Index: chapter.sgml =================================================================== 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 <literal>rc</literal> 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 <command>sysctl</command> sysctl @@ -1944,7 +1940,7 @@ out of space and the update to fail. - More Details about Soft Updates + More Details About Soft Updates Soft 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 Dependencies Some 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 Statements Some methods do not explicitly return a value as the standard requires. While ACPI-CA @@ -3112,8 +3128,7 @@ - Getting Debugging Output From - <acronym>ACPI</acronym> + Getting Debugging Output from <acronym>ACPI</acronym> ACPI