Part I. System Reference

System Reference

To manage the system effectively, it is crucial to know about its components and how they fit together. This part outlines many important aspects of the system. It covers the boot process, the basic file system layout, the location of crucial system files and file systems, and the basic concepts behind users and groups. Additionally, the X Window System is explained in detail.

Table of Contents

1. Boot Process, Init, and Shutdown
1.1. The Boot Process
1.2. A Detailed Look at the Boot Process
1.2.1. The BIOS
1.2.2. The Boot Loader
1.2.3. The Kernel
1.2.4. The /sbin/init Program
1.3. Running Additional Programs at Boot Time
1.4. SysV Init Runlevels
1.4.1. Runlevels
1.4.2. Runlevel Utilities
1.5. Shutting Down
2. The GRUB Boot Loader
2.1. Boot Loaders and System Architecture
2.2. GRUB
2.2.1. GRUB and the x86 Boot Process
2.2.2. Features of GRUB
2.3. Installing GRUB
2.4. GRUB Terminology
2.4.1. Device Names
2.4.2. File Names and Blocklists
2.4.3. The Root File System and GRUB
2.5. GRUB Interfaces
2.5.1. Interfaces Load Order
2.6. GRUB Commands
2.7. GRUB Menu Configuration File
2.7.1. Configuration File Structure
2.7.2. Configuration File Directives
2.8. Changing Runlevels at Boot Time
2.9. Additional Resources
2.9.1. Installed Documentation
2.9.2. Useful Websites
2.9.3. Related Books
3. File System Structure
3.1. Why Share a Common Structure?
3.2. Overview of File System Hierarchy Standard (FHS)
3.2.1. FHS Organization
3.3. Special File Locations Under Red Hat Enterprise Linux
4. The sysconfig Directory
4.1. Files in the /etc/sysconfig/ Directory
4.1.1. /etc/sysconfig/amd
4.1.2. /etc/sysconfig/apmd
4.1.3. /etc/sysconfig/arpwatch
4.1.4. /etc/sysconfig/authconfig
4.1.5. /etc/sysconfig/autofs
4.1.6. /etc/sysconfig/clock
4.1.7. /etc/sysconfig/desktop
4.1.8. /etc/sysconfig/devlabel
4.1.9. /etc/sysconfig/dhcpd
4.1.10. /etc/sysconfig/exim
4.1.11. /etc/sysconfig/firstboot
4.1.12. /etc/sysconfig/gpm
4.1.13. /etc/sysconfig/harddisks
4.1.14. /etc/sysconfig/hwconf
4.1.15. /etc/sysconfig/i18n
4.1.16. /etc/sysconfig/init
4.1.17. /etc/sysconfig/ip6tables-config
4.1.18. /etc/sysconfig/iptables-config
4.1.19. /etc/sysconfig/irda
4.1.20. /etc/sysconfig/keyboard
4.1.21. /etc/sysconfig/kudzu
4.1.22. /etc/sysconfig/mouse
4.1.23. /etc/sysconfig/named
4.1.24. /etc/sysconfig/netdump
4.1.25. /etc/sysconfig/network
4.1.26. /etc/sysconfig/ntpd
4.1.27. /etc/sysconfig/pcmcia
4.1.28. /etc/sysconfig/radvd
4.1.29. /etc/sysconfig/rawdevices
4.1.30. /etc/sysconfig/samba
4.1.31. /etc/sysconfig/selinux
4.1.32. /etc/sysconfig/sendmail
4.1.33. /etc/sysconfig/spamassassin
4.1.34. /etc/sysconfig/squid
4.1.35. /etc/sysconfig/system-config-securitylevel
4.1.36. /etc/sysconfig/system-config-users
4.1.37. /etc/sysconfig/system-logviewer
4.1.38. /etc/sysconfig/tux
4.1.39. /etc/sysconfig/vncservers
4.1.40. /etc/sysconfig/xinetd
4.2. Directories in the /etc/sysconfig/ Directory
4.3. Additional Resources
4.3.1. Installed Documentation
5. The proc File System
5.1. A Virtual File System
5.1.1. Viewing Virtual Files
5.1.2. Changing Virtual Files
5.2. Top-level Files within the proc File System
5.2.1. /proc/apm
5.2.2. /proc/buddyinfo
5.2.3. /proc/cmdline
5.2.4. /proc/cpuinfo
5.2.5. /proc/crypto
5.2.6. /proc/devices
5.2.7. /proc/dma
5.2.8. /proc/execdomains
5.2.9. /proc/fb
5.2.10. /proc/filesystems
5.2.11. /proc/interrupts
5.2.12. /proc/iomem
5.2.13. /proc/ioports
5.2.14. /proc/kcore
5.2.15. /proc/kmsg
5.2.16. /proc/loadavg
5.2.17. /proc/locks
5.2.18. /proc/mdstat
5.2.19. /proc/meminfo
5.2.20. /proc/misc
5.2.21. /proc/modules
5.2.22. /proc/mounts
5.2.23. /proc/mtrr
5.2.24. /proc/partitions
5.2.25. /proc/pci
5.2.26. /proc/slabinfo
5.2.27. /proc/stat
5.2.28. /proc/swaps
5.2.29. /proc/sysrq-trigger
5.2.30. /proc/uptime
5.2.31. /proc/version
5.3. Directories within /proc/
5.3.1. Process Directories
5.3.2. /proc/bus/
5.3.3. /proc/driver/
5.3.4. /proc/fs
5.3.5. /proc/ide/
5.3.6. /proc/irq/
5.3.7. /proc/net/
5.3.8. /proc/scsi/
5.3.9. /proc/sys/
5.3.10. /proc/sysvipc/
5.3.11. /proc/tty/
5.4. Using the sysctl Command
5.5. Additional Resources
5.5.1. Installed Documentation
5.5.2. Useful Websites
6. Users and Groups
6.1. User and Group Management Tools
6.2. Standard Users
6.3. Standard Groups
6.4. User Private Groups
6.4.1. Group Directories
6.5. Shadow Passwords
6.6. Additional Resources
6.6.1. Installed Documentation
6.6.2. Related Books
7. The X Window System
7.1. The X11R6.8 Release
7.2. Desktop Environments and Window Managers
7.2.1. Desktop Environments
7.2.2. Window Managers
7.3. X Server Configuration Files
7.3.1. xorg.conf
7.4. Fonts
7.4.1. Fontconfig
7.4.2. Core X Font System
7.5. Runlevels and X
7.5.1. Runlevel 3
7.5.2. Runlevel 5
7.6. Additional Resources
7.6.1. Installed Documentation
7.6.2. Useful Websites
7.6.3. Related Books

Note: This documentation is provided {and copyrighted} by Red Hat®, Inc. and is released via the Open Publication License. The copyright holder has added the further requirement that Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder. The CentOS project redistributes these original works (in their unmodified form) as a reference for CentOS-4 because CentOS-4 is built from publicly available, open source SRPMS. The documentation is unmodified to be compliant with upstream distribution policy. Neither CentOS-4 nor the CentOS Project are in any way affiliated with or sponsored by Red Hat®, Inc.