问题
I need to parse the $PATH environment variable in my application.
So I was wondering what escape characters would be valid in $PATH.
I created a test directory called /bin:d and created a test script called
funny inside it. It runs if I call it with an absolute path.
I just can't figure out how to escape : in $PATH I tried escaping the
colon with \ and wrapping it into single ' and double " quotes.
But always when I run which funny it can't find it.
I'm running CentOS 6.
回答1:
This is impossible according to the POSIX standard. This is not a function of a specific shell, PATH handling is done within the execvp function in the C library. There is no provision for any kind of quoting.
This is the reason why including certain characters (anything not in the "portable filename character set" - colon is specifically called out as an example.) is strongly recommended against.
From SUSv7:
Since
<colon>is a separator in this context, directory names that might be used in PATH should not include a<colon>character.
See also source of GLIBC execvp. We can see it uses the strchrnul and memcpy functions for processing the PATH components, with absolutely no provision for skipping over or unescaping any kind of escape character.
回答2:
Looking at the function
extract_colon_unit
it seems to me that this is impossible. The : is unconditionally and
inescapably used as the path separator.
Well, this is valid at least for bash. Other shells may vary.
回答3:
You could try mounting it
mount /bin:d /bind
PATH=/bind
回答4:
According to http://tldp.org/LDP/abs/html/special-chars.html single quotes should preserve all special characters, so without trying it, I would think that '/bin:d' would work (with)in $PATH.
来源：https://stackoverflow.com/questions/14661373/how-to-escape-colon-in-path-on-unix