bash is the debian / ubuntu and other major linux distribution command line interface, all system and application commands are executed through the shell.
for ex ./myscript.sh launches a script.
You can pipe/ manipulate in/output in bash , for example using sed, awk or grep or inbuilt options see for example:
https://www.thegeekstuff.com/2010/07/bash-string-manipulation/
You also can automate almost any system task using shell scripts

May read this
https://github.com/awesome-lists/awesome-bash