id: add -z, --zero option

* src/group-list.h (print_group_list): Add a parameter for the
delimiter of type char.
* src/group-list.c (print_group_list): Likewise, and use it instead
of a white space character to delimit the group entries.
* src/groups.c (main): Pass white space character to print_group_list().
* src/id.c (longopts):  Add array element for the new long option.
(usage): Document the new option.  While at it, fix the alignment
of the descriptions to match that of HELP_OPTION_DESCRIPTION.
(main): Define the bool flag opt_zero indicating the use of the
new option.  In the getopt_long loop, handle it.
Output an error diagnostic in the case the --zero option has been
specified together with the default format.
In the case of -gG, pass either a NUL or a white space character to
print_group_list() - depending on the above new flag.
Likewise change the printing of the final newline character: output
a NUL instead if the --zero option has been specified.
* doc/coreutils.texi (id invocation): Document the new option.
While at it, move the @exitstatus macro down after the macro
@primaryAndSupplementaryGroups in order to be consistent with
other texinfo documents.
(groups invocation): Move @exitstatus down after the macro
@primaryAndSupplementaryGroups here, too.
* tests/misc/id-zero.sh: Add new test exercising the new option.
* tests/local.mk (all_tests): Reference it.
* NEWS (New features): Mention the new option.
Fixes http://bugs.gnu.org/9987

1 files changed, 3 insertions, 3 deletions

diff --git a/src/group-list.c b/src/group-list.c
index 7d4995b5c..d54b05776 100644
--- a/src/group-list.c
+++ b/src/group-list.c
@@ -35,7 +35,7 @@
 extern bool
 print_group_list (const char *username,
                   uid_t ruid, gid_t rgid, gid_t egid,
-                  bool use_names)
+                  bool use_names, char delim)
 {
   bool ok = true;
   struct passwd *pwd = NULL;
@@ -52,7 +52,7 @@ print_group_list (const char *username,
 
   if (egid != rgid)
     {
-      putchar (' ');
+      putchar (delim);
       if (!print_group (egid, use_names))
         ok = false;
     }
@@ -79,7 +79,7 @@ print_group_list (const char *username,
     for (i = 0; i < n_groups; i++)
       if (groups[i] != rgid && groups[i] != egid)
         {
-          putchar (' ');
+          putchar (delim);
           if (!print_group (groups[i], use_names))
             ok = false;
         }