organising files into folders
what happens if you redirect output to a file being used as input?
sort -n lengths.txt > lengths.txt
using >> to append output to a file
pipelines and understanding what text flows through each step of the pipeline
extensions don't mean anything – .txt is just a convention
combining cut sort uniq wc
checking quality of data, removing damaged files
Most files’ names are something.extension. The extension isn’t required, and doesn’t guarantee anything, but is normally used to indicate the type of data in the file.
command >> [file] appends a command’s output to a file.
[first] | [second] is a pipeline: the output of the first command is used as the input to the second.
The best way to use the shell is to use pipes to combine simple single-purpose programs (filters).