Really old sh -- pipefail

[Richard Laager]

On 2026-09-09 17:13, Hal Murray wrote:
> 
>> I just tested in dash, which is a minimal sh that does not support
>> pipefail. That code works as written and does not work without the ().
> 
> Thanks.  What do you mean by "does not work"?

dash immediately dies.

$ cat test1.dash
if set -o pipefail 2>/dev/null
then
   echo PIPEFAIL supported
else
   echo PIPEFAIL not supported
fi
echo HERE
$ dash test1.dash
$ cat test2.dash
if (set -o pipefail) 2>/dev/null
then
   echo PIPEFAIL supported
else
   echo PIPEFAIL not supported
fi
echo HERE
$ dash test2.dash
PIPEFAIL not supported
HERE
$

Note that "dash test1.dash" did not echo "HERE".

> As I see it, there are 2 cases: either the sh supports pipefail or it
> doesn't.
> 
> If it does support pipefail then a simple "set -o pipefail" works as
> expected.
> If it doesn't support pipefail, then that gets an error message and
> pipefail doesn't get turned on.

and the shell dies:

$ cat test.dash
set -o pipefail
echo HERE
$ dash test.dash
test.dash: 1: set: Illegal option -o pipefail

-- 
Richard