Special equal character with sed from shell

Question

My environment:

I am working with the command interpreter on Windows.

I use an sh.exe that came with some proprietary tools I have installed. I do not know the details of that sh.exe but here is what I get when querying its version:

>sh.exe --version
GNU bash, version 3.1.23(1)-release (i686-pc-msys)
Copyright (C) 2005 Free Software Foundation, Inc.

Similarly, here is what I have for sed:

>sed --version
GNU sed version 4.2.1
Copyright (C) 2009 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE,
to the extent permitted by law.

GNU sed home page: <http://www.gnu.org/software/sed/>.
General help using GNU software: <http://www.gnu.org/gethelp/>.
E-mail bug reports to: <[email protected]>.
Be sure to include the word ``sed'' somewhere in the ``Subject:'' field.

What I am after:

I would like to be able to use a sed command that matches for the equal character and do so from a shell script.

This works as expected:

>echo "a=b" | sed "s/a=//"
"b"

If parse_trace.sh contains

#!/bin/sh

sed "s/a//"

I also get what I expect:

>echo "a=b" | sh parse_trace.sh
"=b"

However, replacing the last line of my script with:

sed "s/a=//"

leads to

>echo "a=b" | sh parse_trace.sh
sed.exe: -e expression #1, char 5: unterminated `s' command

And if I use instead

sed "s/a\=//"

I get

>echo "a=b" | sh parse_trace.sh
"==b"

What am I missing?

Update

The = sign is correctly interpreted within my shell script if it isn't the last character in the pattern. I.e. if my last line in the script is now:

sed "s/a=b//"

Then I get:

echo "a=b" | sh parse_trace.sh
""

echo "a=bc" | sh parse_trace.sh
"c"

So there is something about the =/ that makes the DOS-SHELL combo fail somehow.

Update 2

>od -Ax -tx1z parse_trace.sh
000000 23 21 2f 62 69 6e 2f 73 68 0a 0a 73 65 64 20 22  >#!/bin/sh..sed "<
000010 73 2f 61 5c 3d 2f 2f 22 0a 0a                    >s/a\=//"..<
00001a

>echo "a=b" | sh -x parse_trace.sh
+ sed 's/a\=//'
"==b"

>od -Ax -tx1z parse_trace.sh
000000 23 21 2f 62 69 6e 2f 73 68 0a 0a 73 65 64 20 22  >#!/bin/sh..sed "<
000010 73 2f 61 3d 2f 2f 22 0a 0a                       >s/a=//"..<
000019

>echo "a=b" | sh -x parse_trace.sh
+ sed s/a=//
sed.exe: -e expression #1, char 5: unterminated `s' command

Answer 1

I'm not sure it will works, but I think it's a good shot:

sed 's,a\x3d,,'

I tried it in my environment, it works. There are two things might be the reason you got that situation:
a. The sh you are using and the cmd together treat '/' and '\' both delimiter of sed.
b. You are using double quotes, which bash will try to find equation and vars inside it.

I myself use cmd combined with shell commands a lot, I would recommend you try cygwin. Add cygin's bin path to PATH of windows, will works like a charm. But you need be careful about ESCAPE.