gdb how to print the current line or find the current line number

Question

list commands prints a set of lines  but I need one single line  where I am and where an error has probably occurred

User · Answer

Keep in mind that gdb is a powerful command -capable of low level instructions- so is tied to assembly concepts.

What you are looking for is called de instruction pointer, i.e:

The instruction pointer register points to the memory address which the processor will next attempt to execute. The instruction pointer is called ip in 16-bit mode, eip in 32-bit mode,and rip in 64-bit mode.

more detail here

all registers available on gdb execution can be shown with:

(gdb) info registers

with it you can find which mode your program is running (looking which of these registers exist)

then (here using most common register rip nowadays, replace with eip or very rarely ip if needed):

(gdb)info line *$rip

will show you line number and file source

(gdb) list *$rip

will show you that line with a few before and after

but probably

(gdb) frame

should be enough in many cases.

User · Answer

Command where or frame can be used  where command will give more info with the function name

User · Answer

The  frame  command will give you what you are looking for   This can be abbreviated just  f    Here is an example    gdb  frame   0  zmq  xsub t  xrecv  this 0x617180  msg  0x7ffff00008e0  at xsub cpp 139 139         int rc   fq recv  msg     gdb    Without an argument   frame  just tells you where you are at  with an argument it changes the frame   More information on the frame command can be found here

User · Answer

All the answers above are correct  What I prefer is to use tui mode  ctrl X A or  tui enable   which shows your location and the function in a separate window which is very helpful for the users  Hope that helps too

User · Answer

I do get the same information while debugging  Though not while I am checking the stacktrace  Most probably you would have used the optimization flag I think  Check this link - something related    Try compiling with -g3 remove any optimization flag   Then it might work   HTH

[debugging] gdb: how to print the current line or find the current line number?

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