run in one but not in the other?

   For example, in git-bash, I can't run some Windows command:

   $  reg add "HKCU\Software\Microsoft\VisualStudio\14.0_Config\MSBuild" /v EnableOutOfProcBuild /t REG_DWORD /d 0 /f
   ERROR: Invalid syntax.
   Type "REG ADD /?" for usage.
   

   But in Cygwin, it runs well

   $  reg add "HKCU\Software\Microsoft\VisualStudio\14.0_Config\MSBuild" /v EnableOutOfProcBuild /t REG_DWORD /d 0 /f
   The operation completed successfully.
   

   originally I thought that git-bash and cygwin can both run programs in Windows. So Why doesn't git-bash work, while cygwin can?

Thanks.

Answer 1

The difference is that Cygwin knows how to process so-called "Win32" pathnames. Loosely speaking, it knows that "\" is a pathname separator and not a shell escape character like it is in Bash. The error you showed is Bash interpreting "\" as an escape character. (Edit: you might try replacing one \ with two, thus escaping the backslash, so that Bash passes the command through to reg.exe correctly.)

Having said that, while Cygwin groks Windows pathnames, it doesn't like to do so. The documentation warns you off from using them. Of course, a little back-sliding now and then doesn't hurt. But while you can run Windows programs in Cygwin, hygiene suggests you should run Windows programs in the CMD.EXE processor and UNIX ones in Cygwin for your long-term sanity.

Answer 2

There is a lot of overlap between the two. But ultimately they are different implementations of bash/shall in Windows.

Cygwin has a large body of optional software you can install, including multiple different programming languages, compilers, various network tools, and so on. You can also install X and many X applications.

With git bash, you get what you get, and it's a bit more difficult to install additional tools. I actually have both on my workstation, because there's things I can't do in git bash. I've had very mixed success calling cygwin apps from the git bash window, too.

Also, cygwin is a full posix environment, not just a bash interpreter, so you can often compile non-distributed code within it, so for example if you found the source of a nice Linux tool you found, you can usually compile that tool for Cygwin. Not so much for git bash. And as I alluded above, even if you do compile it for Cygwin it likely won't work in git bash.

Other than that they are mostly very similar. It's kind of funny to see that git bash includes the cygpath command for converting Windows and Posix file paths, because git bash afaik is based on MinGW, which is a distinct solution from Cygwin.

Answer 3

I just found a difference: I can run this script in Git bash but not in Cygwin.

for file in *.xml; do
    echo "Processing file: $file"
    sed -r 's:<Autorizado>([0-9]+)</Autorizado>:<Autorizado>00013069</Autorizado>:' -i "$file"
    # ...
done

In Git bash, it process my xml files, but in Cygwin, it gives me error:

Processing file: *.xml
sed: cannot read *.xml: No such file or directory

bash --version in Git bash:

GNU bash, version 4.3.42(5)-release (x86_64-pc-msys)

in Cygwin:

GNU bash, versión 4.3.46(7)-release (x86_64-unknown-cygwin)