Tuesday, July 14, 2015

Linux Configuration Files and their explanations

System wide environment and startup script program.
The /dev/MAKEDEV file is a script written by the system administrator that creates local only device files or links such as device files for a non-standard device driver.
Where the user's name is matched to a nickname for e-mail.
The configuration for the BOOTP server daemon.

Lists commands and times to run them for the cron deamon.
The configuration file for the DHCP server daemon.
File for RARP mapping from hardware addresses to IP addresses. See the man page ethers(5).
The file describing exported filesystems for NFS services.
The floppy disk parameter table. Describes the formats of different floppy disks. Used by setfdprm.
Can be used to set the filesystem probe order when filesystems are mounted with the auto option. The nodev parameter is specified for filesystems that are not really locally mounted systems such as proc, devpts, and nfs systems.
Lists the filesystems mounted automatically at startup by the mount -a command (in /etc/rc or equivalent startup file).
Similar to /etc/passwd but for groups rather than users.
May contain passwords that let a user join a group.
Used to hold the group password and group administrator password information for shadow passwords.
Specifies how host names are resolved.
List hosts for name lookup use that are locally required.
Shows the host name of this host. Used for support of older programs since the hostname is stored in the /etc/sysconfig/network file.
Configuration file for init, controls startup run levels, determines scripts to start with.
Sets up the services that run under the inetd daemon.
Output by getty before the login prompt. Description or welcoming message.
Output for network logins with LINUX version
Configuration file for ld.so, the run time linker.
Configuration file for LILO.
Limits users resources when a system has shadow passwords installed.
In Debian the system time zone is determined by this link.
Sets user login features on systems with shadow passwords.
Configures the logrotate program used for managing logfiles.
The configuration file for file types. Contains the descriptions of various file formats for the file command.
The message of the day, automatically output by a successful login.
A list of currently mounted file systems. Setup by boot scripts and updated by the mount command.
Used for domain name servers.
Lists names and addresses of your own and other networks, used by the route command.
If this file exists, non-root logins are disabled. Typically it is created when the system is shutting down.
Name service switch configuration file.
The user database with fields giving the username, real name, home directory, encrypted password and other information about each user.
A configuration file for printers.
/etc/profile, /etc/cshlogin,
Files executed at login or startup time by the Bourne or C shells. These allow the system administrator to set global defaults for all users.
Describes DARPA internet protocols available from the TCP/IP subsystem. Maps protocol ID numbers to protocol names.
/etc/rc or /etc/rc.d or /etc/rc?.d
Scripts or directories of scripts to run at startup or when changing run level.
Contains files used to control run level 0. Usually these files are softlink files.
Contains files to control run level 1. Scripts beginning with an S are for start, K for kill.
Init runs this when it starts.
Configures the name resolver, specifying the address of your name server and your domain name.
Identifies secure terminals from which root is allowed to log in.
Lists the network services that the system supports.
Shadow password file on systems with shadow password software installed. Shadow passwords move the encrypted password files from /etc/passwd to /etc/shadow which can only be read by root.
Systems with shadow passwords may have this file.
Lists trusted shells. The chsh command allows users to change their login shell to shells listed only in this file.
Can be used by administrator to set the editor environment variable to some editor that is friendly to new users.
A list of users with special privileges along with the commands they can execute.
The configuration file for setting up Samba services.
Used to configure the auto mount daemon.
Used to configure the system clock to Universal or local time and set some other clock parameters.
Controls the system font settings.
This file is used to set some terminal characteristics and environment variables.
Used to configure the keyboard.
This file is used to configure the mouse.
Defines a network interface.
Used to configure pcmcia network cards.
Sets up dynamic routing policies.
Configures static routes on a network.
Used for backup tape device configuration.
The configuration file for the X server.
Configuration file for the syslogd daemon.
The terminal capability database. Describes by what "escape sequences" various terminals can be controlled. See terminfo, termcap, curs_termcap man pages.
Details for terminal I/O.
This file is used to impose special access restrictions on users.
User aliases, path modifier, and functions.
Users environment stuff and startup programs.
User actions to be done at logout.
When this file exists in the user's home directory, it will prevent check for mail, printing of the last login time, and the message of the day when the user logs in.
Contains keybindings and other bits.
Has networking and environment info.
Information about the processor such as its type, make and performance.
A list of devices configured into the currently running kernel.
Shows which DMA channels are being used at the moment.
Filesystems that are configured into the kernel. The file used to detect filesystems if the /etc/filesystems does not exist.
Shows which I/O ports are in use at the moment.
Shows which interrupts are in use and how many of each there have been.
An image of the physical memory of the system.
Messages output by the kernel. These are also routed to syslog.
Symbol table for the kernel.
The load average of the system.
Information about memory usage, both physical and swap.
Which kernel modules are currently loaded.
Contains information on filesystems currently mounted, similar to /etc/mtab
Contains status information about network protocols.
A symbolic link to the process directory of the program that is looking at /proc. When 2 process look at proc, they get different links.
Various statistics about the system such as the number of page faults since the system was booted.
The time the system has been up.
The kernel version.
FVWM-M4 defines. Contains networking, Xwindows, other setup info.
Time zone datafiles are stored here on the Debian system
Used by finger to tell when a user was last logged in.
Binary info on users that have been logged on. The last command uses this info.
Contains information about users currently logged in. Who and w commands use this file.
Used for domain name server. Placed here optionally, but this is the normal location.
Files used by domain name server. Placed here optionally, but this is the normal location.
Used to store information about failed logins. This file must be first created to activate it.
Contains information about the last time a login was done on the system. Works with lastb(1).
The normal system mail log file.
The main system message log file.
System tracking of user logins. Check this file periodically.
Where mailboxes are usually stored.

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