Exploring Important files, their locations and their usage

Linux is a complex system which requires a more complex and efficient way to start, stop, maintain and reboot a system unlike Windows. There is a well defined configuration files, binaries, man pages, info files, etc. for every process in Linux.

  • /boot/vmlinuz : The Linux Kernel file.
  • /dev/hda : Device file for the first IDE HDD (Hard Disk Drive)
  • /dev/hdc : Device file for the IDE Cdrom, commonly
  • /dev/null : A pseudo device, that don’t exist. Sometime garbage output is redirected to /dev/null, so that it gets lost, forever.
  • /etc/bashrc : Contains system defaults and aliases used by bash shell.
  • /etc/crontab : A shell script to run specified commands on a predefined time Interval.
  • /etc/exports : Information of the file system available on network.
  • /etc/fstab : Information of Disk Drive and their mount point.
  • /etc/group : Information of Security Group.
  • /etc/grub.conf : grub bootloader configuration file.
  • /etc/init.d : Service startup Script.
  • /etc/lilo.conf : lilo bootloader configuration file.
  • /etc/hosts : Information of Ip addresses and corresponding host names.
  • /etc/hosts.allow : List of hosts allowed to access services on the local machine.
  • /etc/host.deny : List of hosts denied to access services on the local machine.
  • /etc/inittab : INIT process and their interaction at various run level.
  • /etc/issue : Allows to edit the pre-login message.
  • /etc/modules.conf : Configuration files for system modules.
  • /etc/motd : motd stands for Message Of The Day, The Message users gets upon login.
  • /etc/mtab : Currently mounted blocks information.
  • /etc/passwd : Contains password of system users in a shadow file, a security implementation.
  • /etc/printcap : Printer Information
  • /etc/profile : Bash shell defaults
  • /etc/profile.d : Application script, executed after login.
  • /etc/rc.d : Information about run level specific script.
  • /etc/rc.d/init.d : Run Level Initialisation Script.
  • /etc/resolv.conf : Domain Name Servers (DNS) being used by System.
  • /etc/securetty : Terminal List, where root login is possible.
  • /etc/skel : Script that populates new user home directory.
  • /etc/termcap : An ASCII file that defines the behaviour of Terminal, console and printers.
  • /etc/X11 : Configuration files of X-window System.
  • /usr/bin : Normal user executable commands.
  • /usr/bin/X11 : Binaries of X windows System.
  • /usr/include : Contains include files used by ‘c‘ program.
  • /usr/share : Shared directories of man files, info files, etc.
  • /usr/lib : Library files which are required during program compilation.
  • /usr/sbin : Commands for Super User, for System Administration.
  • /proc/cpuinfo : CPU Information
  • /proc/filesystems : File-system Information being used currently.
  • /proc/interrupts : Information about the current interrupts being utilised currently.
  • /proc/ioports : Contains all the Input/Output addresses used by devices on the server.
  • /proc/meminfo : Memory Usages Information.
  • /proc/modules : Currently using kernel module.
  • /proc/mount : Mounted File-system Information.
  • /proc/stat : Detailed Statistics of the current System.
  • /proc/swaps : Swap File Information.
  • /version : Linux Version Information.
  • /var/log/lastlog : log of last boot process.
  • /var/log/messages : log of messages produced by syslog daemon at boot.
  • /var/log/wtmp : list login time and duration of each user on the system currently.


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