zstdless:tldr:b28d4

The command "zstdless ${filename-zst}" is a shell command that uses the zstdless utility to decompress and display the contents of a file that has been compressed using the Zstandard compression algorithm.

Let's break down the command into its components:

1. "zstdless": This is the name of the utility being invoked. It is a tool used to decompress and view the compressed contents of a file.

2. "${filename-zst}": This is a variable substitution used to specify the name of the file to be decompressed. The variable "filename" is substituted with the actual filename, and the "-zst" part indicates that the file has a ".zst" extension, which is the common extension used for Zstandard compressed files.

Overall, the command takes the filename variable, substitutes it with the given filename, and runs the zstdless utility to decompress and display the contents of the specified file.