readlink: support multiple command line arguments

This allows efficient processing of multiple files,
while also increasing compatibility with BSD's readlink(1).
We also add the -z, --zero option to delimit output items
with the NUL character which disambiguates output in the
presence of '\n' characters.

* src/readlink.c (usage): Add the --zero description,
and also adjust the description of --no-newline accordingly.
(main): Handle the -z option and iterate over multiple arguments.
Also as in commit v8.15-24-g9d46b25 we use fputs() and putchar()
rather than printf() for performance reasons.
* doc/coreutils.texi (readlink invocation): Document the
new --zero option, adjust the --no-newline description, and
tweak the general info to indicate multiple files are supported.
* tests/readlink/multi.sh: A new test for the new functionality.
* tests/local.mk: Reference the new test.
* man/readlink.x: Adjust the summary and also reference realpath.
* NEWS: Mention the improvement.
* THANKS.in: Suggested by Aaron Davies.

1 files changed, 1 insertions, 0 deletions

diff --git a/THANKS.in b/THANKS.in
index 900979517..c2651e7ee 100644
--- a/THANKS.in
+++ b/THANKS.in
@@ -14,6 +14,7 @@ note to the bug-report mailing list (as seen at end of e.g., cp --help).
 
 ???                                 kytek@cybercomm.net
 A Costa                             agcosta@gis.net
+Aaron Davies                        aaron.davies@gmail.com
 Aaron Hawley                        ashawley@uvm.edu
 Achim Blumensath                    blume@corona.oche.de
 Adam Jimerson                       vendion@charter.net