Main Directories
bin - for binary executables. Common commands are found here - ps, ls, ping, grep, cp etc. These are basic programs for proper OS operation.
sbin - same but more about system maintainance like lptables, reboot, fdisk, ifconfig etc.
etc - configurations for user accounts and programs.
var - files that expected to grow and change contantly. Contains /var/logs for surprise-surprise… wait for it… logs. Wow! 😯
tmp - contains temprory files, which are deleted on system reboot.
home - main user directory.
boot - boot loaded files are here.
dev - device files, that represent hardware connected to the system.
lib - shared libraries to use by different programs.
usr - This directory contains user-related programs, libraries, and data files, including system utilities, games, documentation, and other user-related files.
☢️ Can’t be moved from the root: /etc, /lib, /sbin (from some tests on the Internet). ?? ChatGPT says
bin,boot,dev,sbin.
Disks and Devices
⚠️ If PATA and SATA are both used, PATA are listed first
Shortcuts
Ctrl+A, Ctrl+E - move the cursor to the start or end of the line.
Ctrl+R, Ctrl+S - search bash history (backwards and forwards). Terminate with Ctrl+G.
Environment Variables
LD_PRELOAD affects DLL and Set-UID progs.
References
[1] About Linux run levels