merge: cli pager

6 files changed, 288 insertions, 100 deletions

diff --git a/clients/cli/connections.c b/clients/cli/connections.c
index fc738d5cb5..5224ab784f 100644
--- a/clients/cli/connections.c
+++ b/clients/cli/connections.c
@@ -796,8 +796,33 @@ nmc_active_connection_state_to_color (NMActiveConnectionState state, NMMetaTermC
 		*color = NM_META_TERM_COLOR_RED;
 }
 
+/* Essentially a version of nm_setting_connection_get_connection_type() that
+ * prefers an alias instead of the settings name when in pretty print mode.
+ * That is so that we print "wifi" instead of "802-11-wireless" in "nmcli c". */
+static const char *
+connection_type_pretty (const char *type, NMCPrintOutput print_output)
+{
+	const NMMetaSettingInfoEditor *editor;
+	int i;
+
+	if (print_output == NMC_PRINT_TERSE)
+		return type;
+
+	for (i = 0; i < _NM_META_SETTING_TYPE_NUM; i++) {
+		editor = &nm_meta_setting_infos_editor[i];
+		if (strcmp (type, editor->general->setting_name) == 0) {
+			if (editor->alias)
+				return editor->alias;
+			break;
+		}
+	}
+
+	return type;
+}
+
 static void
-fill_output_connection (NMConnection *connection, NMClient *client, GPtrArray *output_data, gboolean active_only)
+fill_output_connection (NMConnection *connection, NMClient *client, NMCPrintOutput print_output,
+                        GPtrArray *output_data, gboolean active_only)
 {
 	NMSettingConnection *s_con;
 	guint64 timestamp;
@@ -845,7 +870,7 @@ fill_output_connection (NMConnection *connection, NMClient *client, GPtrArray *o
 
 	set_val_strc (arr, 0, nm_setting_connection_get_id (s_con));
 	set_val_strc (arr, 1, nm_setting_connection_get_uuid (s_con));
-	set_val_strc (arr, 2, nm_setting_connection_get_connection_type (s_con));
+	set_val_strc (arr, 2, connection_type_pretty (nm_setting_connection_get_connection_type (s_con), print_output));
 	set_val_str  (arr, 3, timestamp_str);
 	set_val_str  (arr, 4, timestamp ? timestamp_real_str : g_strdup (_("never")));
 	set_val_strc (arr, 5, nm_setting_connection_get_autoconnect (s_con) ? _("yes") : _("no"));
@@ -862,7 +887,7 @@ fill_output_connection (NMConnection *connection, NMClient *client, GPtrArray *o
 }
 
 static void
-fill_output_connection_for_invisible (NMActiveConnection *ac, GPtrArray *output_data)
+fill_output_connection_for_invisible (NMActiveConnection *ac, NMCPrintOutput print_output, GPtrArray *output_data)
 {
 	NmcOutputField *arr;
 	const char *ac_path = NULL;
@@ -878,7 +903,7 @@ fill_output_connection_for_invisible (NMActiveConnection *ac, GPtrArray *output_
 
 	set_val_str  (arr, 0, name);
 	set_val_strc (arr, 1, nm_active_connection_get_uuid (ac));
-	set_val_strc (arr, 2, nm_active_connection_get_connection_type (ac));
+	set_val_strc (arr, 2, connection_type_pretty (nm_active_connection_get_connection_type (ac), print_output));
 	set_val_strc (arr, 3, NULL);
 	set_val_strc (arr, 4, NULL);
 	set_val_strc (arr, 5, NULL);
@@ -1696,14 +1721,14 @@ do_connections_show (NmCli *nmc, int argc, char **argv)
 		 * (e.g. private connections of a different user). Show them as well. */
 		invisibles = get_invisible_active_connections (nmc);
 		for (i = 0; i < invisibles->len; i++)
-			fill_output_connection_for_invisible (invisibles->pdata[i], out.output_data);
+			fill_output_connection_for_invisible (invisibles->pdata[i], nmc->nmc_config.print_output, out.output_data);
 		g_ptr_array_free (invisibles, TRUE);
 
