问题
In a shell, what is the difference between?
. executable
and
./executable
In the first one, the dot a shortcut for source right? So is there a difference between ./executable and source executable?
回答1:
is there a difference between ./executable and source executable?
basic difference is,
./foo.sh - foo.sh will be executed in a sub-shell
source foo.sh - foo.sh will be executed in current shell
some example could help to explain the difference:
let's say we have foo.sh:
#!/bin/bash
VAR=100
source it:
$ source foo.sh
$ echo $VAR
100
if you :
./foo.sh
$ echo $VAR
[empty]
another example, bar.sh
#!/bin/bash
echo "hello!"
exit 0
if you execute it like:
$ ./bar.sh
hello
$
but if you source it:
$ source bar.sh
<your terminal exits, because it was executed with current shell>
回答2:
./executable runs an executable which is in the current working directory. (executable is not enough for that if there is no . in your $PATH, and usually there isn't). In this case, executable can be an elf binary, or a script starting with #!/some/interpreter, or anything you can exec (on Linux it's potentially everything, thanks to binfmt module).
. executable sources a shell script into your current shell, whether it has execute permissions or not. No new process is created. In bash, script is searched according to the $PATH variable. Script may set environment variables which will remain set in your shell, define functions and aliases and so on.
回答3:
In the second one you give the path: ./ is the current working directory so it doesn't search in PATH for the executable but in the current directory.
source takes the executable as a parameter and executes it in the current process.
来源：https://stackoverflow.com/questions/14625580/difference-between-executable-and-executable