在Windows中的ruby中，执行cmd提示命令“ move”会给出错误“命令的语法不正确。”

Question

in ruby in windows, executing the cmd prompt command 'move' gives error "The syntax of the command is incorrect."

But it works outside of ruby

C:\rubytest>echo asdf>c:\techprogs\azzz.azz

C:\rubytest>del c:\techprogs\azzz.azz

C:\rubytest>echo asdf>c:\techprogs\azzz.azz

C:\rubytest>move /y c:\techprogs\azzz.azz c:\techprogs\autorun.bat
        1 file(s) moved.

C:\rubytest>move /y c:\techprogs\azzz.azz c:\techprogs\autorun.bat
The system cannot find the file specified.

C:\rubytest>

All of that above is fine and expected.

Notice I never get an error that says "The syntax of the command is incorrect."

Then try in ruby

I have a simple file with one line

C:\rubytest>type syntaxcommandincorrect.rb
`move /y c:\techprogs\azzz.azz c:\techprogs\autorun.bat`

C:\rubytest>

But it gives that error about the syntax

C:\rubytest>del c:\techprogs\azzz.azz

C:\rubytest>ruby syntaxcommandincorrect.rb
The syntax of the command is incorrect.

C:\rubytest>echo asdf>c:\techprogs\azzz.azz

C:\rubytest>ruby syntaxcommandincorrect.rb
The syntax of the command is incorrect.

C:\rubytest>

Answer 1

The problem here is probably the backslashes which have significant meaning inside of interpolated Ruby strings, double-quoted but also backtick-style shell commands.

As such your command is being interpreted as:

move /y c:^Iechprogs^Gzzz.azz c:^Iechprogs^Gutorun.bat

Where ^I is "\\t" which is a tab character, and ^G is "\\a" which is a bell character .

Instead:

`move /y c:\\techprogs\\azzz.azz c:\\techprogs\\autorun.bat`

Now remember that Ruby has a very comprehensive library of functions you can use to address this directly. Don't treat it like a fancy shell scripting language:

require 'fileutils'

FileUtils.mv('c:\techprogs\azzz.azz', 'c:\techprogs\autorun.bat', force: true)

Where here I'm using single quotes to avoid the double backslashes and force: true is the equivalent of /y . This uses FileUtils.mv , part of a whole package of useful file and directory manipulation utilities.

As a plus you also get proper exceptions if something goes wrong, or an error code if the move failed.

Added by barlop

Confirming the above. Double backslash fixes it, and i see via doing puts `echo copy /yc:\\techprogs...` what happens with single backslash, I see the t of techprogs removed, as c:\\techprogs became c:<ascii-9>echprogs. And \\autorun became <ascii-7>utorun

C:\rubytest>cmdoutoutwithoutinitbat.rb | xxd
0000000: 6162 6364 6566 670d 0a63 6f70 7920 2f79  abcdefg..copy /y
0000010: 2063 3a09 6563 6870 726f 6773 0775 746f   c:.echprogs.uto
0000020: 7275 6e2e 6261 7420 633a 0965 6368 7072  run.bat c:.echpr
0000030: 6f67 7307 7a7a 7a2e 617a 7a0d 0a61 6263  ogs.zzz.azz..abc
0000040: 6465 6667 0d0a 6d6f 7665 202f 7920 633a  defg..move /y c:
0000050: 0965 6368 7072 6f67 7307 7a7a 7a2e 617a  .echprogs.zzz.az
0000060: 7a20 633a 0965 6368 7072 6f67 7307 7574  z c:.echprogs.ut
0000070: 6f72 756e 2e62 6174 0d0a                 orun.bat..

C:\rubytest>