linux .和..的区别

[taoge@localhost Desktop]$ cat a.sh

#! /bin/bash

echo "shell script"

export z="f(x) + f(y)"

[taoge@localhost Desktop]$ ./a.sh

shell script

[taoge@localhost Desktop]$ echo $z

[taoge@localhost Desktop]$ . ./a.sh

shell script

[taoge@localhost Desktop]$ echo $z

f(x) + f(y)

[taoge@localhost Desktop]$