How to Search on Github to Get Exact String Matches, Including Special Characters

You couldn't (before 2022). The official GitHub searching rules:

Due to the complexity of searching code, there are a few restrictions on how searches are performed:

• Only the default branch is considered. In most cases, this will be the master branch.
• Only files smaller than 384 KB are searchable.
• Only repositories with fewer than 500,000 files are searchable.
• You must always include at least one search term when searching source code. For example, searching for language:go is not valid, while amazing language:go is.
• At most, search results can show two fragments from the same file, but there may be more results within the file.
• You can't use the following wildcard characters as part of your search query:
  . , : ; / \ ` ' " = * ! ? # $ & + ^ | ~ < > ( ) { } [ ]
  The search will simply ignore these symbols.

Update: GitHub supports literal strings now, but you can also try some more powerful ways below.

Try Sourcegraph

For complex search with regex support try Sourcegraph.