examples/script/file_tests.sh
if [ $# != 1 ]
then
   echo "Usage $0 FILE"
   exit 1
fi

if [ ! -e $1 ]
then
    echo "$1 does NOT exist"
    exit
fi

if [ -f $1 ]
then
   echo $1 if a file
   exit
fi

if [ -d $1 ]
then
   echo $1 if a directory
   exit
fi

$ ./examples/script/file_tests.sh 
Usage ./examples/script/file_tests.sh FILE

$ ./examples/script/file_tests.sh abc
abc does NOT exist

$ ./examples/script/file_tests.sh .
. if a directory

$ ./examples/script/file_tests.sh examples/script/file_tests.sh 
examples/script/file_tests.sh if a file

The spaces inside the square brackets are significant.

-e    thing exists
-f    thing is a file
-d    thing is a directory
-L    thing is a symbolic link
-s    thing is not empty
...
-r    thing is readable by current user
-w    thing is writable by current user
-x    thing is executable by current user