man/tmpfiles.d.xml

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   7   Copyright 2010 Brandon Philips
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  22 <refentry id="tmpfiles.d">
  23
  24         <refentryinfo>
  25                 <title>tmpfiles.d</title>
  26                 <productname>systemd</productname>
  27
  28                 <authorgroup>
  29                         <author>
  30                                 <contrib>Documentation</contrib>
  31                                 <firstname>Brandon</firstname>
  32                                 <surname>Philips</surname>
  33                                 <email>brandon@ifup.org</email>
  34                         </author>
  35                 </authorgroup>
  36         </refentryinfo>
  37
  38         <refmeta>
  39                 <refentrytitle>tmpfiles.d</refentrytitle>
  40                 <manvolnum>5</manvolnum>
  41         </refmeta>
  42
  43         <refnamediv>
  44                 <refname>tmpfiles.d</refname>
  45                 <refpurpose>Configuration for creation, deletion and
  46                 cleaning of volatile and temporary files</refpurpose>
  47         </refnamediv>
  48
  49         <refsynopsisdiv>
  50                 <para><filename>/etc/tmpfiles.d/*.conf</filename></para>
  51                 <para><filename>/run/tmpfiles.d/*.conf</filename></para>
  52                 <para><filename>/usr/lib/tmpfiles.d/*.conf</filename></para>
  53         </refsynopsisdiv>
  54
  55         <refsect1>
  56                 <title>Description</title>
  57
  58                 <para><command>systemd-tmpfiles</command> uses the
  59                 configuration files from the above directories to describe the
  60                 creation, cleaning and removal of volatile and
  61                 temporary files and directories which usually reside
  62                 in directories such as <filename>/run</filename>
  63                 or <filename>/tmp</filename>.</para>
  64
  65                 <para>Volatile and temporary files and directories are
  66                 those located in <filename>/run</filename> (and its
  67                 alias <filename>/var/run</filename>),
  68                 <filename>/tmp</filename>,
  69                 <filename>/var/tmp</filename>, the API file systems
  70                 such as <filename>/sys</filename> or
  71                 <filename>/proc</filename>, as well as some other
  72                 directories below <filename>/var</filename>.</para>
  73
  74                 <para>System daemons frequently require private
  75                 runtime directories below <filename>/run</filename> to
  76                 place communication sockets and similar in. For these,
  77                 consider declaring them in their unit files using
  78                 <varname>RuntimeDirectory=</varname>
  79                 (see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details),
  80                 if this is feasible.</para>
  81         </refsect1>
  82
  83         <refsect1>
  84                 <title>Configuration Format</title>
  85
  86                 <para>Each configuration file shall be named in the
  87                 style of
  88                 <filename><replaceable>package</replaceable>.conf</filename>
  89                 or
  90                 <filename><replaceable>package</replaceable>-<replaceable>part</replaceable>.conf</filename>.
  91                 The second variant should be used when it is desirable
  92                 to make it easy to override just this part of
  93                 configuration.</para>
  94
  95                 <para>Files in <filename>/etc/tmpfiles.d</filename>
  96                 override files with the same name in
  97                 <filename>/usr/lib/tmpfiles.d</filename> and
  98                 <filename>/run/tmpfiles.d</filename>. Files in
  99                 <filename>/run/tmpfiles.d</filename> override files
 100                 with the same name in
 101                 <filename>/usr/lib/tmpfiles.d</filename>. Packages
 102                 should install their configuration files in
 103                 <filename>/usr/lib/tmpfiles.d</filename>. Files in
 104                 <filename>/etc/tmpfiles.d</filename> are reserved for
 105                 the local administrator, who may use this logic to
 106                 override the configuration files installed by vendor
 107                 packages. All configuration files are sorted by their
 108                 filename in lexicographic order, regardless of which
 109                 of the directories they reside in. If multiple files
 110                 specify the same path, the entry in the file with the
 111                 lexicographically earliest name will be applied, all
 112                 all other conflicting entries will be logged as
 113                 errors. When two lines are prefix and suffix of each
 114                 other, then the prefix is always processed first, the
 115                 suffix later. Otherwise, the files/directories are
 116                 processed in the order they are listed.</para>
 117
 118                 <para>If the administrator wants to disable a
 119                 configuration file supplied by the vendor, the
 120                 recommended way is to place a symlink to
 121                 <filename>/dev/null</filename> in
 122                 <filename>/etc/tmpfiles.d/</filename> bearing the
 123                 same filename.</para>
 124
 125                 <para>The configuration format is one line per path
 126                 containing type, path, mode, ownership, age, and argument
 127                 fields:</para>
 128
 129                 <programlisting>#Type Path        Mode UID  GID  Age Argument
 130 d    /run/user   0755 root root 10d -
 131 L    /tmp/foobar -    -    -    -   /dev/null</programlisting>
 132
 133                 <refsect2>
 134                         <title>Type</title>
 135
 136                         <para>The type consists of a single letter and
 137                         optionally an exclamation mark.</para>
 138
 139                         <para>The following line types are understood:</para>
 140
 141                         <variablelist>
 142                                 <varlistentry>
 143                                         <term><varname>f</varname></term>
 144                                         <listitem><para>Create a file if it does not exist yet. If the argument parameter is given, it will be written to the file.</para></listitem>
