xe:tldr:0e0a8

The given command is a combination of two separate commands connected by a pipe(|):

1. echo -e 'a\nb': This command uses the echo command with the -e option to interpret escape sequences. It prints two lines, "a" and "b", each on a separate line.

2. xe -N${2} -s 'echo $2 $1': This command uses a custom command or script called xe. The -N${2} argument means that it takes an additional argument (let's assume it's the number 2) and assigns it to the variable N within the script. The -s option specifies that the following string should be executed as a script.

The script passed to xe as an argument is 'echo $2 $1'. It uses shell variables $1 and $2, where $1 refers to the first argument (a) and $2 refers to the second argument (b). Therefore, when the script is executed, it will output b a since it echoes the second variable followed by the first variable.

In summary, this command prints "a" and "b" using echo, and then xe takes the second argument and executes a script that echoes the second argument followed by the first argument.