1. sed -n '1~2p' /etc/passwd
2.sed -n '2~10p' /etc/passwd | sed 's/bin/linux/g'
3.sed -n '$p' /etc/passwd
4.sed -r 's/^#|[ ]'//g' /etc/fstab
5.sed -n '1,3w /root/file.txt' /etc/passwd
6.rpm -ivh ntp-0.7.12X86_64.rpm
rpm -e --nodeps ntp-0.7.12X86_64.rpm
rpm -uvh ntp-0.7.12X86_64.rpm
7.
rpm -qR openssl.x86.rpm
rpm -ql openssl.x86.rpm
rpm --test openssl.x86.rpm
rpm -qi openssl.x86.rpm
rpm -qf /usr/lib/libssl.so.6
8.
mount -t auto /dev/sr0 /mnt
9.yum list installed redis