1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
22 #include <sys/types.h>
26 #include <sys/prctl.h>
32 static pid_t pager_pid = 0;
34 void pager_open(void) {
42 if (isatty(STDOUT_FILENO) <= 0)
45 if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER")))
46 if (!*pager || streq(pager, "cat"))
49 /* Determine and cache number of columns before we spawn the
50 * pager so that we get the value from the actual tty */
54 log_error("Failed to create pager pipe: %m");
58 parent_pid = getpid();
62 log_error("Failed to fork pager: %m");
67 /* In the child start the pager */
70 dup2(fd[0], STDIN_FILENO);
73 setenv("LESS", "FRSX", 0);
75 /* Make sure the pager goes away when the parent dies */
76 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
79 /* Check whether our parent died before we were able
80 * to set the death signal */
81 if (getppid() != parent_pid)
85 execlp(pager, pager, NULL);
86 execl("/bin/sh", "sh", "-c", pager, NULL);
89 /* Debian's alternatives command for pagers is
90 * called 'pager'. Note that we do not call
91 * sensible-pagers here, since that is just a
92 * shell script that implements a logic that
93 * is similar to this one anyway, but is
95 execlp("pager", "pager", NULL);
97 execlp("less", "less", NULL);
98 execlp("more", "more", NULL);
99 execlp("cat", "cat", NULL);
101 log_error("Unable to execute pager: %m");
105 /* Return in the parent */
106 if (dup2(fd[1], STDOUT_FILENO) < 0)
107 log_error("Failed to duplicate pager pipe: %m");
112 void pager_close(void) {
117 /* Inform pager that we are done */
119 kill(pager_pid, SIGCONT);
120 wait_for_terminate(pager_pid, NULL);