Thanks. I found myself wanting to use eval today, because I was trying to build up a complicated docker-compose command depending on certain flags. First I tried doing

docker-compose \
  -f x.yml \
if [ -n $BLA ]; then
  -f y.yml \
fi
 ;

But this didn’t work, because bash doesn’t work like an html templating language. So I built up the string and then tried to execute the comnand in backticks, but that swallowed the stdout from my docker containers:

 CMD="docker compose"
 CMD="${CMD} -f x.yml"
 if [ -n $BLA ]; then
  CMD="${CMD} -f y.yml"
 fi
 `$CMD`

Then I googledexec .. that looked a bit too hardcore — I didn’t need to replace the parent process. Then I googled eval and that looked like what I wanted, which did indeed work:

 CMD="docker compose"
 CMD="${CMD} -f x.yml"
 if [ -n $BLA ]; then
  CMD="${CMD} -f y.yml"
 fi
 eval "$CMD"

But your article also came up in the results, and although I have no intention of allowing user input here, you inspired me to see if I could do this without eval and sure I can!

 ARGS="-f x.yml"
 if [ -n $BLA ]; then
  ARGS="${ARGS} -f y.yml"
 fi
docker-compose $ARGS

Thanks for inspiring me to do better!