预习作业（一）作业

1、mv file1  ../../dic

2、ln -s /lib64/libc.so  /usr/lib64/lib.so

3、mkdir dic

4、df -h    df -k

5、ls -a /root |tr "\n" " "

6、echo {1..100}|tr " " +|bc  或seq -s + 1 100|bc

7、tr 0-9 a-j 文件

8、tr a-z A-Z </etc/issue >/tmp/issue.out   或cat /etc/issue |tr a-z A-Z | >tmp/issue.out