ispell:tldr:43338

The command "ispell ${filename}" is used to invoke the ispell utility to spell check a specific file with the given filename.

Here's how the command works:

1. The "$" sign indicates that the following word is a variable.
2. "${filename}" indicates that the variable "filename" is to be substituted with the actual file name you want to spell check.
3. So, if you are running the command "ispell mydocument.txt", the variable "${filename}" will be replaced with "mydocument.txt".
4. The command "ispell" is the actual executable that runs the ispell utility, which is a program used for spell checking.
5. The resulting command, after substituting the variable, becomes "ispell mydocument.txt" which runs the spell check on the file "mydocument.txt".
6. The ispell utility will analyze the specified file for any spelling errors, and if any are found, it will suggest corrections or provide options to ignore or add words to a personal dictionary.

Note: Make sure you have the ispell utility installed on your system before using this command.