exit 和 return

 exit [n]
              Cause the shell to exit with a status of n.  If n is omitted, the exit status is that of the last command executed.  A trap on EXIT is executed before the shell ter-minates.


设置shell 退出时候的状态码,如果n 没有设置,退出状态是上次执行命令



[oracle@june3 dbi]$ cat a1.sh 
exit 10;
[oracle@june3 dbi]$ sh ./a1.sh
[oracle@june3 dbi]$ echo $?
10


[oracle@june3 dbi]$ cat a2.sh
aaa
exit ;
[oracle@june3 dbi]$ sh ./a2.sh
./a2.sh: line 1: aaa: command not found
[oracle@june3 dbi]$ echo $?
127

If neither option is supplied and
              an error occurred or command cannot be found, the exit status is 127

rerurn 函数:
return: can only `return' from a function or sourced script

[oracle@june3 dbi]$ cat a4.sh 
fun() {
ls
return 100
}
fun
[oracle@june3 dbi]$ sh ./a4.sh
1  1.pl  2.pl  3.pl  4.pl  5.pl  a1.sh	a2.sh  a3.sh  a4.sh  aa
[oracle@june3 dbi]$ echo $?
100

[oracle@june3 dbi]$ cat a4.sh 
fun() {
ls
#return 100
}
fun
[oracle@june3 dbi]$ sh ./a4.sh
1  1.pl  2.pl  3.pl  4.pl  5.pl  a1.sh	a2.sh  a3.sh  a4.sh  aa
[oracle@june3 dbi]$ echo $?
0

return 用户返回函数执行的值