Sed, is it possible to match everything between two chars?

In a script that I have to use there is a bug. The script has to replace the value of

#define MAPPING,

The line containing the bug is the one below:

sed -i -e "s/#define MAPPING \"\"/#define MAPPING \"$string\"/1" file.hpp

Since in file.hpp MAPPING is defined as: #define MAPPING ""

the script works, but if I try to call the script again and MAPPING was already redefined, now sed won't match #define MAPPING "" and thus not override anything.

I'm not a sed expert, and with a quick search couldn't find the way to let it match #define MAPPING "<everything>".

Is it possible to achieve this?

CodePudding user response：

This is does you want:

sed -Ei 's/(#define MAPPING ")[^"]*(")/\1'"$string\2/" file.hpp

• [^"]* means zero or more non double quote characters.
• I used back references instead of repeating the same text, it's up to you.
• 1 at the end of your example means replace the first occurence. However this is the default, so it can be removed.
• Be aware: if $string contains sequences like &, \5, or \\, they won't be passed literally, and can even cause an error. Also, C escapes like \t for tab are expanded by many sed implementations (so you'll end up with a literal tab in the file, instead of \t).

For what it's worth, this sed does the same thing, but is more accomodating of varied whitespace:

sed -Ei 's/(^[[:space:]]*#[[:space:]]*define[[:space:]] MAPPING[[:space:]] ")[^"]*(")/\1'"$string\2/" file.hpp

CodePudding user response：

You can also try:

sed -i -e "s/#define MAPPING \".*\"/#define MAPPING \"$string\"/1" file.hpp

The dot means anything can go here and the star means at least 0 times so .* accepts any sequence of characters, including an empty string.