command used by the shell (1)--"and (&&)", "OR (| | ）”，“：”，"."

Commands common to the shell:

1, and list with or list:

1), and List (&&):

Executes the next command when the previous command executes successfully.

When there is an execution failure, reverse the "failure code" directly.

Use:

Statement 1 && Statement 2 && statement 3 && .....

2), or list (| | ）：

In contrast to &&, the next statement executes after the current statement fails.

Use:

Statement 1 | | Statement 2 | | Statement 3 | | 。。。。。

3), the above two can be combined, for logical processing.

4), the command can be combined into blocks execution.

Statement 1 && {Statement 2 | | Statement 3}

2, ":" Command:

1), in fact, ":" is an empty command. Used to simplify conditional logic, equivalent to "true"

Like what:

While://Make an infinite loop.

2), for variable settings:

Like what:

: ${var:=value}//may be treated as a command when $var does not have ":".

3, "." Command:

1), used to indicate execution within the current shell, does not create a child shell.

Equivalent to the "source" command.

command used by the shell (1)--"and (&&)", "OR (| | ）”，“：”，"."