In an SSH shell command, “–” (double dash) is used as a command line option separator. It separates options from positional parameters and is used to indicate that no further options are to be parsed.
For example, consider the following command:
ssh user@host -- ls -l
Here, the “–” is used to separate the options passed to the “ls” command from any options that may be passed to the “ssh” command. This way, the “ls” command will only receive the options “-l”, and any further options that may follow the “–” will be treated as positional parameters and not as options to the “ssh” command.
In this way, the double dash can be used to avoid ambiguity in commands with multiple options.