Relevant gdb commands I've gathered over time: info gdb //Manual info locals //Vars in local scope info variables //Vars declared outside current scope info functions //Names and datatypes of all defined functions info b //List all breakpoints break funcName //Set breakpoint at function funcName (short: b funcName) break file::line //Set breakpoint at line in file layout next //Cycle through the layouts of gdb p var //Print the value of variable var p var = value //Force set value to a var run //Start the program start //Synonymous to (b main && run). Puts temporary b at main next //Execute the current line in source (short: n) step //Step into function call at current line (short: s) finish //Finish the execution of current function (short: fin) continue //Resume execution (After a breakpoint) (short: c) refresh //Repaint the interface (To fix corrupted interface) shell cmd //Run shell command cmd from gdb prompt python gdb.execute(cmd) //Run a gdb command cmd from python prompt set print pretty on //Enable pretty printing (Put in ~/.gdbinit) $ gdb -c core.num //Examine the dumped core file from a SIGSEGV(shell command) bt //Print backtrace break _exit //Breakpoint at exit of program whatis expr //Print datatype of expr ptype expr //Detailed print of datatype of expr watch var //Stop when var is modified watch -l foo //Watch foo loaction rwatch foo //Stop when foo is read watch foo if foo>10 //Watch foo conditionally delete //Delete all breakpoints delete breakpoint_no //Delete breakpoint breakpoint_no command breakpoint_no //Run user listed commands when breakpoint is hit (End list of commands with 'end') file executable //Load the executable for debugging from inside gdb quit //Quit (short: q) Feel free to correct/add any useful command you know.

That's how KZfaq should be used.

Great explanation! You have really made me start to like this tool.

very well explained, a quick grab for the beginners.

2021 and this is still a great Quick Start vid.

Wow ! That was Crisp & Clear :)

gcc -g factorial.c -o factorial should be first line

fantastic tutorial, thank you!

This is an excellent tutorial to get started with gdb .

neat and comprehensible to begin. thank you

fantastic explanation and delivery. Thank you.

I could have used this last night. Glad I looked up gnu debugger. I figured there was one but didn't know. I installed MSVC instead but decided to check just to be sure if gdb did exist. This is so much easier. I just have to get used to it. I was working on "the reference" last night. exercise 1-12. Couldn't figure out why my program kept newlining spaces. Well I found out it was because where I put the trigger to determine where a new word begins. I should have done it once it finds a new word. Not once the current word is done. Different ways of thinking I suppose. I suppose I could have done it the first way but it was easier for me to ignore spaces this way. Its my third time reading the book and I never got past this chapter. However I have read other C books to entirety. This one is different. This one makes you work a lot more. However how concise the exercises are they do give you hints in the previous chapters. So your not entirely blind. I should have seen this in the previous attempts at reading the book. Thanks for this tutorial. I am going to have to watch it again and again and again.

Best video on the topic. Thanks!

Very nice intro to gdb in action on a real problem. thanks!

you forgot to mention one of the most important things in gdb ! x ! the examine function ! its used to examine the registers and see what they point to (the address) and you can get the output in different ways for example: x/x $eip for displaying the value of eip in hexadecimal x/o $eip for displaying the value of eip in octal x/u $eip for displaying the value of eip in unsigned base-10 decimal x/t $eip for displaying the value of eip in binary x/i $eip for examining the instruction and you can choose the size for example x/2xb $eip for displaying first 2 bytes in hexadecimal x/1xh $eip it gives the same amount of bytes but in one line (h stands for half word which is a short (2 bytes)) or you can use dw (double word 4bytes) and word is 4 bytes as well (w) and you can use the address of the register instead of referencing to it by $eip (info register eip/info registers) oh and you can use type g for giant (8bytes) so display system: o : octal u : unsigned t : binary x : hexadecimal and sizes: w : word (4 bytes) dw : double word(4 bytes) g : giant (8 bytes) h : half word (2 bytes) b : byte (1 byte) so the format is like that: x/ (the examine function) and it takes two arguments the (register/memory address/varible) + display type extra examples: x/x $esp x/o $ebp x/u $eip x/t $edi print $eip (it will make a variable for it and it will display the value and the address) x/2xw $1 and and by the way gdb uses little endian format so the bytes will be reversed for example : x/4xb $eip : 0x7c , 0x4f , 45 , 64 x/1xw $eip: 0x64454f7c why ? : if its not reversed like this : 0x7c4f4564 0x7c = 124 in decimal 0x4f = 79 in decimal 0x45 = 69 in decimal 0x64 = 40 in decimal so : if we do it without reversing it would be: 124*(256^3) + 79*(256^2) + 69*(256^1) + 40*(256^0) = 2085569832 incorrect but 40*(256^3) + 69*(256^2) + 79*(256^1) + 124*(256^0) = 675630972 correct so hope that helped :) i was just bored and though of explaining something and if anyone needs helps add me on Skype waleedking111 and send me a message

