HDB UUCP lock file format. The HDB format is to store the process
identifier (PID) as a ten byte ASCII decimal number, with a trailing
newline. For example, if process 1230 holds a lock file, it would
contain the eleven characters: space, space, space, space, space,
space, one, two, three, zero, and newline.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARLOGLOGFILESANDDIRECTORIES"
>/var/log : Log files and directories</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE43"
>Purpose</A
></H3
><P
>This directory contains miscellaneous log files. Most logs must
be written to this directory or an appropriate subdirectory.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS24"
>Specific Options</A
></H3
><P
>The following files, or symbolic links to files, must be in
<TT
CLASS="FILENAME"
>/var/log</TT
>, if the corresponding subsystem is
installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN2410"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>File</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>lastlog</TT
></TD
><TD
>record of last login of each user</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>messages</TT
></TD
><TD
>system messages from <B
CLASS="COMMAND"
>syslogd</B
></TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>wtmp</TT
></TD
><TD
>record of all logins and logouts</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARMAILUSERMAILBOXFILES"
>/var/mail : User mailbox files (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE44"
>Purpose</A
></H3
><P
>The mail spool must be accessible through
<TT
CLASS="FILENAME"
>/var/mail</TT
> and the mail spool files must take the
form <TT
CLASS="FILENAME"
><username></TT
>.
<A
NAME="AEN2437"
HREF="#FTN.AEN2437"
><SPAN
CLASS="footnote"
>[41]</SPAN
></A
></P
><P
>User mailbox files in this location must be stored in the standard
UNIX mailbox format.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
> </TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>The logical location for this directory was changed from
<TT
CLASS="FILENAME"
>/var/spool/mail</TT
> in order to bring FHS in-line
with nearly every UNIX implementation. This change is important for
inter-operability since a single <TT
CLASS="FILENAME"
>/var/mail</TT
> is
often shared between multiple hosts and multiple UNIX implementations
(despite NFS locking issues).</P
><P
>It is important to note that there is no requirement to
physically move the mail spool to this location. However, programs
and header files must be changed to use
<TT
CLASS="FILENAME"
>/var/mail</TT
>. </P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VAROPTVARIABLEDATAFOROPT"
>/var/opt : Variable data for /opt</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE45"
>Purpose</A
></H3
><P
>Variable data of the packages in <TT
CLASS="FILENAME"
>/opt</TT
> must
be installed in <TT
CLASS="FILENAME"
>/var/opt/<subdir></TT
>, where
<TT
CLASS="FILENAME"
><subdir></TT
> is the name of the subtree in
<TT
CLASS="FILENAME"
>/opt</TT
> where the static data from an add-on
software package is stored, except where superseded by another file in
<TT
CLASS="FILENAME"
>/etc</TT
>. No structure is imposed on the internal
arrangement of <TT
CLASS="FILENAME"
>/var/opt/<subdir></TT
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
> </TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Refer to the rationale for <TT
CLASS="FILENAME"
>/opt</TT
>. </P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARRUNRUNTIMEVARIABLEDATA"
>/var/run : Run-time variable data</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE46"
>Purpose</A
></H3
><P
>This directory contains system information data describing the
system since it was booted. Files under this directory must be
cleared (removed or truncated as appropriate) at the beginning of the
boot process. Programs may have a subdirectory of
<TT
CLASS="FILENAME"
>/var/run</TT
>; this is encouraged for programs that
use more than one run-time file.
<A
NAME="AEN2469"
HREF="#FTN.AEN2469"
><SPAN
CLASS="footnote"
>[42]</SPAN
></A
>
Process identifier (PID) files, which were originally placed in
<TT
CLASS="FILENAME"
>/etc</TT
>, must be placed in
<TT
CLASS="FILENAME"
>/var/run</TT
>. The naming convention for PID files is
<TT
CLASS="FILENAME"
><program-name>.pid</TT
>. For example, the
<B
CLASS="COMMAND"
>crond</B
> PID file is named
<TT
CLASS="FILENAME"
>/var/run/crond.pid</TT
>.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS14"
>Requirements</A
></H3
><P
>The internal format of PID files remains unchanged. The file
must consist of the process identifier in ASCII-encoded decimal,
followed by a newline character. For example, if
<B
CLASS="COMMAND"
>crond</B
> was process number 25,
<TT
CLASS="FILENAME"
>/var/run/crond.pid</TT
> would contain three
characters: two, five, and newline.</P
><P
>Programs that read PID files should be somewhat flexible in what
they accept; i.e., they should ignore extra whitespace, leading
zeroes, absence of the trailing newline, or additional lines in the
PID file. Programs that create PID files should use the simple
specification located in the above paragraph.</P
><P
>The <TT
CLASS="FILENAME"
>utmp</TT
> file, which stores information
about who is currently using the system, is located in this
directory.</P
><P
>System programs that maintain transient UNIX-domain sockets must place
them in this directory.</P