 145                                 </varlistentry>
 146
 147                                 <varlistentry>
 148                                         <term><varname>F</varname></term>
 149                                         <listitem><para>Create or truncate a file. If the argument parameter is given, it will be written to the file.</para></listitem>
 150                                 </varlistentry>
 151
 152                                 <varlistentry>
 153                                         <term><varname>w</varname></term>
 154                                         <listitem><para>Write the argument parameter to a file, if the file exists.
 155                                             Lines of this type accept shell-style globs in place of normal path
 156                                             names. The argument parameter will be written without a trailing
 157                                             newline. C-style backslash escapes are interpreted.</para></listitem>
 158                                 </varlistentry>
 159
 160                                 <varlistentry>
 161                                         <term><varname>d</varname></term>
 162                                         <listitem><para>Create a directory if it does not exist yet.</para></listitem>
 163                                 </varlistentry>
 164
 165                                 <varlistentry>
 166                                         <term><varname>D</varname></term>
 167                                         <listitem><para>Create or empty a directory.</para></listitem>
 168                                 </varlistentry>
 169
 170                                 <varlistentry>
 171                                         <term><varname>p</varname></term>
 172                                         <term><varname>p+</varname></term>
 173                                         <listitem><para>Create a named
 174                                         pipe (FIFO) if it does not
 175                                         exist yet. If suffixed with
 176                                         <varname>+</varname> and a
 177                                         file already exists where the
 178                                         pipe is to be created, it will
 179                                         be removed and be replaced by
 180                                         the pipe.</para></listitem>
 181                                 </varlistentry>
 182
 183                                 <varlistentry>
 184                                         <term><varname>L</varname></term>
 185                                         <term><varname>L+</varname></term>
 186                                         <listitem><para>Create a
 187                                         symlink if it does not exist
 188                                         yet. If suffixed with
 189                                         <varname>+</varname> and a
 190                                         file already exists where the
 191                                         symlink is to be created, it
 192                                         will be removed and be
 193                                         replaced by the
 194                                         symlink. If the argument is omitted,
 195                                         symlinks to files with the same name
 196                                         residing in the directory
 197                                         <filename>/usr/share/factory/</filename>
 198                                         are created.</para></listitem>
 199                                 </varlistentry>
 200
 201                                 <varlistentry>
 202                                         <term><varname>c</varname></term>
 203                                         <term><varname>c+</varname></term>
 204                                         <listitem><para>Create a
 205                                         character device node if it
 206                                         does not exist yet. If
 207                                         suffixed with
 208                                         <varname>+</varname> and a
 209                                         file already exists where the
 210                                         device node is to be created,
 211                                         it will be removed and be
 212                                         replaced by the device
 213                                         node.</para></listitem>
 214                                 </varlistentry>
 215
 216                                 <varlistentry>
 217                                         <term><varname>b</varname></term>
 218                                         <term><varname>b+</varname></term>
 219                                         <listitem><para>Create a block
 220                                         device node if it does not
 221                                         exist yet. If suffixed with
 222                                         <varname>+</varname> and a
 223                                         file already exists where the
 224                                         device node is to be created,
 225                                         it will be removed and be
 226                                         replaced by the device
 227                                         node.</para></listitem>
 228                                 </varlistentry>
 229
 230                                 <varlistentry>
 231                                         <term><varname>C</varname></term>
 232                                         <listitem><para>Recursively
 233                                         copy a file or directory, if
 234                                         the destination files or
 235                                         directories do not exist
 236                                         yet. Note that this command
 237                                         will not descend into
 238                                         subdirectories if the
 239                                         destination directory already
 240                                         exists. Instead, the entire
 241                                         copy operation is
