Re: [PATCH] t9001: avoid not portable '\n' with sed

On Wed, Jun 04, 2014 at 10:42:46AM -0700, Junio C Hamano wrote:

Torsten Bögershausen [off-list ref] writes:

quoted

t9001 used a '\n' in a sed expression to split one line into two lines.
Some versions of sed simply ignore the '\' before the 'n', treating
'\n' as 'n'.

As the test already requires perl as a prerequisite, use perl instead of sed.

Signed-off-by: Torsten Bögershausen <redacted>
---

Hmph.  I read this in pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html

    The escape sequence '\n' shall match a <newline> embedded in the
    pattern space.

so it may be better to be a bit more explicit in the log message to
say whose implementation has this issue to warn people.

quoted

-	sed "s/^From:/$header: extra@address.com\nFrom:/" cover-to-edit.patch >"$cover" &&
+	"$PERL_PATH" -pe "s/^From:/$header: extra\@address.com\nFrom:/" cover-to-edit.patch | tr Q "$LF" >"$cover" &&

Note that quoted section of POSIX says "embedded in the pattern space";
under the description of the "s" command, it says:

	The replacement string shall be scanned from beginning to end.
	[...]
	The meaning of a <backslash> immediately followed by any
	character other than '&', <backslash>, a digit, or the delimiter
	character used for this command, is unspecified.

	A line can be split by substituting a <newline> into it. The
	application shall escape the <newline> in the replacement by
	preceding it by a <backslash>.

So the portable way to do it is:

	sed "s/^From:/$header: extra@address.com\
From:/" cover-to-edit.patch >"$cover" &&

but that requires the continuation to start in column 0, so the Perl
variant is probably neater.