 		/* Sort the connections and fill the output data */
 		connections = nm_client_get_connections (nmc->client);
 		sorted_cons = sort_connections (connections, nmc, order);
 		for (i = 0; i < sorted_cons->len; i++)
-			fill_output_connection (sorted_cons->pdata[i], nmc->client, out.output_data, active_only);
+			fill_output_connection (sorted_cons->pdata[i], nmc->client, nmc->nmc_config.print_output, out.output_data, active_only);
 		g_ptr_array_free (sorted_cons, TRUE);
 
 		print_data_prepare_width (out.output_data);
diff --git a/clients/cli/general.c b/clients/cli/general.c
index 84c853aef0..7fa982fd2d 100644
--- a/clients/cli/general.c
+++ b/clients/cli/general.c
@@ -14,7 +14,7 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * Copyright 2010 - 2015 Red Hat, Inc.
+ * Copyright 2010 - 2017 Red Hat, Inc.
  */
 
 #include "nm-default.h"
@@ -1296,6 +1296,9 @@ do_overview (NmCli *nmc, int argc, char **argv)
 	/* Register polkit agent */
 	nmc_start_polkit_agent_start_try (nmc);
 
+	/* Optionally start paging the output. */
+	nmc_terminal_spawn_pager (&nmc->nmc_config);
+
 	/* The VPN connections don't have devices (yet?). */
 	p = nm_client_get_active_connections (nmc->client);
 	for (i = 0; i < p->len; i++) {
diff --git a/clients/cli/nmcli.c b/clients/cli/nmcli.c
index c712fdec21..70d78db6f0 100644
--- a/clients/cli/nmcli.c
+++ b/clients/cli/nmcli.c
@@ -16,7 +16,7 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * Copyright 2010 - 2015 Red Hat, Inc.
+ * Copyright 2010 - 2017 Red Hat, Inc.
  */
 
 #include "nm-default.h"
@@ -93,7 +93,9 @@ complete_field (GHashTable *h, const NmcMetaGenericInfo *const*field)
 static void
 complete_one (gpointer key, gpointer value, gpointer user_data)
 {
-	const char *prefix = user_data;
+	const char **option_with_value = user_data;
+	const char *option = option_with_value[0];
+	const char *prefix = option_with_value[1];
 	const char *name = key;
 	const char *last;
 
@@ -104,16 +106,23 @@ complete_one (gpointer key, gpointer value, gpointer user_data)
 		last = prefix;
 
 	if ((!*last && !strchr (name, '.')) || matches (last, name)) {
+		if (option != prefix) {
+			/* value prefix was not a standalone argument,
+			 * it was part of --option=<value> argument.
+			 * Repeat the part leading to "=". */
+			g_print ("%s=", option);
+		}
 		g_print ("%.*s%s%s\n", (int)(last-prefix), prefix, name,
 		                       strcmp (last, name) == 0 ? "," : "");
 	}
 }
 
 static void
-complete_fields (const char *prefix)
+complete_fields (const char *option, const char *prefix)
 {
 	guint i;
 	GHashTable *h;
+	const char *option_with_value[2] = { option, prefix };
 
 	h = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
 
@@ -144,10 +153,30 @@ complete_fields (const char *prefix)
 	for (i = 0; i < _NM_META_SETTING_TYPE_NUM; i++)
 		complete_field_setting (h, i);
 
-	g_hash_table_foreach (h, complete_one, (gpointer) prefix);
+	g_hash_table_foreach (h, complete_one, (gpointer) &option_with_value[0]);
 	g_hash_table_destroy (h);
 }
 
