The difference between the source in the shell and the direct execution sh

First, we know that there are several ways we execute the shell.

1. Sh/bash uses its built-in command set to execute some commands, such as the following

SH Demo.shbash demo.sh

2. Use./or $SHELLPATH/*.sh the way to execute

./demo.sh/home/vagrant/shell/test.sh

Using the method above, you need to set the method to have execute permission to execute

3. Use source shell.sh or. Shell.sh Method Execution

SOURCE demo.sh. demo.sh

The difference between the three ways

1. File permissions: The second execution method requires the file has X permission to execute, the rest of the methods do not need

2. Variable validity: Using the third method to execute the file, you can increase the validity of the variable, so that it can be in the user under the variable valid

The difference between the source in the shell and the direct execution sh