systemd-run:tldr:7a79e

This command is using three commands together, connected by the pipe (|) operator, which allows the output of one command to be passed as input to the next command.

1. ${command1}: The first command is represented by ${command1}. It could be any valid command or script that produces output when executed. The exact command is not specified here.

2. systemd-run --pipe ${command2}: This is the second command in the pipeline. It uses the systemd-run command with the --pipe option. systemd-run is a command in the systemd system and service manager suite, used for running commands in transient or background processes. The --pipe option tells systemd-run to create a pipe and connect the standard output of the command ${command2} to that pipe.

3. ${command3}: This is the final command in the pipeline. Again, like ${command1}, it represents any valid command or script. The output from the systemd-run command (connected via the pipe) will be passed as input to this third command.

In summary, this command runs ${command1} as the first step. The output from ${command1} is then piped to systemd-run --pipe ${command2}. The output from ${command2} is then passed as input to ${command3}.