+static void
+complete_option_with_value (const char *option, const char *prefix, ...)
+{
+	va_list args;
+	const char *candidate;
+
+	va_start (args, prefix);
+	while ((candidate = va_arg (args, const char *))) {
+		if (!*prefix || matches (prefix, candidate)) {
+			if (option != prefix) {
+				/* value prefix was not a standalone argument,
+				 * it was part of --option=<value> argument.
+				 * Repeat the part leading to "=". */
+				g_print ("%s=", option);
+			}
+			g_print ("%s\n", candidate);
+		}
+	}
+	va_end (args);
+}
 
 static void
 usage (void)
@@ -191,6 +220,57 @@ static const NMCCommand nmcli_cmds[] = {
 };
 
 static gboolean
+matches_arg (NmCli *nmc, int *argc, char ***argv, const char *pattern, char **arg)
+{
+	char *opt = *argv[0];
+
+	if (nmc->return_value != NMC_RESULT_SUCCESS) {
+		/* Don't process further matches if there has been an error. */
+		return FALSE;
+	}
+
+	if (opt[1] == '-') {
+		/* We know one '-' was already seen by the caller.
+		 * Skip it if there's a second one*/
+		opt++;
+	}
+
+	if (arg) {
+		/* If there's a "=" separator, replace it with NUL so that matches()
+		 * works and consider the part after it to be the arguemnt's value. */
+		*arg = strchr (opt, '=');
+		if (*arg) {
+			**arg = '\0';
+			(*arg)++;
+		}
+	}
+
+	if (!matches (opt, pattern)) {
+		if (arg && *arg) {
+			/* Back off the replacement of "=". */
+			(*arg)--;
+			**arg = '=';
+		}
+		return FALSE;
+	}
+
+	if (arg && !*arg) {
+		/* We need a value, but the option didn't contain a "=<value>" part.
+		 * Proceed to the next argument. */
+		(*argc)--;
+		(*argv)++;
+		if (!*argc) {
+			g_string_printf (nmc->return_text, _("Error: missing argument for '%s' option."), opt);
+			nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
+			return FALSE;
+		}
+		*arg = *argv[0];
+	}
+
+	return TRUE;
+}
+
+static gboolean
 process_command_line (NmCli *nmc, int argc, char **argv)
 {
 	char *base;
@@ -209,26 +289,24 @@ process_command_line (NmCli *nmc, int argc, char **argv)
 
 	/* parse options */
 	while (argc) {
-		char *opt = argv[0];
-		if (opt[0] != '-')
+		char *value;
+
+		if (argv[0][0] != '-')
 			break;
 
 		if (argc == 1 && nmc->complete) {
-			nmc_complete_strings (opt, "--terse", "--pretty", "--mode", "--colors", "--escape",
+			nmc_complete_strings (argv[0], "--terse", "--pretty", "--mode", "--colors", "--escape",
 			                           "--fields", "--nocheck", "--get-values",
 			                            "--wait", "--version", "--help", NULL);
 		}
 
-		if (opt[1] == '-') {
-			opt++;
+		if (argv[0][1] == '-' && argv[0][2] == '\0') {
 			/* '--' ends options */
-			if (opt[1] == '\0') {
-				next_arg (nmc, &argc, &argv, NULL);
-				break;
-			}
+			next_arg (nmc, &argc, &argv, NULL);
+			break;
 		}
 