 242                                         skipped. If the argument is omitted,
 243                                         files from the source directory
 244                                         <filename>/usr/share/factory/</filename>
 245                                         with the same name are copied.</para></listitem>
 246                                 </varlistentry>
 247
 248                                 <varlistentry>
 249                                         <term><varname>x</varname></term>
 250                                         <listitem><para>Ignore a path
 251                                         during cleaning. Use this type
 252                                         to exclude paths from clean-up
 253                                         as controlled with the Age
 254                                         parameter. Note that lines of
 255                                         this type do not influence the
 256                                         effect of <varname>r</varname>
 257                                         or <varname>R</varname> lines.
 258                                         Lines of this type accept
 259                                         shell-style globs in place of
 260                                         normal path names.
 261                                         </para></listitem>
 262                                 </varlistentry>
 263
 264                                 <varlistentry>
 265                                         <term><varname>X</varname></term>
 266                                         <listitem><para>Ignore a path
 267                                         during cleaning. Use this type
 268                                         to exclude paths from clean-up
 269                                         as controlled with the Age
 270                                         parameter. Unlike
 271                                         <varname>x</varname>, this
 272                                         parameter will not exclude the
 273                                         content if path is a
 274                                         directory, but only directory
 275                                         itself. Note that lines of
 276                                         this type do not influence the
 277                                         effect of <varname>r</varname>
 278                                         or <varname>R</varname> lines.
 279                                         Lines of this type accept
 280                                         shell-style globs in place of
 281                                         normal path names.
 282                                         </para></listitem>
 283                                 </varlistentry>
 284
 285                                 <varlistentry>
 286                                         <term><varname>r</varname></term>
 287                                         <listitem><para>Remove a file
 288                                         or directory if it exists.
 289                                         This may not be used to remove
 290                                         non-empty directories, use
 291                                         <varname>R</varname> for that.
 292                                         Lines of this type accept
 293                                         shell-style globs in place of
 294                                         normal path
 295                                         names.</para></listitem>
 296                                 </varlistentry>
 297
 298                                 <varlistentry>
 299                                         <term><varname>R</varname></term>
 300                                         <listitem><para>Recursively
 301                                         remove a path and all its
 302                                         subdirectories (if it is a
 303                                         directory). Lines of this type
 304                                         accept shell-style globs in
 305                                         place of normal path
 306                                         names.</para></listitem>
 307                                 </varlistentry>
 308
 309                                 <varlistentry>
 310                                         <term><varname>z</varname></term>
 311                                         <listitem><para>Adjust the
 312                                         access mode, group and user,
 313                                         and restore the SELinux security
 314                                         context of a file or directory,
 315                                         if it exists. Lines of this
 316                                         type accept shell-style globs
 317                                         in place of normal path names.
 318                                         </para></listitem>
 319                                 </varlistentry>
 320
 321                                 <varlistentry>
 322                                         <term><varname>Z</varname></term>
 323                                         <listitem><para>Recursively
 324                                         set the access mode, group and
 325                                         user, and restore the SELinux
 326                                         security context of a file or
 327                                         directory if it exists, as
 328                                         well as of its subdirectories
 329                                         and the files contained
 330                                         therein (if applicable). Lines
 331                                         of this type accept
 332                                         shell-style globs in place of
 333                                         normal path
 334                                         names.</para></listitem>
 335                                 </varlistentry>
 336                         </variablelist>
 337
 338                         <para>If the exclamation mark is used, this
 339                         line is only safe of execute during boot, and
 340                         can break a running system. Lines without the
 341                         exclamation mark are presumed to be safe to
 342                         execute at any time, e.g. on package upgrades.
