懂C語言的人， 沒有不知道函式的， 下面我們來看看linux shell script中的函式， 其實也很簡單：

[[email protected] learn_shell]$ ls
a.sh
[[email protected] learn_shell]$ cat a.sh 
#! /bin/bash

fun()
{
	echo "calling fun"
}

echo "begin ---"
fun   # call fun
echo "end ---"
[[email protected] learn_shell]$ 
[[email protected]
 
 learn_shell]$ 
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ ./a.sh 
begin ---
calling fun
end ---
[[email protected] learn_shell]$ 

     再看：

[[email protected] learn_shell]$ ls
a.sh
[[email protected]
 
 learn_shell]$ cat a.sh 
#! /bin/bash

fun()
{
	echo $1
}

echo "begin ---"
fun  # call fun
echo "end ---"
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ 
[[email protected]ost learn_shell]$ ./a.sh good
begin ---

end ---
[[email protected]
 
 learn_shell]$ 

     那行， 我們來傳一下引數：

[[email protected] learn_shell]$ ls
a.sh
[[email protected] learn_shell]$ cat a.sh 
#! /bin/bash

fun()
{
	echo $0
	echo $1
}

echo "begin ---"
fun "$1"  # call fun
echo "end ---"
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ ./a.sh 
begin ---
./a.sh

end ---
[[email protected] learn_shell]$ ./a.sh good
begin ---
./a.sh
good
end ---

       可見， 引數傳遞成功。

       最後， 我們來看看return, 注意return 0表示成功：

[[email protected] learn_shell]$ ls
a.sh
[[email protected] learn_shell]$ cat a.sh 
#! /bin/bash

fun()
{
	return 0
}

echo "begin ---"

if fun
then
	echo good
else
	echo bad
fi

echo "end ---"
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ 
[[email protected] learn_shell]$ ./a.sh 
begin ---
good
end ---
[[email protected] learn_shell]$ 

        linux shell script函式就是這麼簡單， 你想任性一點， 那也可以。