sed:tldr:d36c1

This command is using the sed command in Linux/Unix to search and replace the word "apple" with "mango" in a file specified by the ${filename} variable.

Let's break down the command:

• sed: This is the command for stream editor, which is used for text manipulation.
• -i: This option tells sed to perform an in-place edit, meaning it will modify the file directly rather than displaying the output on the terminal.
• 's/apple/mango/g': This is the search and replace expression. The s/ indicates a substitution operation, and apple is the word being searched for. It will be replaced with mango. The g flag at the end means it will replace all occurrences of "apple", not just the first one it finds.
• ${filename}: This is a variable that holds the name of the file where the search and replace operation will be performed. You can replace ${filename} with the actual file name or provide it as an argument when executing the command.

Overall, this command will search for every occurrence of the word "apple" in the specified file and replace it with "mango", effectively performing a global search and replace operation.