kate:tldr:85c4c

This command is used to open the contents of a file in the text editor called Kate.

Here's a breakdown of the command:

• cat is a command-line utility in Unix-like systems that is used to concatenate and display the contents of one or more files. In this case, it is used to read the contents of a file.

• ${filename} represents a variable that holds the name of the file you want to open in Kate. The syntax ${...} is used to access the value of a variable in many scripting languages and shells like Bash or Python.

• | is a pipe symbol that connects the output of one command (in this case, cat) to the input of another command (in this case, kate) through a pipeline. It allows the output of one command to be used as the input for another command.

• kate is the command to execute the text editor Kate.

• --stdin is an argument or option passed to Kate to indicate that it should read the contents from the standard input stream (which is being provided by the output of cat through the pipe).

So, combining these together, the command cat ${filename} | kate --stdin reads the contents of the file named by the variable ${filename} using cat, then passes that output to kate to open it in the editor.