systemctl: try harder to find a suitable pager

[elogind.git] / src / systemctl.c

diff --git a/src/systemctl.c b/src/systemctl.c
index 4768fb20ad24053ab1b5eeda33818a2863c4af41..8a6277e75c62a941822ba7a8bd7313788371e456 100644 (file)
--- a/src/systemctl.c
+++ b/src/systemctl.c
@@ -65,6 +65,7 @@ static bool arg_user = false;
 static bool arg_global = false;
 static bool arg_immediate = false;
 static bool arg_no_block = false;
+static bool arg_no_pager = false;
 static bool arg_no_wtmp = false;
 static bool arg_no_sync = false;
 static bool arg_no_wall = false;
@@ -4110,6 +4111,7 @@ static int systemctl_help(void) {
                "                      pending\n"
                "  -q --quiet          Suppress output\n"
                "     --no-block       Do not wait until operation finished\n"
+               "     --no-pager       Do not pipe output into a pager.\n"
                "     --system         Connect to system manager\n"
                "     --user           Connect to user service manager\n"
                "     --order          When generating graph for dot, show only order\n"
@@ -4249,6 +4251,7 @@ static int systemctl_parse_argv(int argc, char *argv[]) {
                 ARG_SYSTEM,
                 ARG_GLOBAL,
                 ARG_NO_BLOCK,
+                ARG_NO_PAGER,
                 ARG_NO_WALL,
                 ARG_ORDER,
                 ARG_REQUIRE,
@@ -4272,6 +4275,7 @@ static int systemctl_parse_argv(int argc, char *argv[]) {
                 { "system",    no_argument,       NULL, ARG_SYSTEM    },
                 { "global",    no_argument,       NULL, ARG_GLOBAL    },
                 { "no-block",  no_argument,       NULL, ARG_NO_BLOCK  },
+                { "no-pager",  no_argument,       NULL, ARG_NO_PAGER  },
                 { "no-wall",   no_argument,       NULL, ARG_NO_WALL   },
                 { "quiet",     no_argument,       NULL, 'q'           },
                 { "order",     no_argument,       NULL, ARG_ORDER     },
@@ -4348,6 +4352,10 @@ static int systemctl_parse_argv(int argc, char *argv[]) {
                         arg_no_block = true;
                         break;
 
+                case ARG_NO_PAGER:
+                        arg_no_pager = true;
+                        break;
+
                 case ARG_NO_WALL:
                         arg_no_wall = true;
                         break;
@@ -5274,6 +5282,59 @@ static int runlevel_main(void) {
         return 0;
 }
 
+static void pager_open(void) {
+        pid_t pid;
+        int fd[2];
+        const char *pager;
+
+        if (!on_tty() || arg_no_pager)
+                return;
+
+        if ((pager = getenv("PAGER")))
+                if (!*pager || streq(pager, "cat"))
+                        return;
+
+        if (pipe(fd) < 0) {
+                log_error("Failed to create pager pipe: %m");
+                return;
+        }
+
+        pid = fork();
+        if (pid < 0) {
+                log_error("Failed to fork pager: %m");
+                close_pipe(fd);
+                return;
+        }
+
+        /* The original process turns into the PAGER */
+        if (pid != 0) {
+
+                dup2(fd[0], STDIN_FILENO);
+                close_pipe(fd);
+
+                if (!getenv("LESS"))
+                        setenv("LESS", "FRSX", 0);
+
+                if (pager) {
+                        execlp(pager, pager, NULL);
+                        execl("/bin/sh", "sh", "-c", pager, NULL);
+                } else {
+                        execlp("sensible-pager", "sensible-pager", NULL);
+                        execlp("less", "less", NULL);
+                        execlp("more", "more", NULL);
+                }
+
+                log_error("Unable to execute pager: %m");
+                _exit(EXIT_FAILURE);
+        }
+
+        /* Return in the child */
+        if (dup2(fd[1], STDOUT_FILENO) < 0)
+                log_error("Failed to duplicate pager pipe: %m");
+
+        close_pipe(fd);
+}
+
 int main(int argc, char*argv[]) {
         int r, retval = EXIT_FAILURE;
         DBusConnection *bus = NULL;
@@ -5291,6 +5352,8 @@ int main(int argc, char*argv[]) {
                 goto finish;
         }
 
+        pager_open();
+
         /* /sbin/runlevel doesn't need to communicate via D-Bus, so
          * let's shortcut this */
         if (arg_action == ACTION_RUNLEVEL) {