tr可以对标准输入的字符进行替换、删除、压缩
1、替换
-bash-3.2# cat 1.txt a b c -bash-3.2# cat 1.txt |tr ‘a-c’ ‘A-C’ A B C
2、删除某个字符
-bash-3.2# cat 1.txt |tr -d ‘c’ a b
3、过虑字符
-bash-3.2# cat 2.txt hello2 shell3 -bash-3.2# cat 2.txt |tr -d -c ‘a-z \n’ hello shell
4、压缩
-bash-3.2# echo “linux and windows”|tr -s ‘ ‘#三个空格 linux and windows
5、简单计算
-bash-3.2# cat 1.txt 1 2 3 4 5 6 -bash-3.2# cat 1.txt |echo $[ $( tr ' ' '+' ) ] 21
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