What is the output of the following command? for token in a b c; do echo -n ${token}; done

anbncn would imply literal 'n' characters are printed, but -n is a flag to echo that suppresses newlines, not a character to output.

The for loop assigns each value (a, b, c) to the variable token in sequence. The echo -n flag suppresses the newline after each output, so all three values are printed consecutively on one line, resulting in abc.

$token$token$token would be the output only if variable expansion were disabled (e.g., inside single quotes), but the shell expands $token to its current value.

{a}{b}{c} is not valid shell output; curly braces have no special meaning in this context and the variable $token is expanded normally.

a b c with spaces would be the output if echo were called once with all tokens as arguments or if newlines separated them, but -n and sequential echo calls produce no spaces.