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Nature40 / pimod

Reconfigure Raspberry Pi images with an easy, Docker-like configuration file
GNU General Public License v3.0
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Multiline RUN command not working on 0.4.0 #37

Closed adur1990 closed 2 years ago

adur1990 commented 2 years ago

In Pimod version 0.2.2, I used to use the following code:

RUN bash -c "
  cd somewhere
  do something here
  more commands here
"

But with Pimod 0.4.0, which was uploaded a few days ago, this fails with the following error:

### RUN bash -c
  cd somewhere
  do something here
  more commands here

/bin/bash: $n: command not found
### Error: "bash" returned 127, cleaning up...
jonashoechst commented 2 years ago

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
"
jonashoechst commented 2 years ago

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.

jonashoechst commented 2 years ago

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

jonashoechst commented 2 years ago

https://github.com/Nature40/pimod/blob/12e8ae4c62328bdb51c76739b0c85fda2162a602/stages/30-chroot.sh#L72-L73

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.