gdb

Q: How do I install gdb?

Run npx skills add https://github.com/mohitmishra786/low-level-dev-skills --skill gdb in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/gdb/ (personal) or .claude/skills/gdb/ (project).

Q: Which AI agents can use gdb?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Q: Is gdb safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Q: Who maintains gdb?

It is published by mohitmishra786 in mohitmishra786/low-level-dev-skills. It has 939 recorded installs.

by mohitmishra786Code Quality & Workflow

GDB debugger skill for C/C++ programs. Use when starting a GDB session, setting breakpoints, stepping through code, inspecting variables, debugging crashes, using reverse debugging (record/replay), remote debugging with gdbserver, or loading core dumps. Activates on queries about GDB commands, segfaults, hangs, watchpoints, conditional breakpoints, pretty-printers, Python GDB scripting, or multi-threaded debugging.

Installs: 939
Last 24h: —
Trending rank: —
Security: Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/mohitmishra786/low-level-dev-skills --skill gdb

01
Install
Run the command in your project. The CLI asks which agents to install for.
02
Describe the task
Ask your agent for something this skill covers. It loads gdb automatically when relevant.
03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

GDB

Purpose

Walk agents through GDB sessions from first launch to advanced workflows: crash diagnosis, reverse debugging, remote debugging, and multi-thread inspection.

Triggers

"My program segfaults / crashes — how do I debug it?"
"How do I set a breakpoint on condition X?"
"How do I inspect memory / variables in GDB?"
"How do I debug a remote embedded target?"
"GDB shows ?? frames / no source"
"How do I replay a bug deterministically?" (record/replay)

Workflow

1. Prerequisite: compile with debug info

Always compile with -g (GCC/Clang). Use -Og or -O0 for most debuggable code.

gcc -g -Og -o prog main.c

For release builds: use -g -O2 and keep the binary with symbols (strip separately with objcopy).

2. Start GDB

gdb ./prog                          # load binary
gdb ./prog core                     # load with core dump
gdb -p 12345                        # attach to running process
gdb --args ./prog arg1 arg2         # pass arguments
gdb -batch -ex 'run' -ex 'bt' ./prog  # non-interactive (CI)

3. Essential commands

Command	Shortcut	Effect
`run [args]`	`r`	Start the program
`continue`	`c`	Resume after break
`next`	`n`	Step over (source line)
`step`	`s`	Step into
`nexti`	`ni`	Step over (instruction)
`stepi`	`si`	Step into (instruction)
`finish`		Run to end of current function
`until N`		Run to line N
`return [val]`		Force return from function
`quit`	`q`	Exit GDB

4. Breakpoints and watchpoints

break main                          # break at function
break file.c:42                     # break at line
break *0x400abc                     # break at address
break foo if x > 10                 # conditional break
tbreak foo                          # temporary breakpoint (fires once)
rbreak ^mylib_.*                    # regex breakpoint on all matching functions

watch x                             # watchpoint: break when x changes
watch *(int*)0x601060               # watch memory address
rwatch x                            # break when x is read
awatch x                            # break on read or write

info breakpoints                    # list all breakpoints
delete 3                            # delete breakpoint 3
disable 3                           # disable without deleting
enable 3

5. Inspect state

print x                             # print variable
print/x x                           # print in hex
print *ptr                          # dereference pointer
print arr[0]@10                     # print 10 elements of array
display x                           # auto-print x on every stop
undisplay 1

info locals                         # all local variables
info args                           # function arguments
info registers                      # all CPU registers
info registers rip rsp rbp          # specific registers
x/10wx 0x7fff0000                   # examine 10 words at address
x/s 0x400abc                        # examine as string
x/i $rip                            # examine current instruction

backtrace                           # call stack (bt)
bt full                             # bt + local vars
frame 2                             # switch to frame 2
up / down                           # move up/down the stack

6. Multi-thread debugging

info threads                        # list threads
thread 3                            # switch to thread 3
thread apply all bt                 # backtrace all threads
thread apply all bt full            # full bt all threads
set scheduler-locking on            # pause other threads while stepping

7. Reverse debugging (record/replay)

Record requires target record-full or target record-btrace (Intel PT):

# Software record (slow but universal)
record                              # start recording
run
# ... trigger the bug ...
reverse-continue                    # go back to last break
reverse-next                        # step backwards
reverse-step
reverse-finish

# Intel Processor Trace (fast, hardware)
target record-btrace pt
run
# view instruction history
record instruction-history

8. Remote debugging with gdbserver

On target:

gdbserver :1234 ./prog
# Or attach:
gdbserver :1234 --attach 5678

On host:

gdb ./prog
(gdb) target remote 192.168.1.10:1234
(gdb) break main
(gdb) continue

For cross-compilation: use aarch64-linux-gnu-gdb on the host.

9. Common problems

Symptom	Cause	Fix
`No symbol table`	Binary not compiled with `-g`	Recompile with `-g`
`??` frames in backtrace	Missing debug info or stack corruption	Install debuginfo package; check for stack smash
`Cannot access memory at address`	Null dereference / freed memory	Check pointer before deref; use ASan
`SIGABRT` in backtrace	`abort()` or assertion failure	Go up frames to find the assertion
GDB hangs on `run`	Binary waiting for input	Redirect stdin: `run < /dev/null`
Breakpoint in wrong place	Optimiser moved code	Compile with `-Og`; or use `nexti`

10. GDB init file (~/.gdbinit)

set history save on
set history size 1000
set print pretty on
set print array on
set print array-indexes on
set pagination off
set confirm off

For a command cheatsheet, see references/cheatsheet.md. For pretty-printers and Python scripting, see references/scripting.md.

Related skills

Use skills/debuggers/core-dumps for loading core files
Use skills/debuggers/lldb for LLDB-based workflows
Use skills/runtimes/sanitizers to catch bugs before needing the debugger
Use skills/compilers/gcc for -g flag details

FAQ

What does the gdb skill do?

How do I install gdb?

Run npx skills add https://github.com/mohitmishra786/low-level-dev-skills --skill gdb in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/gdb/ (personal) or .claude/skills/gdb/ (project).

Which AI agents can use gdb?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is gdb safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains gdb?

It is published by mohitmishra786 in mohitmishra786/low-level-dev-skills. It has 939 recorded installs.