join,sort,uniq: with -z, treat '\n' as a field separator

* NEWS: Mention the change in behavior.
* doc/coreutils.texi (newlineFieldSeparator): A new description,
referenced from ({join,sort,uniq} invocation).
* src/system.h (field_sep): A new inline function to determine
if a character is a field separator.
* src/join.c (usage): s/whitespace/blank/ to be more accurate
wrt which characters are field separators.
(xfields): s/isblank/field_sep/.
* src/sort.c (inittables): Likewise.
* src/uniq.c (find_field): Likewise.
* tests/misc/join.pl: Adjust -z test, and add a test/example
for processing the whole record with field processing.
* tests/misc/sort.pl: Add -z test cases, including case with '\n'.
* tests/misc/uniq.pl: Add -z -f test case with \n.

1 files changed, 6 insertions, 3 deletions

diff --git a/tests/misc/join.pl b/tests/misc/join.pl
index 2a40f0095..4d399d8ae 100755
--- a/tests/misc/join.pl
+++ b/tests/misc/join.pl
@@ -290,10 +290,13 @@ my @tv = (
 # missing last NUL at the end of the last line (=end of file)
 ['z4', '-z',
  ["a\0c\0e", "a\0b\0c"], "a\0c\0", 0],
-# edge-case: the embedded newlines should treated as
-# part of the nul-terminated line
+# With -z, embedded newlines are treated as field separators.
+# Note '\n' are converted to ' ' in this case.
 ['z5', '-z -a1 -a2',
- ["a\n1\0c 3\0","b\n8\0c 9\0"], "a\n1\0b\n8\0c 3 9\0"],
+ ["a\n\n1\0c 3\0", "a 2\0b\n8\0c 9\0"], "a 1 2\0b 8\0c 3 9\0"],
+# One can avoid field processing like:
+['z6', '-z -t ""',
+ ["a\n1\n\0", "a\n1\n\0"], "a\n1\n\0"],
 
 );