for z in *.zip; do unzip -t $z; done | grep unzip

End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of US_basics.zip or
        US_basics.zip.zip, and cannot find US_basics.zip.ZIP, period.
unzip:  cannot find zipfile directory in one of US_basics.zip or
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of VICE_sw.zip or
unzip:  cannot find zipfile directory in one of VICE_sw.zip or
        VICE_sw.zip.zip, and cannot find VICE_sw.zip.ZIP, period.

for z in *.zip; do unzip $z; done

find /где-ищем -iname "*.zip" -type f -execdir unzip {} \;

find /где-ищем -iname "*.zip" -type f -execdir unzip -t {} \; | grep unzip