Red Hat LINUX 7.2 - OFFICIAL LINUX CUSTOMIZATION GUIDE Guida di Installazione Scaricare il pdf (Pagina 74)

74 Chapter 3. Boot Process, Init, and Shutdown

• In the graphical GRUB boot loader screen, select the Red Hat Linux boot label and press [e] to

edit it.

• Arrow down to the kernel line and press [e] to edit it.

• At the prompt, type single and press [Enter].

• You will be returned to the GRUB screen with the kernel information. Press the [b] key to boot the

system into single user mode.

A very bare system will boot, and you will have a command shell from which you can ﬁx things.

If this does not work, you will need to boot by typing linux init=/bin/bash at the LILO

boot: prompt. This places you at a shell prompt; note that no ﬁlesystems other than the root ﬁlesystem

are mounted, and the root ﬁlesystem is mounted in read-only mode. To mount it in read-write mode

(to allow editing of a broken /etc/inittab, for example) do:

mount -n /proc

mount -o rw,remount /

3.4.1. Initscript Utilities

The chkconfig utility in /sbin provides a simple command-line tool for maintaining the

/etc/rc.d/init.d directory hierarchy. It relieves system administrators from having to directly

manipulate the numerous symbolic links in the directories under /etc/rc.d.

In addition, there is ntsysv that provides a text-based interface, which you may ﬁnd easier to use than

chkconfig’s command-line interface.

If you prefer a graphical interface, use the serviceconf program.

All of these utilities must be run as root.

Please refer to the chapter titled Controlling Access to Services in Ofﬁcial Red Hat Linux Customiza-

tion Guide for more information regarding these tools.

3.5. Running Programs at Boot Time

The ﬁle /etc/rc.d/rc.local script is run by init at boot time, after all other initialization is

complete, and whenever you change runlevels. You can add additional initialization commands here.

For instance, you may want to start up additional daemons or initialize a printer.

In addition, if you require serial port setup, you can create and edit /etc/rc.serial, and it will

be executed automatically at boot time. This script can run a number of setserial commands to

specially conﬁgure the system’s serial ports. See the setserial man page for more information.

3.6. Shutting Down

To shut down Red Hat Linux, issue the shutdown command. You can read the shutdown man page

for complete details, but the two most common uses are:

/sbin/shutdown -h now

/sbin/shutdown -r now

You must run shutdown as root. After shutting everything down, the -h option will halt the machine,

and the -r option will reboot.

Although the reboot and halt commands are now able to invoke shutdown if run while the system

is in runlevels 1-5, it is a bad habit to get into, as not all Linux-like operating systems have this feature.

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Red Hat LINUX 7.2 - OFFICIAL LINUX CUSTOMIZATION GUIDE Guida di Installazione Pagina 74