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Diffstat (limited to 'man/sd_watchdog_enabled.xml')
| -rw-r--r-- | man/sd_watchdog_enabled.xml | 53 |
1 files changed, 36 insertions, 17 deletions
diff --git a/man/sd_watchdog_enabled.xml b/man/sd_watchdog_enabled.xml index 4164027640..462d7c6617 100644 --- a/man/sd_watchdog_enabled.xml +++ b/man/sd_watchdog_enabled.xml @@ -69,30 +69,37 @@ which the manager will act on the service if it did not get such a notification.</para> + <para>If the <varname>$WATCHDOG_USEC</varname> + environment variable is set, and the + <varname>$WATCHDOG_PID</varname> variable is unset or + set to the PID of the current process, the service + manager expects notifications from this process. The + manager will usually terminate a service when it does + not get a notification message within the specified + time after startup and after each previous message. It + is recommended that a daemon sends a keep-alive + notification message to the service manager every half + of the time returned here. Notification messages may + be sent with + <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry> + with a message string of + <literal>WATCHDOG=1</literal>.</para> + <para>If the <parameter>unset_environment</parameter> parameter is non-zero, <function>sd_watchdog_enabled()</function> will unset the <varname>$WATCHDOG_USEC</varname> and <varname>$WATCHDOG_PID</varname> environment variables - before returning (regardless of whether the function call - itself succeeded or not). Further calls to - <function>sd_watchdog_enabled()</function> will then - return with zero, but the variable is no longer - inherited by child processes.</para> + before returning (regardless of whether the function + call itself succeeded or not). Those variables are no + longer inherited by child processes. Further calls to + <function>sd_watchdog_enabled()</function> will also + return with zero.</para> <para>If the <parameter>usec</parameter> parameter is non-NULL, <function>sd_watchdog_enabled()</function> - will return the timeout in µs for the watchdog - logic. The service manager will usually terminate a - service when it did not get a notification message - within the specified time after startup and after each - previous message. It is recommended that a daemon - sends a keep-alive notification message to the service - manager every half of the time returned - here. Notification messages may be sent with - <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry> - with a message string of - <literal>WATCHDOG=1</literal>.</para> + will write the timeout in µs for the watchdog + logic to it.</para> <para>To enable service supervision with the watchdog logic, use <varname>WatchdogSec=</varname> in service @@ -126,7 +133,6 @@ of the current process, under the assumption that in that case, the variables were set for a different process further up the process tree.</para> - </refsect1> <refsect1> @@ -157,6 +163,19 @@ </refsect1> <refsect1> + <title>History</title> + + <para>The watchdog functionality and the + <varname>$WATCHDOG_USEC</varname> variable were + added in systemd-41.</para> + + <para><function>sd_watchdog_enabled()</function> + function was added in systemd-209. Since that version + the <varname>$WATCHDOG_PID</varname> variable is also + set.</para> + </refsect1> + + <refsect1> <title>See Also</title> <para> <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |