Replace strings in object file

Question

I have an object file under Linux with a lot of strings in it. I would like to replace all strings that represent a specific path in this object.

I can see all the strings I need to change using the strings utility.

Is there a way to replace all these strings at once ?

The path I want to change is shorter, so it should be relatively easy, just adding terminating zeros at the end of the strings so it will remain the same length on the file.

I can write a short program that does this, but I wonder if there's already a tool I can use for this.

Answer 1

Here's a way to do that using Perl:

perl -pi -e 's/pattern/replacement/g' binaryfile

For example, I created this trivial C++ program:

// silly.cpp
#include <iostream>
#include <string>

int main()
{
    std::string name("Mellowcandle");
    std::cout << "The name is " << name << std::endl;
    std::cout << "One could call this person " << name << std::endl;
    return 0;
}

After compiling and linking it, I used this on the binary:

perl -pi -e 's/Mellowcandle/Edward\0\0\0\0\0\0/g' silly

which gives the intended effect. Note that failing to pad the replacement string to the longer string length will cause those bytes to simply be omitted, causing a segfault or worse if you try to run the resulting binary.

Answer 2

Edward's Perl answer is great, so normally I wouldn't post another answer, but in response to the other part of your question...

I wonder if there's already a tool I can use for this.

Yes, pretty much every decent hex editor has a global search-and-replace function. 010 Editor runs on Linux and definitely supports this functionality.