-		if (matches (opt, "-terse")) {
+		if (matches_arg (nmc, &argc, &argv, "-terse", NULL)) {
 			if (nmc->nmc_config.print_output == NMC_PRINT_TERSE) {
 				g_string_printf (nmc->return_text, _("Error: Option '--terse' is specified the second time."));
 				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
@@ -241,7 +319,7 @@ process_command_line (NmCli *nmc, int argc, char **argv)
 			}
 			else
 				nmc->nmc_config_mutable.print_output = NMC_PRINT_TERSE;
-		} else if (matches (opt, "-pretty")) {
+		} else if (matches_arg (nmc, &argc, &argv, "-pretty", NULL)) {
 			if (nmc->nmc_config.print_output == NMC_PRINT_PRETTY) {
 				g_string_printf (nmc->return_text, _("Error: Option '--pretty' is specified the second time."));
 				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
@@ -254,126 +332,86 @@ process_command_line (NmCli *nmc, int argc, char **argv)
 			}
 			else
 				nmc->nmc_config_mutable.print_output = NMC_PRINT_PRETTY;
-		} else if (matches (opt, "-mode")) {
+		} else if (matches_arg (nmc, &argc, &argv, "-mode", &value)) {
 			nmc->mode_specified = TRUE;
-			argc--;
-			argv++;
-			if (!argc) {
-				g_string_printf (nmc->return_text, _("Error: missing argument for '%s' option."), opt);
-				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
-				return FALSE;
-			}
 			if (argc == 1 && nmc->complete)
-				nmc_complete_strings (argv[0], "tabular", "multiline", NULL);
-			if (matches (argv[0], "tabular"))
+				complete_option_with_value (argv[0], value, "tabular", "multiline", NULL);
+			if (matches (value, "tabular"))
 				nmc->nmc_config_mutable.multiline_output = FALSE;
-			else if (matches (argv[0], "multiline"))
+			else if (matches (value, "multiline"))
 				nmc->nmc_config_mutable.multiline_output = TRUE;
 			else {
-				g_string_printf (nmc->return_text, _("Error: '%s' is not valid argument for '%s' option."), argv[0], opt);
-				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
-				return FALSE;
-			}
-		} else if (matches (opt, "-colors")) {
-			argc--;
-			argv++;
-			if (!argc) {
-				g_string_printf (nmc->return_text, _("Error: missing argument for '%s' option."), opt);
+				g_string_printf (nmc->return_text, _("Error: '%s' is not a valid argument for '%s' option."), value, argv[0]);
 				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
 				return FALSE;
 			}
+		} else if (matches_arg (nmc, &argc, &argv, "-colors", &value)) {
 			if (argc == 1 && nmc->complete)
-				nmc_complete_strings (argv[0], "yes", "no", "auto", NULL);
-			if (matches (argv[0], "auto"))
+				complete_option_with_value (argv[0], value, "yes", "no", "auto", NULL);
+			if (matches (value, "auto"))
 				nmc->nmc_config_mutable.use_colors = NMC_USE_COLOR_AUTO;
-			else if (matches (argv[0], "yes"))
+			else if (matches (value, "yes"))
 				nmc->nmc_config_mutable.use_colors = NMC_USE_COLOR_YES;
-			else if (matches (argv[0], "no"))
+			else if (matches (value, "no"))
 				nmc->nmc_config_mutable.use_colors = NMC_USE_COLOR_NO;
 			else {
-				g_string_printf (nmc->return_text, _("Error: '%s' is not valid argument for '%s' option."), argv[0], opt);
-				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
-				return FALSE;
-			}
-		} else if (matches (opt, "-escape")) {
-			argc--;
-			argv++;
-			if (!argc) {
-				g_string_printf (nmc->return_text, _("Error: missing argument for '%s' option."), opt);
+				g_string_printf (nmc->return_text, _("Error: '%s' is not valid argument for '%s' option."), value, argv[0]);
 				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
 				return FALSE;
 			}
+		} else if (matches_arg (nmc, &argc, &argv, "-escape", &value)) {
 			if (argc == 1 && nmc->complete)
-				nmc_complete_strings (argv[0], "yes", "no", NULL);
-			if (matches (argv[0], "yes"))
+				complete_option_with_value (argv[0], value, "yes", "no", NULL);
+			if (matches (value, "yes"))
 				nmc->nmc_config_mutable.escape_values = TRUE;
-			else if (matches (argv[0], "no"))
+			else if (matches (value, "no"))
 				nmc->nmc_config_mutable.escape_values = FALSE;
 			else {
-				g_string_printf (nmc->return_text, _("Error: '%s' is not valid argument for '%s' option."), argv[0], opt);
-				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
-				return FALSE;
-			}
-		} else if (matches (opt, "-fields")) {
-			argc--;
-			argv++;
-			if (!argc) {
-				g_string_printf (nmc->return_text, _("Error: fields for '%s' options are missing."), opt);
+				g_string_printf (nmc->return_text, _("Error: '%s' is not valid argument for '%s' option."), value, argv[0]);
 				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
 				return FALSE;
 			}
+		} else if (matches_arg (nmc, &argc, &argv, "-fields", &value)) {
 			if (argc == 1 && nmc->complete)
-				complete_fields (argv[0]);
-			nmc->required_fields = g_strdup (argv[0]);
-		} else if (matches (opt, "-get-values")) {
-			argc--;
-			argv++;
-			if (!argc) {
-				g_string_printf (nmc->return_text, _("Error: fields for '%s' options are missing."), opt);
-				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
-				return FALSE;
-			}
+				complete_fields (argv[0], value);
+			nmc->required_fields = g_strdup (value);
+		} else if (matches_arg (nmc, &argc, &argv, "-get-values", &value)) {
 			if (argc == 1 && nmc->complete)
-				complete_fields (argv[0]);
-			nmc->required_fields = g_strdup (argv[0]);
+				complete_fields (argv[0], value);
+			nmc->required_fields = g_strdup (value);
 			nmc->nmc_config_mutable.print_output = NMC_PRINT_TERSE;
 			/* We want fixed tabular mode here, but just set the mode specified and rely on the initialization
 			 * in nmc_init: in this way we allow use of "-m multiline" to swap the output mode also if placed
 			 * before the "-g <field>" option (-g may be still more practical and easy to remember than -t -f).
 			*/
 			nmc->mode_specified = TRUE;
-		} else if (matches (opt, "-nocheck")) {
+		} else if (matches_arg (nmc, &argc, &argv, "-nocheck", NULL)) {
 			/* ignore for backward compatibility */
-		} else if (matches (opt, "-wait")) {
+		} else if (matches_arg (nmc, &argc, &argv, "-wait", &value)) {
 			unsigned long timeout;
 
