How to grep on gdb print

Question

Is there a way to grep on the output of print command in gdb? In my case, I am debugging a core dump using gdb and the object I am debugging contains hell lots of elements. I am

Answer 1

The simplest way is to exploit gdb python. One-liner:

gdb λ py ["attribute" in line and print(line) for line in gdb.execute("p *this", to_string=True).splitlines()]

Assuming you have enabled history of commands, you can type this just once, and later then press Ctrl+R b.exec to pull it out of history. Next simply change attribute and *this per your requirements.

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You can also make this as simple as this:

gdb λ grep_cmd "p *this" attribute

For that just add the following to your .gdbinit file:

py
class GrepCmd (gdb.Command):
    """Execute command, but only show lines matching the pattern
    Usage: grep_cmd   """

    def __init__ (_):
        super ().__init__ ("grep_cmd", gdb.COMMAND_STATUS)

    def invoke (_, args_raw, __):
        args = gdb.string_to_argv(args_raw)
        if len(args) != 2:
            print("Wrong parameters number. Usage: grep_cmd  ")
        else:
            for line in gdb.execute(args[0], to_string=True).splitlines():
                if args[1] in line:
                    print(line)

GrepCmd() # required to get it registered
end