Chapter 5 - Booting and Editing Files Flashcards
Describe how GRUB Legacy is configured and used
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GRUB Legacy uses the menu’lst or grub.conf configuration file in /boot/grub. This file contains global and per-image options. Use the grub-install program to install the boot loader. when GRUB boots, it presents a menu of OS options that you select using the keyboard arrow keys.
Describe how GRUB 2 is configured and used.
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GRUB 2 uses the /boot/grub/grub.cfg configuration file; however, system administrators are discouraged from editing it directly. Instead, they should rely on automatic configuration scripts and set system-specific defaults in /etc/defaults/grub and the files in /etc/grub.d. As with GRUB Legacy, you can install GRUB 2 using the grub-install program.
Describe the boot process.
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The CPU runs the firmware, the firmware loads and runs a boot loader, the boot loader loads and runs secondary boot loaders (if needed) and the Linux kernel, the Linux kernel loads and runs the initial system program (init) and init starts the rest of the system services via startup scripts that are specific to the startup system (SysV, Upstart, systemd, or something more exotic). BIOS-based computers look for boot loaders in various boot sectors, including the MBR of a hard drive or the boot sector of a disk partition or USB flash drive. EFI-based computers look for boot loaders in files on ESP.
Summarize where to look for boot-time logt information.
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The dmesg command prints out logs from the kernel ring buffer, which holds boot-time and other kernel messages. Other useful information can be found in /var/lof/mesaages and other files in /var/log.
summarize the role of /sbin/init
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The init program is responsible for starting many programs and services on your Linux operating system.
Explain the SysV init system
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The SysV init system uses a default runlevel specified with a line like id:2:initdefault: in the /etc/inittab file. Use commands such as chkconfig, ipdate-rc.d, ntsysv and systemctl to change which services are started when switching tp specific runlevels. Runlevels 0, 1 and 6 are reserved for shutdown, single user mode and rebooting, respectively. Runlevels 3, 4 and 5 are the common user runlevel on Red Hat an dmost other distributions and runlevel 2 is the usual user runlevel on Debian systems.
Describe how to change SysV init runlevels
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The programs init and telinit can be used to change to other runlevels. The shutdown, halt, poweroff and reboot programs are also useful when shutting down, rebotting or switching to single-user mode
Explain the systemd init system
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The systemd init system uses units and targets to control services. The default target is specified by the file /etc/system/default.target and is a link to a target file in the /lib/sysemd/system folder.
Describe how to change systemd init targets
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You use the systemctl program to start and stop services as well as to change the target level of the system.
Describe vi’s three editing modes
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You enter text using insert mode, which supports text entry and deletion. The command and ex modes are used to perform more complex commands or to run outside programs to operate on the text entered or changed in the insert mode.