-			argc--;
-			argv++;
-			if (!argc) {
-				g_string_printf (nmc->return_text, _("Error: missing argument for '%s' option."), opt);
-				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
-				return FALSE;
-			}
-			if (!nmc_string_to_uint (argv[0], TRUE, 0, G_MAXINT, &timeout)) {
-				g_string_printf (nmc->return_text, _("Error: '%s' is not a valid timeout for '%s' option."),
-						 argv[0], opt);
+			if (!nmc_string_to_uint (value, TRUE, 0, G_MAXINT, &timeout)) {
+				g_string_printf (nmc->return_text, _("Error: '%s' is not a valid timeout."), value);
 				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
 				return FALSE;
 			}
 			nmc->timeout = (int) timeout;
-		} else if (matches (opt, "-version")) {
+		} else if (matches_arg (nmc, &argc, &argv, "-version", NULL)) {
 			if (!nmc->complete)
 				g_print (_("nmcli tool, version %s\n"), NMCLI_VERSION);
 			return NMC_RESULT_SUCCESS;
-		} else if (matches (opt, "-help")) {
+		} else if (matches_arg (nmc, &argc, &argv, "-help", NULL)) {
 			if (!nmc->complete)
 				usage ();
 			return NMC_RESULT_SUCCESS;
 		} else {
-			g_string_printf (nmc->return_text, _("Error: Option '%s' is unknown, try 'nmcli -help'."), opt);
-			nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
+			if (nmc->return_value == NMC_RESULT_SUCCESS) {
+				g_string_printf (nmc->return_text, _("Error: Option '%s' is unknown, try 'nmcli -help'."), argv[0]);
+				nmc->return_value = NMC_RESULT_ERROR_USER_INPUT;
+			}
 			return FALSE;
 		}
+
 		next_arg (nmc, &argc, &argv, NULL);
 	}
 
