Multiline RUN command not working on 0.4.0 about pimod HOT 4 CLOSED

I've created a small example to recreate the behavior, but was not able to reproduce the error:

FROM http://downloads.openwrt.org/releases/18.06.5/targets/brcm2708/bcm2710/openwrt-18.06.5-brcm2708-bcm2710-rpi-3-ext4-factory.img.gz

# test size of the image
RUN sh -c "
    echo hello
    echo world
"

from pimod.

sh of OpenWRT is kind of a special case and does not reproduce the problem clear enough. When using bash -c the error can be reproduces even in OpenWRT.

from pimod.

A central conceptual problem is that printf ' %q' does format the input as bash-escaped string. When supplying these strings to sh, misinterpretations can occur and seem to have happened here.

In the OpenWRT example /bin/sh supports the requested formatting options, but the Debian (vanilla) /bin/sh did not support the format string.

A discussion of the probem can be found here: https://stackoverflow.com/questions/12162010/posix-sh-equivalent-for-bash-s-printf-q

A workaround through reformatting the printf's output is implemented here: https://github.com/mentalisttraceur/esceval/blob/master/sh/esceval.sh

from pimod.

Following the current implementation the guest OS requires /bin/sh to exist and to support the requested format. This additional shell could be circumvented, if there was a chroot option to specify a chdir, because cd inside this additional shell would not be required.

As there is no such option, a custom chroot patch could be useful here.

from pimod.