请帮忙解释下 echo <<123 789

xz00xz

$ echo <<123 789
> 567
> 123
789
为啥echo对<<123加入的内容无视呢？多谢先！

davistar

search heredoc

xz00xz

2l的意思是在本地文档中查找？
好像没发现什么变化，请再详细些，俺是菜鸟。。多谢！

ly5066113

原帖由 xz00xz 于 2008-3-11 10:55 发表
2l的意思是在本地文档中查找？
好像没发现什么变化，请再详细些，俺是菜鸟。。多谢！

......

google here document

nuclearxin

Here Documents
       This  type of redirection instructs the shell to read input from the current source
       until a line containing only word (with no trailing blanks) is seen.   All  of  the
       lines read up to that point are then used as the standard input for a command.

       The format of here-documents is:

              <<[-]word
                      here-document
              delimiter

       No  parameter  expansion,  command  substitution, arithmetic expansion, or pathname
       expansion is performed on word.  If any characters in word are quoted,  the  delim-
       iter is the result of quote removal on word, and the lines in the here-document are
       not expanded.  If word is unquoted, all lines of the here-document are subjected to
       parameter expansion, command substitution, and arithmetic expansion.  In the latter
       case, the character sequence \<newline> is ignored, and \ must be used to quote the
       characters \, $, and `.

       If  the  redirection  operator is <<-, then all leading tab characters are stripped
       from input lines and the line containing  delimiter.   This  allows  here-documents
       within shell scripts to be indented in a natural fashion.

   Here Strings
       A variant of here documents, the format is:

              <<<word

       The word is expanded and supplied to the command on its standard input.

nuclearxin

但是似乎 还是没有解释 楼主的意思
123 为啥不能称为 word delimiter

xz00xz

意思是echo不能用standard input?

nuclearxin

呵呵我理解错了   echo   他 echo出了 here doc    然后 有echo  出 后面的 789

waker

因为牛只能挤出来牛奶，不管你喂的是香蕉还是香肠

xz00xz

欧，谢谢各位~
反正就是echo不能用here doc。。。