tr:tldr:4eb0b

The command tr -d '${input_characters}' < ${filename} is using the tr command along with some arguments and input/output redirection to perform a specific operation.

Here's an explanation of each component:

• tr is a command-line utility in UNIX-like operating systems that translates or deletes characters. It can be used to modify or manipulate text streams.
• -d is an option or argument for the tr command which specifies the action to delete characters.
• '${input_characters}' is a placeholder for the specific characters you want to delete. It should be replaced with the actual characters you want to remove. The single quotes (' ') are used to prevent any variable expansions by the shell.
• < ${filename} is an input redirection operator that takes the contents of a file (specified by the ${filename} variable) and feeds it as input to the tr command. The file contents will be used as the text stream to perform the character deletion.

To summarize, this command deletes the specified characters (identified by ${input_characters}) from the contents of the file specified by ${filename}. The modified text stream is then printed to the standard output.