"apt-mark showmanual" will show you all packages that you have manually installed
"apt-mark showauto" will show you all packages that are automatically installed
"apt-mark showinstall" will show you all the packages that are installed
How is this useful? It tells you what packages are installed in your system.
So you can go "apt-mark showinstall | grep somelibrary" to see if you have a particular library installed that's a dependency.
Atari 130xe in very nice condition, fully tested
$275.00
Atari Power Cube 800XL, 600XL, 65XE, 130XE USB-C Power Supply PSU
$11.25
Atari Atariwriter Word Processor Computer Software Cartridge 400/800/XL/XE
$10.00
Atari 400/800/XL/XE Computer SIO2PC - PC/Mac Disk Drive Emulator Adapter/Device
$15.25
Vintage Atari Megafile 44 External 44MB Drive ST STE Mega
$340.00
SoftSide Magazine FlipBooks Issues 39, 40, 43, 44 Atari 8-Bit Editions 400/800
$34.98
$3200.00
Atari SIO2SD (Lotharek v1.3) Disk Drive Emulator - Atari 400/800/XL/XE Computers
$59.95
A8picoCart Atari 130 / 65 XE 800 / 1200 XL XEGS multicart UnoCart clone game
$32.95
Atari 1050 US Doubler upgrade kit
$35.00