Published at LXer:

This is something very interesting I found out not too long ago, while hashing out some work with a colleague. As most administrators (or users) who do a fair amount of shell scripting know, the error status or return code (Generally referred to as "errno" in all the man pages) of a process is a fairly common method to use in determining the process flow of a script. The one thing about the value of "errno" (or, literally, the variable "$?" in most shells) is that it's erased with each consecutive process that gets run. Here's how to work around that.

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