[SOLVED] this script's returned value is 120,why??

mirage1993 · 02-23-2014, 02:34 AM

I creat a file and edit it .

Code:

#!/bin/bash

exit 888

then,

Code:

[root@localhost]# ./script.sh 
[root@localhost]# echo $?
120

I want to know why the returned value is not 888,thanks.

Doc CPU · 02-23-2014, 03:47 AM

Hi there,

Quote:

Originally Posted by mirage1993

I creat a file and edit it .

Code:

#!/bin/bash

exit 888

then,

Code:

[root@localhost scripts]# ./script.sh 
[root@localhost scripts]# echo $?
120

I want to know why the returned value is not 888,thanks.

that's because return values are limited to 8 bits for historical reasons. So the given return value of 888 is truncated, the high-order bits are dropped:

Code:

  888 (dec) = 0x0378
 strip high byte and convert back:
  0x78 = 120 (dec)

There you go.

[X] Doc CPU

mirage1993 · 02-23-2014, 03:53 AM

Quote:

Originally Posted by Doc CPU

Code:

  888 (dec) = 0x0378
 strip high byte and convert back:
  0x78 = 120 (dec)

great!!!thank you sooo much!!
@Doc CPU