Important configuration files in RHEL / CentOS

Important Linux Config Files :


For Configuring Ethernet card :-

/etc/hosts (Uses to maintain IP to Hostname to IP convention )

/etc/resolv.conf (DNS Servers for connectivity)

/etc/sysconfig/network (Contains gateway, hostname etc.)

/etc/sysconfig/network-scripts/ifcfg-eth0 (Defualt Network card configuration like IP, MAC address, Subnet mask etc.)


For adduser command :-

/etc/passwd (File contains info about user like UserID, shell, Username, Defualt Directory etc.)

/etc/shadow (File contains mainly encrypted password of a user)

/etc/group (Contains info about groups)

/etc/gshadow (Info about group & related users)

/etc/login.defs (File defines the site-specific configuration for the shadow password suite)

/etc/shells (Contains name of all the types of shells available)


Configuration file for the color ls utility :-

/etc/DIR_COLORS


Configuration file for the grub loader and other related files:-

/etc/grub.conf - Symbolic link of below file

/boot/grub/grub.conf (Grand Unified Boot Loader configuration file)

/boot/vmlinuz-2.6.18-128.el5 (Kernel file, cant be edited just included for your reference)

/boot/initrd-2.6.18-128.el5.img (Initial RAM Disk image)


Configuration files for boot processes :-

/etc/fstab   (descriptive information about the various file systems.)

/etc/inittab   (This file describes how the INIT process should set up the system in a certain run-level.)

/etc/rc.d/rc.sysinit   (starts networking subsystems.)

/etc/rc.d/rc   (This file is responsible for starting/stopping services when the runlevel changes.)

/etc/rc.d/init.d/functions  (This file contains functions to be used by most or all shell scripts in the /etc/init.d directory. Symbolic link - /etc/init.d/functions )

/etc/rc.d/rc*.d/   (contains all startup and kill scripts. Symbolic link - /etc/rc*.d )


Other Configuration files :-

/etc/redhat-release   (printing the banner at login screen.)

/etc/shutdown.allow   (allowing only specified users to shutdown.)

/etc/profile   (System wide environment and startup programs, for login setup)

/etc/inputrc (for terminal settings.)

/etc/profile.d/*.sh (shell scripts needed for login.)

/etc/bashrc   (System wide functions and aliases.)

/etc/modules.conf   (aliases for modules are set.)

/etc/exports   (NFS Server Configuration File, Linux to Linux file transfer)

/etc/vsftpd/vsftpd.conf (FTP Configuration File)

/etc/samba/smb.conf (Samba Server Configuration file, Linux - Windows & Linux - Linux with authentication)

/etc/httpd/conf/httpd.conf (Web server Apache configuration file)

/etc/squid/squid.conf (Proxy Server Configuration file, Bydefualt uses Port No. 3128)

/sbin/shutdown (Used to reboot or shutdown pc)

/sbin/mingetty (Virtual consoles)


Log Files :-

/bin/dmesg (Boot time loaded configurations & Driver details)

/var/log/messages (Real Time Warning, Info messages or logs)

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