cmake：如何在自定义命令中包含文字双引号？ [英] cmake: How to include literal double-quote in custom command?

问题描述

我正在尝试创建一个自定义命令，它运行一些环境变量，如LDFLAGS，如果它的值需要引用，如果它包含空格：

I'm trying to create a custom command that runs with some environment variables, such as LDFLAGS, whose value needs to be quoted if it contains spaces:

LDFLAGS="-Lmydir -Lmyotherdir"

在cmake自定义命令中包含此参数，由于cmake的转义规则。这是我到目前为止所尝试的：

I cannot find a way to include this argument in a cmake custom command, due to cmake's escaping rules. Here's what I've tried so far:

COMMAND LDFLAGS="-Ldir -Ldir2" echo blah VERBATIM)

产生LDFLAGS = \-Ldir -Ldir2 \echo blah

yields "LDFLAGS=\"-Ldir -Ldir2\"" echo blah

COMMAND LDFLAGS=\"-Ldir -Ldir2\" echo blah VERBATIM)

产生 LDFLAGS = \-Ldir -Ldir2\echo blah

似乎我得到整个字符串引用，或者转义的引号在作为命令的一部分使用时不会解析。

It seems I either get the whole string quoted, or the escaped quotes don't resolve when used as part of the command.

希望包含文字双引号的方法，或者作为一个更好的方法来为命令设置环境变量。请注意，我仍然在cmake 2.8，所以我没有新的env命令可用在3.2。提前感谢！

Would appreciate either a way to include the literal double-quote or as an alternative a better way to set environement variables for a command. Please note that I'm still on cmake 2.8, so I don't have the new "env" command available in 3.2. Thanks in advance!

请注意，这不是 cmake：何时引用变量？，因为这些引用方法都不适用于这种特殊情况。

Note that this is not a duplicate of cmake: when to quote variables? as none of those quoting methods work for this particular case.

推荐答案

明显的选择 - 通常建议在打开 COMMAND 的边界时，特别是对于较早版本的CMake - 是使用外部脚本。

The obvious choice - often recommended when hitting the boundaries of COMMAND especially with older versions of CMake - is to use an external script.

我只想添加一些简单的 COMMAND 变体，它们可以工作，不需要shell，但是我必须承认 - 仍然部分平台依赖。

I just wanted to add some simple COMMAND only variations that do work and won't need a shell, but are - I have to admit - still partly platform dependent.

• 一个例子是只将引用的部分放入变量：

• One example would be to put only the quoted part into a variable:

set(vars_as_string "-Ldir -Ldir2")
add_custom_target(
    QuotedEnvVar
    COMMAND env LD_FLAGS=${vars_as_string} | grep LD_FLAGS
)

这实际上是转义空格而不是引号。

Which actually does escape the space and not the quotes.

另一个例子是使用转义引号将其添加为启动器规则：

Another example would be to add it with escaped quotes as a "launcher" rule:

add_custom_target(
    LauncherEnvVar
    COMMAND env | grep LD_FLAGS
)
set_target_properties(
    LauncherEnvVar 
    PROPERTIES RULE_LAUNCH_CUSTOM "env LD_FLAGS=\"-Ldir -Ldir2\""
)

编辑：添加多个引号参数的示例，无需转义引号

Edit: Added examples for multiple quoted arguments without the need of escaping quotes

• 将隐藏一些复杂性在一个函数，如果你想添加到所有的自定义命令调用 - 使用全局/目录 RULE_LAUNCH_CUSTOM 属性：

function(set_env)
    get_property(_env GLOBAL PROPERTY RULE_LAUNCH_CUSTOM)
    if (NOT _env)
        set_property(GLOBAL PROPERTY RULE_LAUNCH_CUSTOM "env")
    endif()
    foreach(_arg IN LISTS ARGN)
        set_property(GLOBAL APPEND_STRING PROPERTY RULE_LAUNCH_CUSTOM " ${_arg}")
    endforeach()
endfunction(set_env)

set_env(LDFLAGS="-Ldir1 -Ldir2" CFLAGS="-Idira -Idirb")

add_custom_target(
    MultipleEnvVar
    COMMAND env | grep -E 'LDFLAGS|CFLAGS'
)

替代（适用于CMake> = 3.0）

Alternative (for CMake >= 3.0)

• 寻找这里（除了 cmake -E env ... ）被命名为 Bracket Argument ，并允许任何字符，而不需要添加反斜杠：

• I think what we actually are looking for here (besides the cmake -E env ...) is named Bracket Argument and does allow any character without the need of adding backslashes:

set_property(
    GLOBAL PROPERTY 
        RULE_LAUNCH_CUSTOM [=[env LDFLAGS="-Ldir1 -Ldir2" CFLAGS="-Idira -Idirb"]=]
)
add_custom_target(
    MultipleEnvVarNew
    COMMAND env | grep -E 'LDFLAGS|CFLAGS'
)

参考

• 0005145：为ADD_CUSTOM_COMMAND / ADD_CUSTOM_TARGET 设置环境变量


• 如何修改传递的环境变量自定义CMake目标？


• [CMake]如何为自定义命令设置环境变量


• cmake：何时引用变量？

• 0005145: Set environment variables for ADD_CUSTOM_COMMAND/ADD_CUSTOM_TARGET
• How to modify environment variables passed to custom CMake target?
• [CMake] How to set environment variable for custom command
• cmake: when to quote variables?

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