$ find . \( -name '*.tar.gz' -o -name '*.tgz' \) -type f -print0 | xargs -0 zegrep '(SCHILY|LIBARCHIVE)' > bsdtar.txt 2>&1


Matches:
./authors/id/J/JU/JUSTER/ALPM-0.04.tar.gz:Binary file (standard input) matches
./authors/id/J/JU/JUSTER/ALPM-0.05.tar.gz:Binary file (standard input) matches
./authors/id/J/JU/JUSTER/ALPM-0.03.tar.gz:Binary file (standard input) matches
./authors/id/J/JJ/JJORE/B-Utils-0.10.tar.gz:Binary file (standard input) matches
./authors/id/J/JJ/JJORE/Term-HiliteDiff-0.09.tar.gz:Binary file (standard input) matches
./authors/id/J/JJ/JJORE/B-Lint-StrictOO-0.03.tar.gz:Binary file (standard input) matches

Bad gzip wrappers:
gzip: ./authors/id/S/SA/SATOH/List-Enumerator-0.06.tar.gz: unexpected end of file
gzip: ./authors/id/J/JS/JSTENZEL/OpenOffice-PerlPoint-0.03.tgz: invalid compressed data--crc error
gzip: ./authors/id/J/JS/JSTENZEL/OpenOffice-PerlPoint-0.03.tgz: invalid compressed data--length error
gzip: ./authors/id/J/JE/JESSE/RT-OnlineDocs-0.04.tar.gz: unexpected end of file
gzip: ./authors/id/M/MS/MSCHILLI/Sysadm-Install-0.26.tar.gz: unexpected end of file
gzip: ./authors/id/C/CH/CHRMUE/Socket-Class-2.14.tar.gz: unexpected end of file