如何正确逃生在Makefile的数据？ [英] How do I properly escape data for a Makefile?
问题描述
我在动态生成 config.mk 与将由一个Makefile中使用bash脚本。该文件被构造有：
I'm dynamically generating config.mk with a bash script which will be used by a Makefile. The file is constructed with:
cat > config.mk <<CFG
SOMEVAR := $value_from_bash1
ANOTHER := $value_from_bash2
CFG
我如何确保所生成的文件真的包含 $ value_from_bash的内容* ，并没有什么扩展/间preTED？我可能需要逃避 $ 到 $ 和 \\ 到 \\\\ ，但是否有需要进行转义其他字符？或许有一个特殊的文本分配我还没有听说过？
How do I ensure that the generated file really contains the contents of $value_from_bash*, and not something expanded / interpreted? I probably need to escape $ to $$ and \ to \\, but are there other characters that needs to be escaped? Perhaps there is a special literal assignment I've not heard of?
空间似乎是太麻烦：
$ ls -1
a b
a
$ cat Makefile
f := a b
default_target:
echo "$(firstword $(wildcard ${f}))"
$ make
a
如果我用 F：= A \\ B 它的工作原理（使用引号如 F：='A B 没有任何工作，生成文件只是把它当作一个普通字符）
If I use f := a\ b it works (using quotes like f := 'a b' did not work either, makefile just treats it as a regular character)
推荐答案
好吧，事实证明，Makefile中需要很少的转义本身，而这是由外壳间preTER执行的命令的需求被转义。
Okay, it turned out that Makefiles needs little escaping for itself, but the commands which are executed by the shell interpreter needs to be escaped.
这在Makefile的特殊含义，需要被转义字符是：
Characters which have a special meaning in Makefile and that needs to be escaped are:
- 锐（
＃，评论）成为\\＃ - 美元（
$，开始变的）变成$
- sharp (
#, comment) becomes\# - dollar (
$, begin of variable) becomes$$
换行不能插入一个变量，但要避免破坏Makefile文件，prePEND它的其余部分用反斜杠所以换行符将被忽略
Newlines cannot be inserted in a variable, but to avoid breaking the rest of the Makefile, prepend it with a backslash so the line break will be ignored
太糟糕了，反斜杠本身不能逃脱（ \\\\ 将仍然是 \\\\ ，而不是 \\ 如您所期望的那样）。这使得不可能把一个文字斜线上的字符串的结束，因为这将要么吃换行符或以下注释的哈希值。空格可以放在该行的结束，但还会放在变量本身。
Too bad that a backslash itself cannot be escaped (\\ will still be \\ and not \ as you might expect). This makes it not possible to put a literal slash on the end of a string as it will either eat the newline or the hash of a following comment. A space can be put on the end of the line, but that'll also be put in the variable itself.
配方本身是作为PTED shell命令间$ P $，没有任何花哨的转义，所以你自己逃跑的数据，试想一下，你正在写一个shellscript里和其他文件中插入的变量。该战略在这里要放单引号之间的变量逃脱唯一 与'\\''（将关闭字符串插入文字 ，并开始一个新的字符串）。例如：早上，所有变成'晨'\\''所有'相当于 早上所有。
The recipe itself is interpreted as a shell command, without any fancy escaping, so you've to escape data yourself, just imagine that you're writing a shellscript and inserting the variables from other files. The strategy here would be putting the variables between single quotes and escape only ' with '\'' (close the string, insert a literal ' and start a new string). Example: mornin' all becomes 'morning'\'' all' which is equivalent to "morning ' all".
该firstword +通配符问题是由带空格的文件名是由 firstword 作为单独的文件名对待这一事实造成的。此外，通配符使用扩展逃逸 \\ 所以 XY ，而不是两个单词。
The firstword+wildcard issue is caused by the fact that filenames with spaces in them are treated as separate filenames by firstword. Furthermore, wildcard expands escapes using \ so x\ y is matches as one word, x y and not two words.
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