Software :: General Tool To Manipulate Text Configuration Files

Is there any Linux tool to create new or modify exiting key/value pairs in text configuration files? For example, to change a setting in xorg.conf, or change something in etc/networking/interfaces? I know it could be done by sed or by perl scripts, but it could be easier to have a program for this purpose. There are many difficulties for this job that the program should consider, and I am facing nearly all of them:

- Some configuration files may have sections. Like in Windows-type INI files (for example: "[something]"), or like Section in xorg.conf. More sections with the same name can occur, like in xorg.conf.

- If the key/value pair originally does not exist, then the program should add it. But not to the end of the file, but tothe end of a predefined section.

- Config files can have remark lines. Remark text can be even at the same line than the key/value pair. After modifying the value, the original remark text should not change at the end of the line. The remark-starting symbol is not always.
- The values in configuration files are not always simple numbers or simple words, but in rare cases, they are composed by more words, for example: item=name address phone

And of course, we can have remark at the end, like this: item=name address phone # remark text

- The key-value separator depends on the file. Some files use "key=value" format, some other use "key value" format, or even "key1 key2 value", like xorg.conf. The as separator can also occur.

- Case sensitivity can also be an issue.

- Sometime to desired task is not to modify a value, but to add or remove a line beginning remark to a certain line.

I think that managing all these possible cases by a perl or sed program is nearly impossible. I begun to write a C program, but maybe there is already one?