Fedora Linux

time , shifts the local time by one hour through the spring and summer months. In most jurisdictions in North America, the local time jumps from 2:00 a.m. to 3:00 a.m. during the spring time change and from 3:00 a.m. to 2:00 a.m. during the autumn time change. The spring time change has been held on the first Sunday in April, but that will change (experimentally) to the second Sunday in March in 2007. The fall time change has been held on the last Sunday in October, which will change to the first Sunday in November in 2007. If the changes do not result in significant energy savings, governments may revert to the traditional dates.

This means that there is no 2:30 a.m. local time on the day of the spring time change, and that 1:30 a.m. local time happens twice on the day of the fall time change.

crond was written to take this issue into account. Jobs scheduled to run between 2:00 and 3:00 a.m. during the spring time change will execute as soon as the time change occurs, and jobs scheduled to run between 1:00 and 2:00 a.m. during the autumn time change will be executed only once.

6.4.3.2. ...using an editor other than vi to edit the crontab?

The environment variable EDITOR can be used to specify a different editor, such as emacs , joe , or mcedit . You can set this variable temporarily by assigning a value on the same command line as the crontab command:

$ EDITOR= joe crontab -e

It may be useful to edit your ~/.bash_profile and add this line to permanently specify a different editor:

export EDITOR= mcedit

6.4.3.3. ...loading the crontab from a file?

When executed without any arguments, the crontab command will read the crontab configuration from the standard input. You can use this feature to load the configuration from a file:

$ crontab < /tmp/newcrontab

To see the current crontab configuration, use the -l option:

$ crontab -l
# Backup ~chris/oreilly/ to bluesky:~chris/backup/ as a tar archive
30 0,12 * * * /usr/local/bin/bluesky-backup-oreilly
# Update the local rawhide repository
0 5 * * * /usr/local/bin/rawhide-rsync
Putting these features together, you can create a simple script to edit a crontab configuration:
#!/bin/bash
# addtmpclean :: add a crontab entry to clean ~/tmp daily
(crontab -l ; echo '30 4 * * * rm -f ~/tmp/*')|crontab

6.4.4. Where Can I Learn More?

? The manpages for cron , crontab(1), crontab(5), anacron, and anacrontab

Chapter 7. Network Services

Fedora, like most Linux and Unix systems, makes no distinction between server and client systems. In fact, many Fedora systems participate in both roles, both serving and consuming information.

It should come as no surprise, then, that Fedora Core ships with a full complement of software for serving everything from web pages and email to files and printer connections. These server packages are based on open standards and interoperate with other platforms, so you can use a Fedora system to serve Windows, Mac, Linux, or Unix clients.

Most Fedora servers are extensively configurable. Configuration information is stored in text files, but the format of the text files varies, and the information in those files goes by different names directives , statements , parameters , or options depending on the program. Red Hat has developed convenient graphical configuration tools for most of the server configuration files.

Services are programs that constantly run in the background. Services can start automatically when the system starts, but not all services are configured this way by default (see Lab 4.6, 'Managing and Configuring Services').

It also might be necessary to adjust your firewall or SELinux configuration to use the services discussed in this chapter (see Chapter 8 for more information).

7.1. Configuring Samba to Share Files with Windows Systems

Fedora can be configured to use Samba to serve files and printers to a wide range of Windows systems using Microsoft-compatible protocols.

Samba can be configured to work with a wide range of Windows versions and to serve resources in many different ways. This lab is focused on sharing files and printers with Windows XP systems in a small workgroup, which is a common scenario in home and small-business networks.