Thank you teaching us. Looking forward to learn more.

Thank you for this great video! I Enjoyed it. Well explained ;)

very helpful intro to gdb, thanks!

Great explanation. Thanks!

great video, clear and to the point

Very Concise and precise

This is super helpful. Thanks!

Great explanation and presentation style.

Well explained. Nice job

Great video! Thank you!

Thanks, great explanation for beginners.

Excellent tutorial!

Very well explanation, Thanks.

It was a great tutorial.Thanks

Excellent man! Thanks! it was really helpful!

excellent intro thanks

Brilliant !

excellent explanation !

excellent presentation - thank you

Good video, thank you.

That was very helpful dude

Very nice , thanks.

Amazing video👍

you are too good at teaching

very helpful and straight to the point thank you

Very Good Video Bro.. But can u tell me whts the difference between Continue and next command ? Sometimes u have used next and later u used continue.

Nice presentation man.. :)

NIce video.

When I set "break main", enter "r", enter "n" the debugger runs until the end of program.

wow great work thanks a lot. ur body language is so funny lol

"Good explanation..."

awesome!

thank you

how can I get similar syntax highlighting for C in vim?

thanks boss

doesnt eclipse have something like this built in?

good video

Could someone let me know the content of his ~vimrc? I would like to get the same color and line number please..

Que lejos has llegado Jolimbo.

two likes -just because you started with how to quit? it is most imprtant indeed.. (y)(y) nice tutorial :-)

I'm not sure how you make a GDB tutorial without telling people to compile with the -g flag, and make sure you aren't employing optimization. So, don't use any -O compiler flags while debugging. Other than that, it's a good tutorial on the basics.

can you please help me gdb-4.16 which Ubuntu version support

The quality of this tutorial is good, but it's really slow.

Thanks, I've forgot how to use debuggers for 15 odd years (thanks Borland C/C++) also tutorial start at 2:35

Good 1

Why is 'quit' shortened to 'q'? How lazy are we meant to be? I get that commands that are typed hundreds of times per session should be as short as possible but a command that it used once a session at most doesn't need to be that short.

04:02 If only I could do that with my GDB... :/ (i.e. fade out all that unnecessary junk and let just the current line of source code and perhaps the command line just below it to show clearly) 04:57 Here's another place where this difference in shades of grey would help a lot visually, if the current line of code were highlighted.

Hmm. I saw some good options in GDB that some of the IDEs do not have. Though it seems I'll debug faster with regular IDEs. Am I wrong guys? More difficult to read, can't "watch" class/struct type variables, 2 key strokes to iterate the code etc. All in all, it seems more difficult to debug with this compared to Eclipse etc.

Providing a link to the original video would've been the right thing to do.

how it's shows source code if it's compiled to binary, how it's even knows exact variable names?

But can gdb help me report misogynist attack and rape threats?

hello fellow virgins

Hello , i would like make a question, my lldb on OSX Mavericks show code in assembly , so i don't no how chance it to C code , Plz Can you help me solve it?

great tutorial but damn that body language is a bit disturbing.

I really have fun now

I saw the bug at the start of this video.

Looks like he is booting too much

Bro please stop moving your shoulders.

dafuq bro your intro video sound is terrible i was wearing my head phones ........It almost made me deaf...............

Quit moving around. Just stand there and talk. Better, don't appear in the video. Simply show your source code and narrate.