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/groups.c b/src/groups.c
index 53332d56b..d30c9fb41 100644
--- a/src/groups.c
+++ b/src/groups.c
@@ -114,13 +114,13 @@ main (int argc, char **argv)
       if (rgid == NO_GID && errno)
         error (EXIT_FAILURE, errno, _("cannot get real GID"));
 
-      if (!print_group_list (NULL, ruid, rgid, egid, true))
+      if (!print_group_list (NULL, ruid, rgid, egid, true, ' '))
         ok = false;
       putchar ('\n');
     }
   else
     {
-      /* At least one argument.  Divulge the details of the specified users. */
+      /* At least one argument.  Divulge the details of the specified users.  */
       while (optind < argc)
         {
           struct passwd *pwd = getpwnam (argv[optind]);
@@ -130,7 +130,7 @@ main (int argc, char **argv)
           rgid = egid = pwd->pw_gid;
 
           printf ("%s : ", argv[optind]);
-          if (!print_group_list (argv[optind++], ruid, rgid, egid, true))
+          if (!print_group_list (argv[optind++], ruid, rgid, egid, true, ' '))
             ok = false;
           putchar ('\n');
         }