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scnzzh@ZUBT:~$ echo 'abc123' | tr '[:lower:]' '[:upper:]'
ABC123

scnzzh@ZUBT:~$ echo 'ABC123' | tr '[:upper:]' '[:lower:]'
abc123

 

$ tr '[:upper:]' '[:lower:]' output.txt

 

posted on 2020-11-24 13:26  ZhangZhihuiAAA  阅读(127)  评论(0编辑  收藏  举报