Batch script to merge files without Hex char 1A at the end

I'm merging two ASCII files via a simple batch script like this

COPY a.txt+b.txt c.txt /y /a

The problem is, the very last character in C gets set to 1A, the HEX notation for SUB. c.txt is fed into another executable which does not like the 1A at the end.

After c.txt is generated, if I open it up in Notepad++ and remove the last character, the file works fine.

How could I merge the a.txt and b.txt without 1A getting appended to the end of c.txt ?

The placing of /a and /b switches is critical. They perform differently depending on whether they are placed after the source filename(s) or the target filename.

When used with a target filename, /a causes the end-of-file marker (ASCII 26) to be added. You are actually specifying this!

When used with the source filename,

/a specifies the file is ASCII and it's copied up to but not including the first ASCII 26 end-of-file mark. That character and anything after it is ignored.

/b causes the entire file to be copied, including any end-of-file markers and anything after them.

When used with the destination filename,

/a causes ASCII 26 to be added as the last character.

/b does not add ASCII 26 as the last character.

Your solution

...although I haven't tested it, is probably to use

COPY a.txt+b.txt /a c.txt /b /y