Backreferencing with sed

Question

I have a database containing a list of unsigned longs representing a bunch of memory addresses followed by an offset within two brackets (e.g. Mem[offset], 0x2322AD4[3]), and some other data. What I am trying to achieve is separate the offset from the memory address by replacing the opening bracket with a single space and get rid of the closing bracket. The procedure I'm taking goes as follows:

1. Find every digit that is followed by an opening bracket (this is because my other data may contain a bracket that should NOT be messed with).
2. Replace ONLY the bracket with a single space.
3. Find every digit that is followed by a closing bracket, and ONLY replace the closing bracket with a single space.

The brackets could be easily handled with the following two commands:

sed 's/\[/ /' #replace the opening bracket with a single space.

sed 's/\]//' #delete the closing bracket

But again, I don't want to mess with the other data stored in the database.

My second guess was getting back-referencing involved to handle the job. Is it possible to tell sed to find every digit followed by an opening brace and back-reference the digit and add a space right after it, resulting in something like this:

0x2322AD4 3]

So then I can just go ahead and use the second command mentioned above to get rid of the closing brace?

If there is a whole difference approach to solve the problem, please post.

Answer 1

I think what you're looking for is something like this:

sed -r 's/(0[xX][[:xdigit:]]+)\[([[:digit:]]+)\]/\1 \2/g'

eg:

$ sed -r 's/(0[xX][[:xdigit:]]+)\[([[:digit:]]+)\]/\1 \2/g' <<EOF
> mem+offset: 0x2322AD4[3]  0x232BEEF[12]
> unchanged: 0x22343AF word[2] 7E[word]
> EOF

mem+offset: 0x2322AD4 3  0x232BEEF 12
unchanged: 0x22343AF word[2] 7E[word]
$

Note: without the 0[xX], it would have considered d[2] to be replaceable in the second input line.

Answer 2

I was able to figure it out. Here's the answer for future visits to the question:

sed -r 's/(0[Xx][A-Fa-f0-9]+)\[([0-9]+)\]/\1 \2/g'