Operating System · Redhat / CEntOS / Oracle Linux · Ubuntu

UNIX – Directory Structure and Explanations

 

1. / – Root:-

  •  Every single file and directory starts from the root directory.
  •  Only root user has write privilege under this directory.
  •  Please note that /root is root user’s home directory, which is not same as /.

2. /bin – User Binaries:-

  • Contains binary executables.
  • Common Linux commands you need to use in single-user modes are located under this directory.
  • Commands used by all the users of the system are located here.
  • For example: ps, ls, ping, grep, cp.

3. /sbin – System Binaries:-

  • Just like /bin, /sbin also contains binary executable.
  • But, the Linux commands located under this directory are used  typically,by system administrator, for system maintenance purpose.

For example: iptables, reboot, fdisk, ifconfig, swapon

4. /etc – Configuration Files

  • Contains configuration files required by all programs.
  • This also contains startup and shutdown shell scripts used to start/stop  individual programs.

For example: /etc/resolv.conf, /etc/logrotate.conf

5. /dev – Device Files:-

  • Contains device files.
  • These include terminal devices, usb, or any device attached to the system.

For example: /dev/tty1, /dev/usbmon0

6. /proc – Process Information:-

  • Contains information about system process.
  • This is a pseudo filesystem contains information about running process. For example: /proc/{pid} directory contains information  about the process with that particular pid.
  • This is a virtual filesystem with text information about system resources. For example: /proc/uptime

7. /var – Variable Files:-

  • Var stands for variable files.
  • Content of the files that are expected to grow can be found under this directory.
  • This includes — system log files (/var/log); packages and database files (/var/lib); emails (/var/mail); print queues (/var/spool); lock files (/var/lock); temp files needed across reboots (/var/tmp);

8. /tmp – Temporary Files:-

  • Directory that contains temporary files created by system and users.
  • Files under this directory are deleted when system is rebooted .

9. /usr – User Programs:-

  •  Contains binaries, libraries, documentation, and source-code for second  level programs.
  •  /usr/bin contains binary files for user programs. If you can’t find a user binary under /bin, look under /usr/bin. For example: at, awk, cc, less, scp
  •  /usr/sbin contains binary files for system administrators. If you can’t find a system binary under /sbin, look under /usr/sbin. For example: atd, cron, sshd, useradd, userdel
  • /usr/lib contains libraries for /usr/bin and /usr/sbin
  • /usr/local contains users programs that you install from source. For example, when you install apache from source, it goes under /usr/local/apache2

10. /home – Home Directories:-

  • Home directories for all users to store their personal files.
  • For example: /home/john, /home/nikita

11. /boot – Boot Loader Files:-

  • Contains boot loader related files.
  • Kernel initrd, vmlinux, grub files are located under /boot
  • For example: initrd.img-2.6.32-24-generic, vmlinuz-2.6.32-24-generic

12. /lib – System Libraries :-

  •     Contains library files that supports the binaries located under /bin and /sbin
  •      Library filenames are either ld* or lib*.so.*
  •     For example: ld-2.11.1.so, libncurses.so.5.7

13. /opt – Optional add-on Applications:-

  • opt stands for optional.
  • Contains add-on applications from individual vendors
  • Add-on applications should be installed under either /opt/ or /opt/ sub-directory.

 14. /mnt – Mount Directory:-

  •    Temporary mount directory where sysadmins can mount file systems.

 15. /media – Removable Media Devices:-

  • Temporary mount directory for removable devices.
  • For examples, /media/cdrom for CD-ROM; /media/floppy for floppy drives; /media/cdrecorder for CD writer

 16. /srv – Service Data :-

  • srv stands for service.
  •  For example, /srv/cvs contains CVS related data
  • Contains server specific services related data.

 

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