Re: expr exit status

[Eric Blake]

According to Alfred M. Szmidt on 1/19/2010 12:37 AM:
>    What are all the exit statuses I need to check just after expr
>    command?  Is it only need to check 1 or 2 or 3 for fail condition
>    and zero for success ?else pease specify
> 
> You only need to check for non-zero exit codes for failure.

Well, that depends on your definition of failure.  POSIX specifies that
expr has status 0 for successful execution where the output is non-zero
and non-empty, status 1 for successful execution where the output is zero
or empty, status 2 for a successful detection of an invalid expression,
and any status in the range of 3-255 for failed execution.

http://www.opengroup.org/onlinepubs/9699919799/utilities/expr.html

Checking for hard-coded values such as 3 is non-portable, and while it may
work for your particular implementation of expr, it won't necessarily
carry over to other platforms.

-- 
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden

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