sed 匹配行内出现n次

ynchnluiti

原帖由 dreamone503 于 2008-11-13 13:45 发表
诸位大侠, 给解释下含义被?
没用过tb  Tb阿, 而且另起一行的:b;d是什么意思阿?

sed -n '/aaa/{s//&/3;tb;s//&/2;Tb;p}
:b;d' urfile

man sed

       : label
              Label for b and t commands.
       t label
              If a s/// has done a successful substitution since the last input line was read and since the last t or T command, then branch to label; if
              label is omitted, branch to end of script.
       T label
              If no s/// has done a successful substitution since the last input line was read and since the last t or T command, then branch  to  label;
              if label is omitted, branch to end of script.

:b;定义标签b
tb;是上一次s///成功则跳到b;否则继续执行。
Tb;跟tb相反，替换不成功跳转

yezhulin1982

学习了！

dreamone503

领教领教,谢谢诸位

这样运行可以, sed -n '/aaa/{s//&/3;tb;s//&/2;Tb;p};:b;d' urfile

不知为何下边句子中 :b;d 要单起一行?
sed -n '/aaa/{s//&/3;tb;s//&/2;Tb;p}
:b;d' urfile

ynchnluiti

原帖由 dreamone503 于 2008-11-14 11:45 发表
领教领教,谢谢诸位

这样运行可以, sed -n '/aaa/{s//&/3;tb;s//&/2;Tb;p};:b;d' urfile

不知为何下边句子中 :b;d 要单起一行?
sed -n '/aaa/{s//&/3;tb;s//&/2;Tb;p}
:b;d' urfile

都可以，一个是分号，一个是回车。都可以分割命令。