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$ ls /bin $ echo $? $ ls /noexistfile $ echo $? test "$1" = "" && \ { echo usage: echo /root/ex1.sh url exit 1 }
$ f=/etc/passwd $ ls $f >/dev/null 2>&1 && echo Yes || echo No $ f=virus.zip $ clamdscan $f || rm $f $ test -e $f && (clamdscan $f || rm $f) >/dev/null 2>&1