sd:tldr:6fcf3

This command is using shell scripting to execute two separate commands, echo and sd, and manipulating their outputs using regular expressions.

The command can be broken down into two parts:

1. ${echo 'cargo +nightly watch'}: This part is enclosed in ${}, indicating that the output of this command will be used as input for the next command. It executes the echo command and outputs the string 'cargo +nightly watch'.
2. | sd '(\w+)\s+\+(\w+)\s+(\w+)' 'cmd: $1, channel: $2, subcmd: $3': The | symbol is used to pipe the output of the previous command as input to the next command. In this case, the sd command is used for searching and replacing text using regular expressions.

Now let's break down the arguments passed to the sd command:

• '(\w+)\s+\+(\w+)\s+(\w+)': This is the search pattern written using regular expressions. It consists of three groups surrounded by parentheses:
  • (\w+) matches one or more word characters (letters, numbers, or underscores) and captures it as group 1.
  • \s+ matches one or more whitespace characters.
  • \+ matches a plus symbol.
  • (\w+) matches one or more word characters and captures it as group 2.
  • \s+ matches one or more whitespace characters.
  • (\w+) matches one or more word characters and captures it as group 3.
• 'cmd: $1, channel: $2, subcmd: $3': This is the replacement pattern where $1, $2, and $3 represent the captured groups matched by the regular expression. This pattern will replace the matched text with the formatted string containing the captured values. For example, if the input is 'cargo +nightly watch', it will be replaced with 'cmd: cargo, channel: nightly, subcmd: watch'.

In summary, this command takes the string 'cargo +nightly watch', matches it against the provided regular expression, and replaces it with the formatted string 'cmd: cargo, channel: nightly, subcmd: watch'.