Using the && operator in an if statement
So to make your expression work, changing && for -a will do the trick.
It is correct like this:
if [ -f $VAR1 ] && [ -f $VAR2 ] && [ -f $VAR3 ] then ....or like
if [[ -f $VAR1 && -f $VAR2 && -f $VAR3 ]] then ....or even
if [ -f $VAR1 -a -f $VAR2 -a -f $VAR3 ] then ....You can find further details in this question bash : Multiple Unary operators in if statement and some references given there like What is the difference between test, [ and [[ ?.