man: add more details for IMPORT, PROGRAM and RUN keys
967de8face added a note that I found very hard
to understand. Reword it, and also describe how IMPORT and PROGRAM are different
from RUN.
Minor markup adjustements too.This commit is contained in:
Zbigniew Jędrzejewski-Szmek
parent
ba60127df7
commit
12254ccab0
79
man/udev.xml
79
man/udev.xml
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@ -280,13 +280,17 @@
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<varlistentry>
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<term><varname>PROGRAM</varname></term>
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<listitem>
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<para>Execute a program to determine whether there
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is a match; the key is true if the program returns
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successfully. The device properties are made available to the
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executed program in the environment. The program's standard output
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is available in the <varname>RESULT</varname> key.</para>
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<para>This can only be used for very short-running foreground tasks. For details,
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see <varname>RUN</varname>.</para>
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<para>Execute a program to determine whether there is a match; the key is true if the program
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returns successfully. The device properties are made available to the executed program in the
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environment. The program's standard output is available in the <varname>RESULT</varname>
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key.</para>
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<para>This can only be used for very short-running foreground tasks. For details, see
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<varname>RUN</varname>.</para>
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<para>Note that multiple <varname>PROGRAM</varname> keys may be specified in one rule, and
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<literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as
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<literal>==</literal>.</para>
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</listitem>
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</varlistentry>
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@ -429,9 +433,14 @@
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<varlistentry>
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<term><varname>RUN{<replaceable>type</replaceable>}</varname></term>
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<listitem>
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<para>Add a program to the list of programs to be executed after
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processing all the rules for a specific event, depending on
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<literal>type</literal>:</para>
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<para>Specify a program to be executed after processing of all the rules for the event. With
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<literal>+=</literal>, this invocation is added to the list, and with <literal>=</literal> or
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<literal>:=</literal>, it replaces any previous contents of the list. Please note that both
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<literal>program</literal> and <literal>builtin</literal> types described below use a single
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list, so clearing the list with <literal>:=</literal> and <literal>=</literal> affects both
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types.</para>
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<para><replaceable>type</replaceable> may be:</para>
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<variablelist>
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<varlistentry>
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<term><literal>program</literal></term>
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@ -452,21 +461,21 @@
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</listitem>
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</varlistentry>
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</variablelist>
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<para>The program name and following arguments are separated by spaces.
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Single quotes can be used to specify arguments with spaces.</para>
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<para>This can only be used for very short-running foreground tasks. Running an
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event process for a long period of time may block all further events for
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this or a dependent device.</para>
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<para>Starting daemons or other long-running processes is not appropriate
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for udev; the forked processes, detached or not, will be unconditionally
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killed after the event handling has finished.</para>
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<para>Note that running programs that access the network or mount/unmount
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filesystems is not allowed inside of udev rules, due to the default sandbox
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that is enforced on <filename>systemd-udevd.service</filename>.</para>
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<para>Please also note that <literal>:=</literal> and <literal>=</literal> are clearing
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both, program and builtin commands.</para>
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<para>In order to activate long-running processes from udev rules, provide a service unit, and
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pull it in from a udev device using the <varname>SYSTEMD_WANTS</varname> device property. See
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<para>The program name and following arguments are separated by spaces. Single quotes can be
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used to specify arguments with spaces.</para>
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<para>This can only be used for very short-running foreground tasks. Running an event process for
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a long period of time may block all further events for this or a dependent device.</para>
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<para>Note that running programs that access the network or mount/unmount filesystems is not
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allowed inside of udev rules, due to the default sandbox that is enforced on
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<filename>systemd-udevd.service</filename>.</para>
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<para>Starting daemons or other long-running processes is not allowed; the forked processes,
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detached or not, will be unconditionally killed after the event handling has finished. In order
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to activate long-running processes from udev rules, provide a service unit and pull it in from a
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udev device using the <varname>SYSTEMD_WANTS</varname> device property. See
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<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details.</para>
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</listitem>
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@ -489,8 +498,9 @@
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<varlistentry>
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<term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term>
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<listitem>
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<para>Import a set of variables as device properties,
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depending on <literal>type</literal>:</para>
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<para>Import a set of variables as device properties, depending on
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<replaceable>type</replaceable>:</para>
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<variablelist>
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<varlistentry>
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<term><literal>program</literal></term>
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@ -542,8 +552,14 @@
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</listitem>
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</varlistentry>
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</variablelist>
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<para>This can only be used for very short-running foreground tasks. For details
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see <option>RUN</option>.</para>
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<para>This can only be used for very short-running foreground tasks. For details see
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<option>RUN</option>.</para>
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<para>Note that multiple <varname>IMPORT{}</varname> keys may be specified in one rule, and
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<literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as
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<literal>==</literal>. The key is true if the import is successful, unless <literal>!=</literal>
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is used as the operator which causes the key to be true if the import failed.</para>
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</listitem>
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</varlistentry>
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@ -633,9 +649,8 @@
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<varlistentry>
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<term><option>$number</option>, <option>%n</option></term>
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<listitem>
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<para>The kernel number for this device. For example,
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<literal>sda3</literal> has kernel number <literal>3</literal>.
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</para>
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<para>The kernel number for this device. For example, <literal>sda3</literal> has kernel number
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3.</para>
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</listitem>
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</varlistentry>
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