 343                         <command>systemd-tmpfiles</command> will
 344                         execute line with an exclamation mark only if
 345                         option <option>--boot</option> is given.
 346                         </para>
 347
 348                         <para>For example:
 349                         <programlisting># Make sure these are created by default so that nobody else can
 350 d /tmp/.X11-unix 1777 root root 10d
 351
 352 # Unlink the X11 lock files
 353 r! /tmp/.X[0-9]*-lock</programlisting>
 354                         The second line in contrast to the first one
 355                         would break a running system, and will only be
 356                         executed with <option>--boot</option>.</para>
 357                 </refsect2>
 358
 359                 <refsect2>
 360                         <title>Path</title>
 361
 362                         <para>The file system path specification supports simple specifier
 363                         expansion. The following expansions are
 364                         understood:</para>
 365
 366                         <table>
 367                                 <title>Specifiers available</title>
 368                                 <tgroup cols='3' align='left' colsep='1' rowsep='1'>
 369                                         <colspec colname="spec" />
 370                                         <colspec colname="mean" />
 371                                         <colspec colname="detail" />
 372                                         <thead>
 373                                                 <row>
 374                                                         <entry>Specifier</entry>
 375                                                         <entry>Meaning</entry>
 376                                                         <entry>Details</entry>
 377                                                 </row>
 378                                         </thead>
 379                                         <tbody>
 380                                                 <row>
 381                                                         <entry><literal>%m</literal></entry>
 382                                                         <entry>Machine ID</entry>
 383                                                         <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
 384                                                 </row>
 385                                                 <row>
 386                                                         <entry><literal>%b</literal></entry>
 387                                                         <entry>Boot ID</entry>
 388                                                         <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
 389                                                 </row>
 390                                                 <row>
 391                                                         <entry><literal>%H</literal></entry>
 392                                                         <entry>Host name</entry>
 393                                                         <entry>The hostname of the running system.</entry>
 394                                                 </row>
 395                                                 <row>
 396                                                         <entry><literal>%v</literal></entry>
 397                                                         <entry>Kernel release</entry>
 398                                                         <entry>Identical to <command>uname -r</command> output.</entry>
 399                                                 </row>
 400                                                 <row>
 401                                                         <entry><literal>%%</literal></entry>
 402                                                         <entry>Escaped %</entry>
 403                                                         <entry>Single percent sign.</entry>
 404                                                 </row>
 405                                         </tbody>
 406                                 </tgroup>
 407                         </table>
 408                 </refsect2>
 409
 410                 <refsect2>
 411                         <title>Mode</title>
 412
 413                         <para>The file access mode to use when
 414                         creating this file or directory. If omitted or
 415                         when set to -, the default is used: 0755 for
 416                         directories, 0644 for all other file objects.
