lsns: add -H, --list-columns option

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

diff --git a/sys-utils/lsns.8.adoc b/sys-utils/lsns.8.adoc
index 016772711c5f86830b687a4ca9f606c1bb65b336..ec79cf0ed3c315211ee50f48cc4f403d4392280d 100644 (file)
--- a/sys-utils/lsns.8.adoc
+++ b/sys-utils/lsns.8.adoc
@@ -31,6 +31,9 @@ Note that *lsns* reads information directly from the _/proc_ filesystem and for
 
 == OPTIONS
 
+*-H*, *--list-columns*::
+List the available columns, use with *--json* or *--raw* to get output in machine-readable format.
+
 *-J*, *--json*::
 Use JSON output format.
 

diff --git a/sys-utils/lsns.c b/sys-utils/lsns.c
index 1cd0abb45811a447af84ad44f8c0eb2a21c2af4e..f444f5e1a51f65c0e45456cefc007d8ddac376f4 100644 (file)
--- a/sys-utils/lsns.c
+++ b/sys-utils/lsns.c
@@ -22,9 +22,9 @@
 #include <wchar.h>
 #include <libsmartcols.h>
 #include <libmount.h>
+# include <stdbool.h>
 
 #ifdef HAVE_LINUX_NET_NAMESPACE_H
-# include <stdbool.h>
 # include <sys/socket.h>
 # include <linux/netlink.h>
 # include <linux/rtnetlink.h>
@@ -50,6 +50,7 @@
 #include "namespace.h"
 #include "idcache.h"
 #include "fileutils.h"
+#include "column-list-table.h"
 
 #include "debug.h"
 
@@ -1392,7 +1393,6 @@ static struct libscols_filter *new_filter(const char *query)
 static void __attribute__((__noreturn__)) usage(void)
 {
        FILE *out = stdout;
-       size_t i;
 
        fputs(USAGE_HEADER, out);
 
@@ -1417,17 +1417,27 @@ static void __attribute__((__noreturn__)) usage(void)
        fputs(_(" -T, --tree[=<rel>]     use tree format (parent, owner, or process)\n"), out);
 
        fputs(USAGE_SEPARATOR, out);
+       fputs(_(" -H, --list-columns     list the available columns\n"), out);
        fprintf(out, USAGE_HELP_OPTIONS(24));
-
-       fputs(USAGE_COLUMNS, out);
-       for (i = 0; i < ARRAY_SIZE(infos); i++)
-               fprintf(out, " %11s  %s\n", infos[i].name, _(infos[i].help));
-
        fprintf(out, USAGE_MAN_TAIL("lsns(8)"));
 
        exit(EXIT_SUCCESS);
 }
 
+static void __attribute__((__noreturn__)) list_colunms(bool raw, bool json)
+{
+   struct libscols_table *col_tb = xcolumn_list_table_new("lsns-columns", stdout, raw, json);
+
+   for (size_t i = 0; i < ARRAY_SIZE(infos); i++)
+           xcolumn_list_table_append_line(col_tb, infos[i].name,
+                                         infos[i].json_type, NULL,
+                                         _(infos[i].help));
+
+   scols_print_table(col_tb);
+   scols_unref_table(col_tb);
+
+   exit(EXIT_SUCCESS);
+}
 
 int main(int argc, char *argv[])
 {
@@ -1454,6 +1464,7 @@ int main(int argc, char *argv[])
                { "raw",        no_argument,       NULL, 'r' },
                { "type",       required_argument, NULL, 't' },
                { "tree",       optional_argument, NULL, 'T' },
+               { "list-columns", no_argument,     NULL, 'H' },
                { NULL, 0, NULL, 0 }
        };
 
@@ -1479,7 +1490,7 @@ int main(int argc, char *argv[])
        INIT_LIST_HEAD(&netnsids_cache);
 
        while ((c = getopt_long(argc, argv,
-                               "JlPp:o:nruhVt:T::WQ:", long_opts, NULL)) != -1) {
+                               "JlPp:o:nruhVt:T::WQ:H", long_opts, NULL)) != -1) {
 
                err_exclusive_options(c, long_opts, excl, excl_st);
 
@@ -1542,6 +1553,8 @@ int main(int argc, char *argv[])
                case 'Q':
                        ls.filter = new_filter(optarg);
                        break;
+               case 'H':
+                       list_colunms(ls.raw, ls.json);
 
                case 'h':
                        usage();