dongshen7561 2013-08-27 21:24
浏览 40
已采纳

sed相当于PCRE的`。?`

I'm trying to find all instances of aaa and replace it with bbb but preserving the first character preceding the aaa. Here's how I'd do it in PHP with PCRE:

preg_replace('#(.?)aaa#', '\1bbb', 'aaasdfg');

How would I do something like that with sed? Here's my attempt (didn't work):

sed -i.bak -r 's/(.\?)aaa/\1bbb/g' filename.ext

It's a bit of a contrived example. What I'm trying to do is a little more complicated but, long story short, I'm trying to get .? working.

Any ideas?

  • 写回答

1条回答 默认 最新

  • dsfo22654 2013-08-27 21:36
    关注

    Just now I mis-read your question, I thought you want to do .*? with sed. ..

    Ok, now I understand what you mean. In another question from you, I mentioned, for BRE, you have to escape those chars to give them special meaning. But for ERE, you have to escape chars which have special meaning to get literal string.

    You used -r, to let sed use ERE, but you escaped ?, it means, you want to match literal string ?.

    try this:

    sed -i.bak -r 's/(.?)aaa/\1bbb/g' filename.ext
    

    or this:

    sed -i.bak 's/\(.\?\)aaa/\1bbb/g' filename.ext
    

    test:

    default with BRE

    kent$  echo "aaasdf
    xaaasdf"|sed 's/\(.\?\)aaa/\1bbb/'
    bbbsdf
    xbbbsd
    

    with -r, ERE:

    kent$  echo "aaasdf
    xaaasdf"|sed -r 's/(.?)aaa/\1bbb/' 
    bbbsdf
    xbbbsdf
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论

报告相同问题?

悬赏问题

  • ¥15 seatunnel-web使用SQL组件时候后台报错,无法找到表格
  • ¥15 fpga自动售货机数码管(相关搜索:数字时钟)
  • ¥15 用前端向数据库插入数据,通过debug发现数据能走到后端,但是放行之后就会提示错误
  • ¥30 3天&7天&&15天&销量如何统计同一行
  • ¥30 帮我写一段可以读取LD2450数据并计算距离的Arduino代码
  • ¥15 飞机曲面部件如机翼,壁板等具体的孔位模型
  • ¥15 vs2019中数据导出问题
  • ¥20 云服务Linux系统TCP-MSS值修改?
  • ¥20 关于#单片机#的问题:项目:使用模拟iic与ov2640通讯环境:F407问题:读取的ID号总是0xff,自己调了调发现在读从机数据时,SDA线上并未有信号变化(语言-c语言)
  • ¥20 怎么在stm32门禁成品上增加查询记录功能