tr替换

tr替换： tr 替换字符：被替换的字符与替换的字符数必须是相等的 用法：tr 旧字符 新字符

cat > a.txt <<EOF root:1:0:bin bin:2:200:bash jim:10:300:bash tom:102:10:bash bin:2:200:bash EOF

cat a.txt | tr 20 89 将cat a.txt中的结果中的20替换成89 root:1:9:bin bin:8:899:bash jim:19:399:bash tom:198:19:bash bin:8:899:bash

cat a.txt | tr 'a-z' 'A-Z' 在替换的时候是一一对应的替换 ROOT:1:0:BIN BIN:2:200:BASH JIM:10:300:BASH TOM:102:10:BASH BIN:2:200:BASH

cat a.txt | tr 0-4 5-9 root:6:5:bin bin:7:755:bash jim:65:855:bash tom:657:65:bash bin:7:755:bash

\n 换行符 cat a.txt | tr "\n" "+" 将换行符换成+号 root:1:0:bin+bin:2:200:bash+jim:10:300:bash+tom:102:10:bash+bin:2:200:bash+

cat a.txt | tr -s "o0" 用-s把连续重复的字符替换成一个字符 rot:1:0:bin bin:2:20:bash jim:10:30:bash tom:102:10:bash bin:2:20:bash

echo >> a.txt 在a.txt文件中追加空白行,请执行3次

cat a.txt | tr -s "\n" 去掉空白行