Note: Question does not duplicate Ignoring specific errors in a shell script .

Suppose it is needed to capture the leading characters of a encoded representation of a file.

In shell (tested in Bash), it is easy to use the following form:

encoded="$(< file base64 | head -c16)"

The statement functions desired, except under certain alterations to the environment.

Consider the following:

set -o errexit -o pipefail
shopt -s inherit_errexit
encoded="$(< file base64 | head -c16)"

The final line would cause termination of a script, because of the non-zero return status (141) given by base64, unhappy with closed pipe. The return status is propagated to the pipe and then to the invoking shell.

The undesired effect requires a workaround, such as follows:

set -o errexit -o pipefail
shopt -s inherit_errexit
encoded="$((< file base64 || :) | head -c16)"

The : has the same effect as would have the keyword true, to evaluate as a non-error.

However, this approach leads to a further unwanted effect.

The following shows a variation with a different error:

set -o errexit -o pipefail
shopt -s inherit_errexit
encoded="$((< /not/a/real/file base64 || :) | head -c16)"
echo $?

The printed code is zero. Now, a true error has been masked.

The most obvious solution, as follows, is rather verbose

set -o errexit -o pipefail
shopt -s inherit_errexit
encoded="$((< /not/a/real/file base64 || [ $? == 141 ]) | head -c16)"
echo $?

Is a more compact form available? Is any environment alteration available such that statements masks only the particular status code, without the explicit inline expression?