How do i use the test command in bash and bash shell scripts?

vaquitasos

See all the options for test in the Man page for test.

The basic syntax is:
test expression

e.g: The expression part is -d /var/log
test -d /var/log

It can also be written as:
[ -d /var/log ]

Some common options for string tests are, see if a string has a value, -n and see if a string is empty (zero value) with -z

The test command can also do tests with integers, check file types, see if a file exists. See the man page for more.