Another test with odd results. command ls with fake args -nehf then echo $? returned 1.

Tried a command that didn't exist (lsd) and returned 127.

Tried real command (ls again) with above args and got 1.

OK me again. I assume were dealing with BASH or my post here is redundant!
The online manual reads:

so a value of 255 would indicate a fatal error. A misuse of args would generate 1, or thats what happens with my testing.

No, it returned correctly.

The value 127 in bash refers to illegal command, i.e., when a command is entered that bash cannot figure out, it returns 127, and it means that your command did not enter the execution phase. The previous command you entered, $ echo $?, was obviously wrong, and bash cannot interpret it, so it returned that value.

Why don't you take a look at Advanced Bash Scripting Guide for further doubts.

I started bash from it, and it is a good starting point. There are pdf files also from www.gnu.org , but you have to search.

BINGO I've cracked it. The exit code 255 means that the exit status is out of range. Return positives from the java instead of negative numbers. Test for this. BASH don't like negative returns.

Exit results must be in the range 0-255 not using 1, 2, 126-165, and 255. These have special meaning.

You should use 3 or 4 for an exit value as 1 is a general error, you could use that but 2 is misuse of shell builtins so use another return value.

SORRY! to UltimaGuy that was your link to the Advanced Bash site that helped me crack it! Credit where credits due!

I'm having the same problem as Andy@DP is having, I'm getting values from $? that don't mean anything (to me that is, no doubt the system knows exactly what they mean).

In the case of my java program, if I run it and it runs into problems, the value of $? is 255, no matter if I return -1, -2 or anything else.

And yes, I have checked the value of $? directly after running the java program.

Read my above post that i entered at the same time you entered yours!

OK, it works now!

To correct a mistake from my part: I stated somewhere that the $? always gave 255 when I executed my java program, this isn't true. Actually, when I return -1, the value of $? is 255, if I return -2, the value of $? is 254 and so on...

So I think I'll use positive integers instead.

Thank you very much to all people who participated in this thread!

Not a problem nephilim.
I like to try and help out whenever I can, I still consider myself to be a newbie in many areas but participating in forums helps broden my knowledge while helping others.

Any how, Andy@DP , you have solved the problem when I browsing through the software forum, but I hope I'll solve it the next time. Let's see ...

So long as one of us solves the problem (or any other member for that matter) then I'll be a happy bunny !

It's probably best to focus on using non-negative numbers are return codes. Conventionally a 0 is success and 1 is error. Some programs may use other numbers greater than 0 for specific error conditions.

The return code an unsigned 8 bit value - which is why you're seeing negative numbers wrap around. If you surf some man pages you'll see that exit codes are non-negative.....at least for man pages that list exit codes. The curl man page lists many in an "EXIT CODES" section. The bash man page talks about exit codes in several different places.