CMake：如何在参数中用双引号调用 execute_process？ a.k.a。使用 CMake 中的查找来计算匹配字符串的行数

Question

我想调用命令find from within a execute_process。

find命令的格式为：

find [/v] [/c] [/n] [/i] [/off[line]] "<String>" [[<Drive>:][<Path>]<FileName>[...]]

因此，字符串必须用双引号引起来。但是，如果在 cmake 中我这样做：

execute_process(COMMAND <firstCommandPipingSomethingToFind> 
                COMMAND find "<myString>" /c
                OUTPUT_VARIABLE MY_COUNT
                OUTPUT_STRIP_TRAILING_WHITESPACE)

我收到一个错误 FIND: Parameter format not correct。
如果我用 \ 转义双引号，我会得到一个错误 Access denied - \.
同样使用双转义 \ 或双引号 "" 也无济于事。

所以我的问题是：
有没有办法在调用 execute_process 时转义双引号，以便 find 正确接收其参数？

我可以使用 findstr, which doesn't need the double quotes; however it doesn't provide a counting feature. I could use find by calling find /v /c ""，但同样，我需要双引号！我想在cmake之外计算输出行数，并将结果直接存储在MY_COUNT变量中。

注意：我正在使用 CMake 3.4.1

要重现该问题，您可以使用以下代码，其中 cmake -E echo 用于将字符串提供给 findstr 和 find:

#This works
execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND findstr ell OUTPUT_VARIABLE DUMMY)
message (STATUS "0) DUMMY=${DUMMY}")

#All of the following don't work
set(MyCommand "find \"ell\" /c")
execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND "${MyCommand}" OUTPUT_VARIABLE DUMMY)
message (STATUS MyCommand=${MyCommand})
message (STATUS "1) DUMMY=${DUMMY}")

execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND ${MyCommand} OUTPUT_VARIABLE DUMMY)
message (STATUS "2) DUMMY=${DUMMY}")

execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND MyCommand OUTPUT_VARIABLE DUMMY)
message (STATUS "3) DUMMY=${DUMMY}")

execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND "find \"ell\" /c" OUTPUT_VARIABLE DUMMY)
message (STATUS "4) DUMMY=${DUMMY}")

输出：

0) DUMMY=hello

MyCommand=find "ell" /c
1) DUMMY=
2) DUMMY=
3) DUMMY=
4) DUMMY=

我也试过了

set(MyArgument "\"ell\" /c")
message (STATUS MyArgument=${MyArgument})
execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND find "${MyArgument}" OUTPUT_VARIABLE DUMMY)
message (STATUS "1) DUMMY=${DUMMY}")

execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND find ${MyArgument} OUTPUT_VARIABLE DUMMY)
message (STATUS "2) DUMMY=${DUMMY}")

set(MyArgument "\"ell\"")
message (STATUS MyArgument=${MyArgument})
execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND find "${MyArgument}" /c OUTPUT_VARIABLE DUMMY)
message (STATUS "1) DUMMY=${DUMMY}")

execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND find ${MyArgument} /c OUTPUT_VARIABLE DUMMY)
message (STATUS "2) DUMMY=${DUMMY}")

输出：

MyArgument="ell" /c
File not found - \ELL\

1) DUMMY=
File not found - \ELL\

2) DUMMY=
MyArgument="ell"
Access denied - \

1) DUMMY=
Access denied - \

2) DUMMY=
CMake Error at CMakeRules.cmake:404 (execute_process):
  execute_process given COMMAND argument with no value.
Call Stack (most recent call first):
  CMakeLists.txt:24 (include)

如果删除 /c 选项，问题仍然存在。

这个：

execute_process(COMMAND ${CMAKE_COMMAND} -E echo hello COMMAND find \"ell\" OUTPUT_VARIABLE DUMMY)
message (STATUS "DUMMY=${DUMMY}")

输出这个：

Access denied - \

DUMMY=

按照 Tsyvarev 的建议检索有效传递给命令行的字符串，这：

execute_process(COMMAND cmd /c echo \"ell\")
execute_process(COMMAND cmd /c echo "ell")
execute_process(COMMAND cmd /c echo ""ell"")

输出这个：

\"ell\"

ell

"" ell\"\"

第三条命令有警告：

Argument not separated from preceding token by whitespace.
This warning is for project developers.  Use -Wno-dev to suppress it.

Answer 1

According to CMake developers,
由于 CreateProcess API 和non-standard 方式 find 解析参数。

虽然可以通过创建临时批处理脚本间接调用。

我计算 Windows 中程序输出的字符串出现次数的问题已通过以下方式解决：

file(WRITE ${CMAKE_BINARY_DIR}/countLines.bat [[@find /v /c "" %1]])
execute_process(COMMAND <firstCommandPipingSomethingToFind> COMMAND findstr <regular expression> COMMAND countLines.bat WORKING_DIRECTORY ${CMAKE_BINARY_DIR} OUTPUT_VARIABLE N_MATCHES OUTPUT_STRIP_TRAILING_WHITESPACE)
message(STATUS "N_MATCHES=${N_MATCHES}")
file(REMOVE ${CMAKE_BINARY_DIR}/countLines.bat)

中间的findstr的优点是支持正则表达式。 find 只用于 count matching lines.

find前面的@是为了防止脚本中的命令调用在输出变量中结束。

CMake：如何在参数中用双引号调用 execute_process？ a.k.a。使用 CMake 中的查找来计算匹配字符串的行数

CMake: How to call execute_process with a double quote in the argument? a.k.a. Using find from CMake to count lines matching a string

windows

cmake

find

findstr