Tuesday 6 September 2022

Practical - 6:- File System in Linux

 AIM :-  File System  in Linux

Equipment :-   PC with Latest Linux OS

  

Theory :-  Have you wondered why certain programs are located under /bin, or /sbin, or /usr/bin, or /usr/sbin?For example, less command is located under /usr/bin directory. Why not /bin, or /sbin, or /usr/sbin? What is the different between all these directories?In this practical, let us review the Linux filesystem structures and understand the meaning of individual high‐level directories.

 

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 contain binary executables.
  • 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 File

  • 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 filesystems

 

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

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