Re: How to inherent non-zero exit status using pipe? (dash)

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxxx>]

Eric Blake <eblake@xxxxxxxxxx> wrote:
>
> Generally not possible using only POSIX constructs (bash's 'set -o
> pipefail' and '${PIPESTATUS[@]}' are extensions).  But what you _can_ do
> is play with exec to be able to propagate non-zero status from a
> particular portion of a pipeline through a temporary variable or file:
> 
> $ exec 3>&1 # duplicate original stdout
> $ result=$(
>  exec 4>&1 >&3 3>&- # move cmd subst stdout, and restore original
>  { ./main.sh; echo $? >&4 # run command, and record its status
>  } | head -n 3)
> $ echo $? # status from head
> $ echo $result # status from ./main.sh
> $ exec 3>&-

Another way is to use fifos.

Cheers,
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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