[systemd-devel] [PATCH v2] systemctl: implement auto-pager a la git
Miklos Vajna
vmiklos at frugalware.org
Sun Jan 2 16:32:17 PST 2011
---
On Sun, Jan 02, 2011 at 09:21:50PM +0100, Tollef Fog Heen <tfheen at err.no> wrote:
> | Not all distributions have such a command, while all distributions have
> | less packaged. What about making it a configure option, but let the
> | default be 'less'? Then Debian and other packages can use
> | --with-pager=pager or so.
>
> Sounds fine to me.
Added --with-default-pager.
> It might be useful to rather just special-case tty output, like ps does,
> where piping to a process will not limit the length of the output, so
> you can do ??ps ax | cat?? which then doesn't cut off at $COLUMNS char
> rather than special-casing cat. If people do foo | cat, they should get
> what they asked for, IMO.
Makes sense, removed.
TODO | 2 --
configure.ac | 10 ++++++++++
man/systemctl.xml | 7 +++++++
src/systemctl.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 69 insertions(+), 2 deletions(-)
diff --git a/TODO b/TODO
index 21f06a6..c9a7617 100644
--- a/TODO
+++ b/TODO
@@ -67,8 +67,6 @@
* suspend, resume
-* systemctl auto-pager a la git
-
* readahead: btrfs/LVM SSD detection
* when processes remain in a service even though the start command failed enter active
diff --git a/configure.ac b/configure.ac
index 4f77aa8..3108018 100644
--- a/configure.ac
+++ b/configure.ac
@@ -396,9 +396,17 @@ AC_ARG_WITH([syslog-service],
[SPECIAL_SYSLOG_SERVICE="$withval"],
[])
+DEFAULT_PAGER=less
+AC_ARG_WITH([default-pager],
+ [AS_HELP_STRING([--with-default-pager=COMMAND],
+ [Specify the name of the default pager @<:@default=less@:>@])],
+ [DEFAULT_PAGER="$withval"],
+ [])
+
AC_SUBST(SYSTEM_SYSVINIT_PATH)
AC_SUBST(SYSTEM_SYSVRCND_PATH)
AC_SUBST(SPECIAL_SYSLOG_SERVICE)
+AC_SUBST(DEFAULT_PAGER)
AC_SUBST(M4_DISTRO_FLAG)
if test "x${SYSTEM_SYSVINIT_PATH}" != "x" -a "x${SYSTEM_SYSVRCND_PATH}" != "x"; then
@@ -421,6 +429,7 @@ AM_CONDITIONAL(TARGET_SLACKWARE, test x"$with_distro" = xslackware)
AM_CONDITIONAL(TARGET_FRUGALWARE, test x"$with_distro" = xfrugalware)
AC_DEFINE_UNQUOTED(SPECIAL_SYSLOG_SERVICE, ["$SPECIAL_SYSLOG_SERVICE"], [Syslog service name])
+AC_DEFINE_UNQUOTED(DEFAULT_PAGER, ["$DEFAULT_PAGER"], [Default pager command])
AC_ARG_WITH([dbuspolicydir],
AS_HELP_STRING([--with-dbuspolicydir=DIR], [D-Bus policy directory]),
@@ -476,6 +485,7 @@ echo "
SysV init scripts: ${SYSTEM_SYSVINIT_PATH}
SysV rc?.d directories: ${SYSTEM_SYSVRCND_PATH}
Syslog service: ${SPECIAL_SYSLOG_SERVICE}
+ Default pager : ${DEFAULT_PAGER}
Gtk: ${have_gtk}
libcryptsetup: ${have_libcryptsetup}
tcpwrap: ${have_tcpwrap}
diff --git a/man/systemctl.xml b/man/systemctl.xml
index 6b05e95..c21ed85 100644
--- a/man/systemctl.xml
+++ b/man/systemctl.xml
@@ -171,6 +171,13 @@
enqueued.</para></listitem> </varlistentry>
<varlistentry>
+ <term><option>--no-pager</option></term>
+
+ <listitem><para>Do not pipe output into a
+ pager.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
<term><option>--system</option></term>
<listitem><para>Talk to the systemd
diff --git a/src/systemctl.c b/src/systemctl.c
index 4768fb2..57a1b4f 100644
--- 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 +5282,48 @@ static int runlevel_main(void) {
return 0;
}
+static void pager_open(void) {
+ pid_t pid;
+ int fd[2];
+ const char *pager = getenv("PAGER");
+
+ if (!on_tty() || arg_no_pager)
+ return;
+ if (!pager)
+ pager = DEFAULT_PAGER;
+ else if (!*pager)
+ return;
+
+ if (pipe(fd) < 0)
+ return;
+ pid = fork();
+ if (pid < 0) {
+ close(fd[0]);
+ close(fd[1]);
+ return;
+ }
+
+ /* Return in the child */
+ if (!pid) {
+ dup2(fd[1], 1);
+ close(fd[0]);
+ close(fd[1]);
+ return;
+ }
+
+ /* The original process turns into the PAGER */
+ dup2(fd[0], 0);
+ close(fd[0]);
+ close(fd[1]);
+
+ setenv("LESS", "FRSX", 0);
+ execlp(pager, pager, NULL);
+ execl("/bin/sh", "sh", "-c", pager, NULL);
+
+ log_error("unable to execute pager '%s'", pager);
+ _exit(EXIT_FAILURE);
+}
+
int main(int argc, char*argv[]) {
int r, retval = EXIT_FAILURE;
DBusConnection *bus = NULL;
@@ -5291,6 +5341,8 @@ 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) {
--
1.7.3.4
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