sha224sum:tldr:a36bf

This command is using the sha224sum utility to check if a file's SHA-224 checksum matches the expected checksum stored in a file.

Let's break down the different components of the command:

• sha224sum: This is the command that computes the SHA-224 checksum of a file.
• --check: This flag tells sha224sum to check the provided checksum against the actual checksum of the file.
• --quiet: This flag suppresses the output of sha224sum and only displays error messages if the checksum does not match.
• ${filename-sha224}: This is a Bash parameter expansion syntax that substitutes the value of the filename-sha224 variable into the command. The actual value should be the path to the file containing the expected SHA-224 checksum.

So, when you execute this command, it will compute the SHA-224 checksum of the file specified by the filename-sha224 variable and compare it against the expected checksum stored in that file. If the two checksums match, it will not display any output. Otherwise, it will display an error message indicating that the checksum does not match.