Basic knowledge of shell scripts

First line:

the first line of #!/bin/bash-e indicates that the following script is processed with bash syntax. Because most Linux defaults to bash, you can not write this line.
The parameter-e indicates that once an error occurs, the current shell is exited.

A variety of common judgments:

-D: Determine if directory-
z: Determine whether a variable has a value, for example:-Z "$JAVA _home"-
F: Determine whether it is a file-
L: Determine if it is a symbolic link-r: To determine whether it is readable-
s: Present and not 0 true
-W: Determines whether to write-
x: Determines whether an existing object can be executed
. : Negative sign of test condition