#introif [ -n $1 ]    then        echo 666    else        echo 555fiexit;Actually I do want to echo 555 while I don't want to do anything in the first block, what should I do? I noticed that I can't just remove echo 666.
What if I don't want to do anything in a if-then block but something in its else block?
shell
Just using no-op:if [ -n $1 ]; then  :else  echo 555fiexitor invert the logic:if [ -z $1 ]; then  echo 555fiexit