@@ -547,7 +585,9 @@ nmc_init (NmCli *nmc)
 static void
 nmc_cleanup (NmCli *nmc)
 {
-	if (nmc->client) g_object_unref (nmc->client);
+	pid_t ret;
+
+	g_clear_object (&nmc->client);
 
 	g_string_free (nmc->return_text, TRUE);
 
@@ -561,6 +601,15 @@ nmc_cleanup (NmCli *nmc)
 
 	g_free (nmc->required_fields);
 
+	if (nmc->pager_pid > 0) {
+		fclose (stdout);
+		fclose (stderr);
+		do {
+			ret = waitpid (nmc->pager_pid, NULL, 0);
+		} while (ret == -1 && errno == EINTR);
+		nmc->pager_pid = 0;
+	}
+
 	nmc_polkit_agent_fini (nmc);
 }
 
diff --git a/clients/cli/nmcli.h b/clients/cli/nmcli.h
index 71ddb05596..874bca214b 100644
--- a/clients/cli/nmcli.h
+++ b/clients/cli/nmcli.h
@@ -14,7 +14,7 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * Copyright 2010 - 2015 Red Hat, Inc.
+ * Copyright 2010 - 2017 Red Hat, Inc.
  */
 
 #ifndef NMC_NMCLI_H
@@ -129,6 +129,7 @@ typedef struct _NmCli {
 
 	NMCResultCode return_value;                       /* Return code of nmcli */
 	GString *return_text;                             /* Reason text */
+	pid_t pager_pid;                                  /* PID of a pager, if one was spawned */
 
 	int timeout;                                      /* Operation timeout */
 
diff --git a/clients/cli/utils.c b/clients/cli/utils.c
index f48d8639b9..117a33d62e 100644
--- a/clients/cli/utils.c
+++ b/clients/cli/utils.c
@@ -14,7 +14,8 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * Copyright 2010 - 2015 Red Hat, Inc.
+ * Copyright 2010 Lennart Poettering
+ * Copyright 2010 - 2017 Red Hat, Inc.
  */
 
 #include "nm-default.h"
@@ -28,6 +29,7 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
+#include <sys/prctl.h>
 
 #include "nm-client-utils.h"
 #include "nm-meta-setting-access.h"
@@ -122,7 +124,7 @@ use_colors (NmcColorOption color_option)
 
 		if (G_UNLIKELY (cached == NMC_USE_COLOR_AUTO)) {
 			if (   g_strcmp0 (g_getenv ("TERM"), "dumb") == 0
-				|| !isatty (fileno (stdout)))
+				|| !isatty (STDOUT_FILENO))
 				cached = NMC_USE_COLOR_NO;
 			else
 				cached = NMC_USE_COLOR_YES;
@@ -1450,6 +1452,109 @@ nmc_print (const NmcConfig *nmc_config,
 