 417                         For <varname>z</varname>, <varname>Z</varname>
 418                         lines, if omitted or when set to
 419                         <literal>-</literal>, the file access mode
 420                         will not be modified. This parameter is
 421                         ignored for <varname>x</varname>,
 422                         <varname>r</varname>, <varname>R</varname>,
 423                         <varname>L</varname> lines.</para>
 424
 425                         <para>Optionally, if prefixed with
 426                         <literal>~</literal>, the access mode is masked
 427                         based on the already set access bits for
 428                         existing file or directories: if the existing
 429                         file has all executable bits unset, all
 430                         executable bits are removed from the new
 431                         access mode, too. Similarly, if all read bits
 432                         are removed from the old access mode, they will
 433                         be removed from the new access mode too, and
 434                         if all write bits are removed, they will be
 435                         removed from the new access mode too. In
 436                         addition, the sticky/SUID/SGID bit is removed unless
 437                         applied to a directory. This
 438                         functionality is particularly useful in
 439                         conjunction with <varname>Z</varname>.</para>
 440                 </refsect2>
 441
 442                 <refsect2>
 443                         <title>UID, GID</title>
 444
 445                         <para>The user and group to use for this file
 446                         or directory. This may either be a numeric
 447                         user/group ID or a user or group name. If
 448                         omitted or when set to <literal>-</literal>,
 449                         the default 0 (root) is used. For
 450                         <varname>z</varname>, <varname>Z</varname>
 451                         lines, when omitted or when set to -, the file
 452                         ownership will not be modified. These
 453                         parameters are ignored for
 454                         <varname>x</varname>, <varname>r</varname>,
 455                         <varname>R</varname>, <varname>L</varname>
 456                         lines.</para>
 457                 </refsect2>
 458
 459                 <refsect2>
 460                         <title>Age</title>
 461                         <para>The date field, when set, is used to
 462                         decide what files to delete when cleaning. If
 463                         a file or directory is older than the current
 464                         time minus the age field, it is deleted. The
 465                         field format is a series of integers each
 466                         followed by one of the following
 467                         postfixes for the respective time units:</para>
 468
 469                         <variablelist>
 470                                 <varlistentry>
 471                                 <term><varname>s</varname></term>
 472                                 <term><varname>min</varname></term>
 473                                 <term><varname>h</varname></term>
 474                                 <term><varname>d</varname></term>
 475                                 <term><varname>w</varname></term>
 476                                 <term><varname>ms</varname></term>
 477                                 <term><varname>m</varname></term>
 478                                 <term><varname>us</varname></term></varlistentry>
 479                         </variablelist>
 480
 481                         <para>If multiple integers and units are specified, the time
 482                         values are summed up. If an integer is given without a unit,
 483                         s is assumed.
 484                         </para>
 485
 486                         <para>When the age is set to zero, the files are cleaned
 487                         unconditionally.</para>
 488
 489                         <para>The age field only applies to lines
 490                         starting with <varname>d</varname>,
 491                         <varname>D</varname>, and
 492                         <varname>x</varname>. If omitted or set to
 493                         <literal>-</literal>, no automatic clean-up is
 494                         done.</para>
 495
 496                         <para>If the age field starts with a tilde
 497                         character <literal>~</literal>, the clean-up
 498                         is only applied to files and directories one
 499                         level inside the directory specified, but not
 500                         the files and directories immediately inside
 501                         it.</para>
 502                 </refsect2>
 503
 504                 <refsect2>
 505                         <title>Argument</title>
 506
 507                         <para>For <varname>L</varname> lines
 508                         determines the destination path of the
 509                         symlink. For <varname>c</varname>,
 510                         <varname>b</varname> determines the
 511                         major/minor of the device node, with major and
 512                         minor formatted as integers, separated by
 513                         <literal>:</literal>, e.g.
 514                         <literal>1:3</literal>. For
 515                         <varname>f</varname>, <varname>F</varname>,
 516                         and <varname>w</varname> may be used to
 517                         specify a short string that is written to the
 518                         file, suffixed by a newline. For
 519                         <varname>C</varname>, specifies the source file
 520                         or directory. Ignored for all other
 521                         lines.</para>
 522                 </refsect2>
 523
 524         </refsect1>
 525
 526         <refsect1>
 527                 <title>Example</title>
 528                 <example>
 529                         <title>/etc/tmpfiles.d/screen.conf example</title>
 530                         <para><command>screen</command> needs two directories created at boot with specific modes and ownership.</para>
 531
 532                         <programlisting>d /run/screens  1777 root root 10d
 533 d /run/uscreens 0755 root root 10d12h</programlisting>
 534                 </example>
 535                 <example>
 536                         <title>/etc/tmpfiles.d/abrt.conf example</title>
 537                         <para><command>abrt</command> needs a directory created at boot with specific mode and ownership and its content should be preserved.</para>
 538
 539                         <programlisting>d /var/tmp/abrt 0755 abrt abrt
 540 x /var/tmp/abrt/*</programlisting>
 541                 </example>
 542         </refsect1>
 543
 544         <refsect1>
 545                 <title>See Also</title>
 546                 <para>
 547                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 548                         <citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 549                         <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 550                         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 551                 </para>
 552         </refsect1>
 553
 554 </refentry>