Commonly used tests:
-d FILE
FILE exists and is a directory
-e FILE
FILE exists
-f FILE
FILE exists and is a regular file
-h FILE
FILE exists and is a symbolic link (same as -L)
-r FILE
FILE exists and is readable
-s FILE
FILE exists and has a size greater than zero
-w FILE
FILE exists and is writable
-x FILE
FILE exists and is executable
-z STRING
the length of STRING is zero
Example:
if [ -e "$file_name" ] && [ ! -z "$used_var" ]
then
echo "$file_name exists and $used_var is not empty"
fi