Linux

Why does Debian have both apt and apt-get commands for package management?

apt is newer and offers a more high-level, user-friendly interface than apt-get.

apt also has a few noteworthy features that apt-get does not, like automatically removing obsolete package versions with apt upgrade or recommending suggested package installs to fix dependency issues.

see https://aws.amazon.com/compare/the-difference-between-apt-and-apt-get/

How do sh and bash differ? How might #!/bin/bash vs. #!/bin/sh shebangs differ in their effects on subsequent code?

sh (Shell Command Language or Bourne Shell) is defined in the POSIX standard and is the foundation for multiple derived implementations, including bash. bash is a superset of sh that includes other commands like history and other features like process substitution. Scripts that use these features may* fail when told to run with sh.

*In Linux distributions such as Ubuntu or Linux Mint, however, #!/bin/sh is a symlink to #!/bin/dash (like bash but faster), so in practice there may be little to no difference in how the two shebang lines affect script behavior.