Index: chapter.sgml
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RCS file: /home/dcvs/doc/en_US.ISO8859-1/books/handbook/config/chapter.sgml,v
retrieving revision 1.250
diff -u -r1.250 chapter.sgml
--- chapter.sgml 31 Jan 2012 14:14:59 -0000 1.250
+++ chapter.sgml 10 Feb 2012 01:15:29 -0000
@@ -475,22 +475,21 @@
The cron utility uses two different
types of configuration files, the system crontab and user crontabs. The
only difference between these two formats is the sixth field. In the
- system crontab, the sixth field is the name of a user for the command
- to run as. This gives the system crontab the ability to run commands
- as any user. In a user crontab, the sixth field is the command to run,
+ system crontab, cron will run the command as this user.
+ In a user crontab, the sixth field is the command to run,
and all commands run as the user who created the crontab; this is an
important security feature.User crontabs allow individual users to schedule tasks without the
- need for root privileges. Commands in a user's crontab run with the
- permissions of the user who owns the crontab.
+ need for root privileges. Commands in a user's crontab run with the
+ permissions of the user who owns the crontab.
The root user can have a user crontab just like
- any other user. This one is different from
- /etc/crontab (the system crontab). Because of the
- system crontab, there is usually no need to create a user crontab
- for root.
+ any other user. root's crontab is
+ distinct from /etc/crontab (the system crontab).
+ Because of the system crontab, there is usually no need to
+ create a user crontab for root.
Let us take a look at the /etc/crontab file
@@ -547,11 +546,9 @@
day of the week. All these fields must be numeric values, and follow
the twenty-four hour clock. The who field is special,
and only exists in the /etc/crontab file.
- This field specifies which user the command should be run as.
- When a user installs his or her crontab file, they
- will not have this option. Finally, the command option is listed.
- This is the last field, so naturally it should designate the command
- to be executed.
+ The command will be run as the user named in this
+ field. Finally, the last field is the command to be
+ executed.
@@ -584,13 +581,13 @@
Installing a Crontab
- You must not use the procedure described here to
- edit/install the system crontab. Simply use your favorite
- editor: the cron utility will notice that the file
- has changed and immediately begin using the updated version.
- See
-
- this FAQ entry for more information.
+ Do not use the procedure described here to
+ edit and install the system crontab. Simply use your favorite
+ editor: the cron utility will notice that the file
+ has changed and immediately begin using the updated version.
+ See
+ this FAQ entry
+ for more information.To install a freshly written user
@@ -613,8 +610,7 @@
without the use of a template, the crontab -e
option is available. This will invoke the selected editor
with an empty file. When the file is saved, it will be
- automatically installed by the crontab command.
-
+ automatically installed by the crontab command.
If you later want to remove your user crontab
completely, use crontab with the
@@ -636,7 +632,7 @@
- Using rc under &os;
+ Using rc Under &os;In 2002 &os; integrated the NetBSD
rc.d system for system initialization.
@@ -1108,7 +1104,7 @@
The status of the link (status)
- is active, i.e. the carrier is detected.
+ is active, i.e., the carrier is detected.
For dc1, we see
status: no carrier. This is normal when
an Ethernet cable is not plugged into the card.
@@ -1664,7 +1660,7 @@
seeing processes started from other users, the following tunables can
be set in sysctl.conf:
- # Do not log fatal signal exits (e.g. sig 11)
+ # Do not log fatal signal exits (e.g., sig 11)
kern.logsigexit=0
# Prevent users from seeing information about processes that
@@ -1674,7 +1670,7 @@
- Tuning with sysctl
+ Tuning with sysctlsysctl
@@ -1944,7 +1940,7 @@
out of space and the update to fail.
- More Details about Soft Updates
+ More Details About Soft UpdatesSoft Updates
@@ -2070,7 +2066,7 @@
fsck though.)
The advantage is that meta-data operations are nearly as
- fast as asynchronous updates (i.e. faster than with
+ fast as asynchronous updates (i.e., faster than with
logging, which has to write the
meta-data twice). The disadvantages are the complexity of
the code (implying a higher risk for bugs in an area that
@@ -2200,7 +2196,7 @@
heavily loaded web server environment. For such environments, it
is recommended to increase this value to 1024 or
higher. The service daemon may itself limit the listen queue size
- (e.g. &man.sendmail.8;, or Apache) but
+ (e.g., &man.sendmail.8;, or Apache) but
will often have a directive in its configuration file to adjust
the queue size. Large listen queues also do a better job of
avoiding Denial of Service (DoS) attacks.
@@ -2390,15 +2386,35 @@
of the Handbook.
- Swap on a New Hard Drive
+ Swap on a New or Existing Hard Drive
+
+ The best way to add swap space, and the way that gives the best
+ performance, is to add a new swap partition on an existing or new hard
+ drive. Setting up partitions and hard drives is explained in
+ .
+ discusses partition layouts and swap partition size considerations.
+
+ Use &man.swapon.8; to add a swap partition to the system. For example:
+
+ &prompt.root; swapon/dev/ada1s1p2
+
+
+ It is possible to use any partition not currently mounted, even
+ if it already contains data. Using &man.swapon.8; on a partition that
+ contains data will overwrite and destroy that data.
+ Make sure that the partition to be added as swap
+ is really the intended partition before running
+ swapon.
+
+
+ To automatically add this swap partition on boot,
+ add an entry to /etc/fstab for the
+ partition:
+
+ /dev/ada1s1p1 none swap sw 0 0
- The best way to add swap, of course, is to use this as an
- excuse to add another hard drive. You can always use another
- hard drive, after all. If you can do this, go reread the
- discussion of swap space
- in
- of the Handbook for some suggestions on how to best
- arrange your swap.
+ &man.fstab.5; explains the entries in
+ /etc/fstab.
@@ -2739,7 +2755,7 @@
An ACPI-compliant system has various
components. The BIOS and chipset vendors
- provide various fixed tables (e.g., FADT)
+ provide various fixed tables (e.g., FADT)
in memory that specify things like the APIC
map (used for SMP), config registers, and
simple configuration values. Additionally, a table of bytecode
@@ -2878,7 +2894,7 @@
on Linux, it is likely a &os; driver problem and narrowing down
which driver causes the problems will help us fix the problem.
Note that the ACPI maintainers do not
- usually maintain other drivers (e.g sound,
+ usually maintain other drivers (e.g., sound,
ATA, etc.) so any work done on tracking
down a driver problem should probably eventually be posted
to the &a.current.name; list and mailed to the driver
@@ -2898,7 +2914,7 @@
- System Hangs (temporary or permanent)
+ System Hangs (Temporary or Permanent)Most system hangs are a result of lost interrupts or an
interrupt storm. Chipsets have a lot of problems based on how
@@ -3058,7 +3074,7 @@
how to fix them:
- _OS dependencies
+ _OS DependenciesSome AML assumes the world consists of
various &windows; versions. You can tell &os; to claim it is
@@ -3070,7 +3086,7 @@
- Missing Return statements
+ Missing Return StatementsSome methods do not explicitly return a value as the
standard requires. While ACPI-CA
@@ -3112,8 +3128,7 @@
- Getting Debugging Output From
- ACPI
+ Getting Debugging Output from ACPIACPI