"Names starting with $ refer to registers (with the values they would have if the program were to return to the stack frame now selected, restoring all registers saved by frames farther in) or else to debugger "convenience" variables (any such name not a known register). Use assignment expressions to give values to convenience variables."
above line are from help print in gdb. can someone please explain above lines.specially which register is being referred here? Thanks.
It is referring to CPU registers. For example, EAX, ECX, ESP, EIP...
So, according to the man page, print is to "Display the value of an expression." So, these would be talking about the register values in your CPU at the current breakpoint. Here is some detailed information on debugging register values.
GDB has four "standard" register names that are available (in expressions) on most machines--whenever they do not conflict with an architecture's canonical mnemonics for registers. The register names $pc and $sp are used for the program counter register and the stack pointer. $fp is used for a register that contains a pointer to the current stack frame, and $ps is used for a register that contains the processor status. For example, you could print the program counter in hex with
You can get more information on what registers are available to you with
info registers
and
info all-registers
and then additional information on a particular register with
info registers register_name
Hope this helps!