On Wed, Aug 25, 2021, at 12:06 PM, Sébastien Hinderer wrote: > Zack Weinberg (2021/08/25 11:39 -0400): > > m4_syscmd is a primitive, and it doesn't expand its argument, so you need > > to expand PKG_VERSION first: > > > > m4_syscmd([cat > VERSION << \END_OF_VERSION_FILE > > ]PKG_VERSION[ > > > > # Some comments about the format of version numbers > > END_OF_VERSION_FILE > > ]) > I double-checked my code and there was no \ before END_OF_VERSION_FILE > and the code was working so may I ask why you added one in your code?
That's an extra defensive measure. It makes the *shell* treat the here document as quoted, so that if your PKG_VERSION or your commentary ever happens to contain shell metacharacters they won't do anything surprising. I habitually add this to here documents unless there's a reason to *want* shell variable expansion (for instance) in some particular here document. zw
