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这种命令是什么：command-name > &!file-name

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这种命令是什么：command-name > &!file-name

我在某处遇到了具有以下格式的终端命令：

command-name > &! file-name

该怎么办呢？

答案1

据我所知唯一> &!有效的 shell 是(t)csh。来自man tcsh：

   > name
   >! name
   >& name
   >&! name
           The  file  name  is used as standard output.  If the file does
           not exist then it is created; if the file exists, it is  trun‐
           cated, its previous contents being lost.

           If the shell variable noclobber is set, then the file must not
           exist or be a character special  file  (e.g.,  a  terminal  or
           `/dev/null') or an error results.  This helps prevent acciden‐
           tal destruction of files.  In this case the `!' forms  can  be
           used  to suppress this check.  If notempty is given in noclob‐
           ber, `>' is  allowed  on  empty  files;  if  ask  is  set,  an
           interacive confirmation is presented, rather than an error.

           The  forms  involving `&' route the diagnostic output into the
           specified file as  well  as  the  standard  output.   name  is
           expanded in the same way as `<' input filenames are.

例如，如果file存在但nofile不存在，则

$ csh -c 'set noclobber; ls -l file nofile > & outfile'
$ cat outfile
ls: cannot access 'nofile': No such file or directory
-rw-r--r-- 1 steeldriver steeldriver 70 Nov 22 15:10 file

然后

$ csh -c 'set noclobber; ls -l file nofile > & outfile'
outfile: File exists.

但添加!

$ csh -c 'set noclobber; ls -l file nofile > &! outfile'

成功。因此 的!含义与 中 的含义有些相似vi。

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