5、标准IO和管道PPT作业题

题目：

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答案

1、[root@centos7 ~]# tr [a-z] [A-Z] </etc/issue >/tmp/issue.out
2、[root@centos7 ~]# who | tr [:lower:] [:upper:] > /tmp/who.out
3、[root@centos7 ~]# mail help root <<EOF
Hello,I am root,The system version is centos7, please help to check it,thanks!
CentOS Linux release 7.6.1810 (Core)
EOF
4、[root@centos7 ~]# seq -s+ 100 | bc
5、^M就是\r，是windows的回车
[root@centos7 ~]# cat 1.txt|tr '\r' -d > /tmp/1.txt
或者:set ff=unix
6、[root@centos7 ~]# cat 1.txt|tr '\r' -d > /tmp/1.txt
7、[root@centos7 ~]# echo 'xt.,l 1 jr#!$mn 2 c*/fe 3 uz 4' | tr -dc ' [0-9]'
8、[root@centos7 ~]# echo $PATH | tr : '\n'
9、[root@centos7 ~]# tr [0-9] [a-j] < /etc/passwd >/tmp/1.txt
10、[root@centos7 ~]# cat /etc/centos-release | tr ' ' '\n'