====== Directory Structure ======

How are the linux components organized on disk? 

partitions
/
/usr
/home
swap


Filesystem Hierarchy Standard (FHS) \\ 
https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard

<code>
$ man hier # show complete tree of system folders
</code>

Directories: \\ 
/ - root of the tree \\ 
/bin - binary executable files \\ 
/boot - files used during boot \\ 
/dev - one file for each device, physical and virtual \\ 
/etc - configuration files \\ 
/tmp - temporary files, will be empty at next boot \\ 
/usr - duplicate of whole tree \\ 
/home - one folder for each user \\ 
/root - for the root user, not /home/root \\ 

Directories
  * / - root of the tree
  * /bin - binary executable files
  * /boot - files used during boot
  * /dev - one file for each device, physical and virtual
  * /etc - configuration files
  * /tmp - temporary files, will be empty at next boot
  * /usr - duplicate of whole tree
  * /home - one folder for each user
  * /root - for the root user, not /home/root

See more about the /etc folder \\ 
https://www.linuxnix.com/linux-directory-structure-explainedetc-folder/

Locations for binary executables and scripts.  \\ 
/bin   # in Ubuntu 20, soft link to /usr/bin \\ 
/sbin  # in Ubuntu 20, soft link to /usr/sbin \\ 
/usr/bin   #  \\ 
/usr/sbin  #  \\ 
/usr/local/bin  # put my own scripts here \\ 
/usr/local/sbin  # put my own root scripts here \\ 

sbin - s is for system, for commands that require root privileges
bin - root not required

According to the documentation, /bin and /sbin are for commands that are required before the /usr partition is mounted.  But in Ubuntu 20 on my RacerSwift, they are soft linked to /usr.

The first four - /bin, /sbin, /usr/bin, /usr/sbin - should be populated only by the package manager.  /usr/local/bin and sbin is for files not coming from the package manager.

Where do executables live?

^ Folder              ^ Who populates   ^ Who uses ^   ^
| /bin                | package manager | any user |   |
| /sbin               | package manager | root     |   |
| /usr/bin            | package manager | any user |   |
| /usr/sbin           | package manager | root     |   |
| /usr/local/bin      | any user        | any user |   |
| /usr/local/sbin     | any user        | root     |   |
| /home/me/.local/bin | me              | me       |   |


Notes:
  * /bin vs /sbin - the s stands for system, used by administrators, require root
  * /bin and /sbin - for exes called early in the boot, before /usr is mounted
  * /usr/bin and /usr/sbin - for exes called after /usr is mounted
  * /usr/local - overrides will not be tampered with during package manager update

Special cases
  * /lib
  * /etc/init.d - startup scripts, services
  * Libraries are also executable?
  * What are bin, lib, share?

Where do configuration files live?
  * /etc


====== Directory Structure ======

Filesystem Hierarchy Standard (FHS)

[https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard](https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard)

$ man hier #  show complete list of folders

/ - kernel

/bin - binary executable files

/boot - files used during boot

/dev - hardware devices - not a folder, device and partition names

/etc - configuration files

/tmp - temporary, will be gone at next boot

/usr - duplicate 

/home

/root - for the root user, not /home/root

See more about the /etc folder

[https://www.linuxnix.com/linux-directory-structure-explainedetc-folder/](https://www.linuxnix.com/linux-directory-structure-explainedetc-folder/)

Locations for binary executables and scripts. 

/bin   # in Ubuntu 20, soft link to /usr/bin

/sbin  # in Ubuntu 20, soft link to /usr/sbin

/usr/bin   # 

/usr/sbin  # 

/usr/local/bin  # put my own scripts here

/usr/local/sbin  # put my own root scripts here

sbin - s is for system, for commands that require root privileges

bin - root not required

According to the documentation, /bin and /sbin are for commands that are required before the /usr partition is mounted.  But in Ubuntu 20 on my RacerSwift, they are soft linked to /usr.

The first four - /bin, /sbin, /usr/bin, /usr/sbin - should be populated only by the package manager.  /usr/local/bin and sbin is for files not coming from the package manager.


===== Where do executables live? =====


<table>
  <tr>
   <td><strong>Folder</strong>
   </td>
   <td><strong>Who populates</strong>
   </td>
   <td><strong>Who uses</strong>
   </td>
   <td>
   </td>
  </tr>
  <tr>
   <td>/bin
   </td>
   <td>package manager
   </td>
   <td>any user
   </td>
   <td>
   </td>
  </tr>
  <tr>
   <td>/sbin
   </td>
   <td>package manager
   </td>
   <td>root
   </td>
   <td>
   </td>
  </tr>
  <tr>
   <td>/usr/bin
   </td>
   <td>package manager
   </td>
   <td>any user
   </td>
   <td>
   </td>
  </tr>
  <tr>
   <td>/usr/sbin
   </td>
   <td>package manager
   </td>
   <td>root
   </td>
   <td>
   </td>
  </tr>
  <tr>
   <td>/usr/local/bin
   </td>
   <td>any user
   </td>
   <td>any user
   </td>
   <td>
   </td>
  </tr>
  <tr>
   <td>/usr/local/sbin
   </td>
   <td>any user
   </td>
   <td>root
   </td>
   <td>
   </td>
  </tr>
  <tr>
   <td>/home/me/.local/bin
   </td>
   <td>me
   </td>
   <td>me
   </td>
   <td>
   </td>
  </tr>
</table>


/bin vs /sbin - the s stands for system, used by administrators, require root

/bin and /sbin - for exes called early in the boot, before /usr is mounted

/usr/bin and /usr/sbin - for exes called after /usr is mounted

/usr/local - overrides will not be tampered with during package manager update

Special cases

/lib

/etc/init.d - startup scripts, services

Libraries are also executable?

What are bin, lib, share?

Where do configuration files live?

/etc

Soft links in FHS

/bin -> /usr/bin

/sbin -> /usr/sbin

/lib -> /usr/lib

/lib32 -> /usr/lib32

/lib64 -> /usr/lib64

/libx32 -> /usr/libx32