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<A NAME="PAGENUM-1121"><P>Page 1121</P></A>
<P>There is a special syntax for creating the entire banks of devices for a hard drive:
</P>
<!-- CODE SNIP //-->
<PRE>
hd[a-d] 8/64
</PRE>
<!-- END CODE SNIP //-->
<P>What this means is as follows: Create hda, and eight partitions on
hda (hda1 through hda8), starting with minor number
0. Then create hdb, and eight partitions, starting with minor number 64. Then
hdc, and so on, with minor number 64*2 = 128—and so forth. These are automatically placed in the class
disk. The necessary groups and batches are created so you
can ask MAKEDEV to create hd or hda or hda1 and expect it to do the correct thing.
</P>
<P>Note that simple arithmetic is permitted for specifying the minor device number, as this often makes things much
clearer and less likely to be accidentally broken.
</P>
<P><B>
SEE ALSO
</B></P>
<P>
MAKEDEV(8), MAKEDEV.cfg(5)
</P>
<P>
Version 1.4, January 1995
</P>
<H3><A NAME="ch05_ 12">
environ
</A></H3>
<P>
environ—User environment.</P>
<P><B>
SYNOPSIS
</B></P>
<!-- CODE SNIP //-->
<PRE>
extern char **environ;
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B></P>
<P>An array of strings called the environment is made available by
exec(2) when a process begins. By convention, these
strings have the form name=value. Common examples are
</P>
<TABLE>
<TR><TD>
USER
</TD><TD>
The name of the logged-in user (used by some BSD-derived programs).
</TD></TR><TR><TD>
LOGNAME
</TD><TD>
The name of the logged-in user (used by some System-V derived programs).
</TD></TR><TR><TD>
HOME
</TD><TD>
A user's login directory, set by login(1) from the password filepasswd(5).
</TD></TR><TR><TD>
LANG
</TD><TD>
The name of a locale to use for locale categories when not overridden by LC_ALL or more <BR>
specific environment variables.
</TD></TR><TR><TD>
PATH
</TD><TD>
The sequence of directory prefixes that sh(1) and many other programs apply in searching <BR>
for a file known by an incomplete pathname. The prefixes are separated by :.
</TD></TR><TR><TD>
SHELL
</TD><TD>
The filename of the user's login shell.
</TD></TR><TR><TD>
TERM
</TD><TD>
The terminal type for which output is to be prepared.
</TD></TR></TABLE>
<P>Further names maybe placed in the environment by the
export command and name=value in sh(1) or by the
setenv command if you use csh(1). Arguments may also be placed in the environment at the point of an
exec(2).
</P>
<P>It is risky practice to set name=value pairs that conflict with well-known shell variables. Setting these could cause
surprising behavior in subshells or system(3) commands.
</P>
<P><B>
SEE ALSO
</B></P>
<!-- CODE SNIP //-->
<PRE>
login(1), sh(1), bash(1), csh(1), tcsh(1), exec(2),system(3)
</PRE>
<!-- END CODE SNIP //-->
<P>
Linux, 21 October 1996
</P>
<H3><A NAME="ch05_ 13">
expire.ctl
</A></H3>
<P>expire.ctl—Control file for Usenet article expiration.
</P>
<A NAME="PAGENUM-1122"><P>Page 1122</P></A>
<P><B>
DESCRIPTION
</B></P>
<P>The file /news/lib/expire.ctl is the default control file for the
expire(8) program, which reads it at startup. Blank lines
and lines beginning with a number sign (#) are ignored. All other lines should be in one of two formats.
</P>
<P>The first format specifies how long to keep a record of fully expired articles. This is useful when a newsfeed
intermittently offers older news that is not kept around very long. (The case of very old news is handled by the
_c flag of innd(8).) There should only be one line in this format, which looks like this:
</P>
<!-- CODE SNIP //-->
<PRE>
/remember/:days
</PRE>
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<P>Where days is a floating-point number that specifies the upper limit to remember a Message-ID, even if the article
has already expired. (It does not affect article expirations.)
</P>
<P>Most of the lines in the file will consist of five colon-separated fields, as follows:
</P>
<!-- CODE SNIP //-->
<PRE>
pattern:modflag:keep:default:purge
</PRE>
<!-- END CODE SNIP //-->
<P>The pattern field is comma-separated set of single
wildmat(3)-style patterns that specify the newsgroups to which the rest
of the line applies. Because the file is interpreted in order, the most general patterns should be specified first, and the
most specific patterns should be specified last.
</P>
<P>The modflag field can be used to further limit newsgroups to which the line applies and should be chosen from the
following set:
</P>
<TABLE>
<TR><TD>
M
</TD><TD>
Only moderated groups
</TD></TR><TR><TD>
U
</TD><TD>
Only unmoderated groups
</TD></TR><TR><TD>
A
</TD><TD>
All groups
</TD></TR></TABLE>
<P>The next three fields are used to determine how long an article should be kept. Each field should be either a number of
days (fractions such as 8.5 are allowed) or the word
never. The most common use is to specify the default value for how long
an article should be kept. The first and third
fields—keep and purge—specify the boundaries within which an Expires
header will be honored. They are ignored if an article has no Expires header. The fields are specified in the file as
"lower-bound default upper-bound," and they are explained in this order. Because most articles do not have explicit expiration
dates, however, the second field tends to be the most important one.
</P>
<P>The keep field specifies how many days an article should be kept before it will be removed. No article in the newsgroup
will be removed if it has been filed for less than
keep days, regardless of any expiration date. If this field is the word
never, then an article cannot have been kept for enough days so it will never be expired.
</P>
<P>The default field specifies how long to keep an article if no Expires header is present. If this field is the word
never, then articles without explicit expiration dates will never be expired.
</P>
<P>The purge field specifies the upper bound on how long an article can be kept. No article will be kept longer than the
number of days specified by this field. All articles will be removed after they have been kept for
purge days. If purge is the word never, then the article will never be deleted.
</P>
<P>It is often useful to honor the expiration headers in articles, especially those in moderated groups. To do this, set
keep to zero, default to whatever value you want, and
purge to never. To ignore any Expires header, set all three fields to the same value.
</P>
<P>There must be exactly one line with a pattern of
* and a modflags of A; this matches all groups and is used to set
the expiration default. It should be the first expiration line. For example:
</P>
<!-- CODE //-->
<PRE>
## How long to keep expired history
/remember/:5
## Most things stay for two weeks
:A:14:14:14
## Believe expiration dates in moderated groups, up to six weeks
:M:1:30:42
## Keep local stuff for a long time
foo.*:A:30:30:30
</PRE>
<!-- END CODE //-->
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