 /*****************************************************************************/
 
+static void
+pager_fallback (void)
+{
+	char buf[64];
+	int rb;
+
+	do {
+		rb = read (STDIN_FILENO, buf, sizeof (buf));
+		if (rb == -1) {
+			if (errno == EINTR) {
+				continue;
+			} else {
+				g_printerr (_("Error reading nmcli output: %s\n"), strerror (errno));
+				_exit(EXIT_FAILURE);
+			}
+		}
+		if (write (STDOUT_FILENO, buf, rb) == -1) {
+			g_printerr (_("Error writing nmcli output: %s\n"), strerror (errno));
+			_exit(EXIT_FAILURE);
+		}
+	} while (rb > 0);
+
+	_exit(EXIT_SUCCESS);
+}
+
+void
+nmc_terminal_spawn_pager (const NmcConfig *nmc_config)
+{
+	const char *pager = getenv ("PAGER");
+	pid_t parent_pid;
+	int fd[2];
+
+	if (   nm_cli.pager_pid > 0
+	    || nmc_config->print_output == NMC_PRINT_TERSE
+	    || !use_colors (nmc_config->use_colors)
+	    || g_strcmp0 (pager, "") == 0)
+		return;
+
+	if (pipe (fd) == -1) {
+		g_printerr (_("Failed to create pager pipe: %s\n"), strerror (errno));
+		return;
+	}
+
+	parent_pid = getpid ();
+
+	nm_cli.pager_pid = fork ();
+	if (nm_cli.pager_pid == -1) {
+		g_printerr (_("Failed to fork pager: %s\n"), strerror (errno));
+		close (fd[0]);
+		close (fd[1]);
+		return;
+	}
+
+	/* In the child start the pager */
+	if (nm_cli.pager_pid == 0) {
+		dup2 (fd[0], STDIN_FILENO);
+		close (fd[0]);
+		close (fd[1]);
+
+		setenv ("LESS", "FRSXMK", 1);
+		setenv ("LESSCHARSET", "utf-8", 1);
+
+		/* Make sure the pager goes away when the parent dies */
+		if (prctl (PR_SET_PDEATHSIG, SIGTERM) < 0)
+			_exit (EXIT_FAILURE);
+
+		/* Check whether our parent died before we were able
+		 * to set the death signal */
+		if (getppid () != parent_pid)
+			_exit (EXIT_SUCCESS);
+
+		if (pager) {
+			execlp (pager, pager, NULL);
+			execl ("/bin/sh", "sh", "-c", pager, NULL);
+		}
+
+		/* Debian's alternatives command for pagers is
+		 * called 'pager'. Note that we do not call
+		 * sensible-pagers here, since that is just a
+		 * shell script that implements a logic that
+		 * is similar to this one anyway, but is
+		 * Debian-specific. */
+		execlp ("pager", "pager", NULL);
+
+		execlp ("less", "less", NULL);
+		execlp ("more", "more", NULL);
+
+		pager_fallback ();
+		/* not reached */
+	}
+
+	/* Return in the parent */
+	if (dup2 (fd[1], STDOUT_FILENO) < 0)
+		g_printerr (_("Failed to duplicate pager pipe: %s\n"), strerror (errno));
+	if (dup2 (fd[1], STDERR_FILENO) < 0)
+		g_printerr (_("Failed to duplicate pager pipe: %s\n"), strerror (errno));
+
+	close (fd[0]);
+	close (fd[1]);
+}
+
+/*****************************************************************************/
+
 static const char *
 get_value_to_print (NmcColorOption color_option,
                     const NmcOutputField *field,
@@ -1514,6 +1619,9 @@ print_required_fields (const NmcConfig *nmc_config,
 	gboolean field_names = of_flags & NMC_OF_FLAG_FIELD_NAMES;
 	gboolean section_prefix = of_flags & NMC_OF_FLAG_SECTION_PREFIX;
 
+	/* Optionally start paging the output. */
+	nmc_terminal_spawn_pager (nmc_config);
+
 	/* --- Main header --- */
 	if ((main_header_add || main_header_only) && pretty) {
 		gs_free char *line = NULL;
diff --git a/clients/cli/utils.h b/clients/cli/utils.h
index 32a638af46..1724d4391e 100644
--- a/clients/cli/utils.h
+++ b/clients/cli/utils.h
@@ -14,7 +14,7 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * Copyright 2010 - 2015 Red Hat, Inc.
+ * Copyright 2010 - 2017 Red Hat, Inc.
  */
 
 #ifndef NMC_UTILS_H
@@ -40,6 +40,8 @@ gboolean nmc_parse_args (nmc_arg_t *arg_arr, gboolean last, int *argc, char ***a
 char *ssid_to_hex (const char *str, gsize len);
 void nmc_terminal_erase_line (void);
 void nmc_terminal_show_progress (const char *str);
+void nmc_terminal_spawn_pager (const NmcConfig *nmc_config);
+gboolean nmc_term_use_colors (NmcColorOption color_option);
 const char *nmc_term_color_sequence (NMMetaTermColor color);
 const char *nmc_term_format_sequence (NMMetaTermFormat format);
 NMMetaTermColor nmc_term_color_parse_string (const char *str, GError **error);