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diff --git a/src/gdb.md b/src/gdb.md deleted file mode 100644 index 7a43ca1..0000000 --- a/src/gdb.md +++ /dev/null @@ -1,162 +0,0 @@ -# gdb(1) - -# CLI - -```markdown - gdb [opts] [prg [-c coredump | -p pid]] - gdb [opts] --args prg <prg-args> - opts: - -p <pid> attach to pid - -c <coredump> use <coredump> - -x <file> execute script <file> before prompt - -ex <cmd> execute command <cmd> before prompt - --tty <tty> set I/O tty for debugee -``` - -# Interactive usage - -```markdown - tty <tty> - Set <tty> as tty for debugee. - Make sure nobody reads from target tty, easiest is to spawn a shell - and run following in target tty: - > while true; do sleep 1024; done - - set follow-fork-mode <child | parent> - Specify which process to follow when debuggee makes a fork(2) - syscall. - - sharedlibrary [<regex>] - Load symbols of shared libs loaded by debugee. Optionally use <regex> - to filter libs for symbol loading. - - break [-qualified] <sym> thread <tnum> - Set a breakpoint only for a specific thread. - -qualified: Tred <sym> as fully qualified symbol (quiet handy to set - breakpoints on C symbols in C++ contexts) - - rbreak <regex> - Set breakpoints matching <regex>, where matching internally is done - on: .*<regex>.* - - command [<bp_list>] - Define commands to run after breakpoint hit. If <bp_list> is not - specified attach command to last created breakpoint. Command block - terminated with 'end' token. - - <bp_list>: Space separates list, eg 'command 2 5-8' to run command - for breakpoints: 2,5,6,7,8. - - info functions [<regex>] - List functions matching <regex>. List all functions if no <regex> - provided. - - info variables [<regex>] - List variables matching <regex>. List all variables if no <regex> - provided. - - info handle [<signal>] - Print how to handle <signal>. If no <signal> specified print for all - signals. - - handle <signal> <action> - Configure how gdb handles <signal> sent to debugee. - <action>: - stop/nostop Catch signal in gdb and break. - print/noprint Print message when gdb catches signal. - pass/nopass Pass signal down to debugee. - - catch signal <signal> - Create a catchpoint for <signal>. -``` - -# User commands (macros) - -Gdb allows to create & document user commands as follows: -```markdown - define <cmd> - # cmds - end - - document <cmd> - # docu - end -``` - -To get all user commands or documentations one can use: -```markdown - help user-defined - help <cmd> -``` - -# Hooks - -Gdb allows to create two types of command `hooks` -- `hook-` will be run before `<cmd>` -- `hookpost-` will be run after `<cmd>` -```markdown - define hook-<cmd> - # cmds - end - - define hookpost-<cmd> - # cmds - end -``` - -# Examples - -## Catch SIGSEGV and execute commands -This creates a `catchpoint` for the `SIGSEGV` signal and attached the `command` -to it. -```markdown - catch signal SIGSEGV - command - bt - c - end -``` - -## Run `backtrace` on thread 1 (batch mode) -```markdown - gdb --batch -ex 'thread 1' -ex 'bt' -p <pid> -``` - -## Script gdb for automating debugging sessions -To script gdb add commands into a file and pass it to gdb via `-x`. -For example create `run.gdb`: -```markdown - set pagination off - - break mmap - command - info reg rdi rsi rdx - bt - c - end - - #initial drop - c -``` -This script can be used as: -```markdown - gdb --batch -x ./run.gdb -p <pid> -``` - -# Know Bugs - -## Workaround `command + finish` bug -When using `finish` inside a `command` block, commands after `finish` are not -executed. To workaround that bug one can create a wrapper function which calls -`finish`. -```markdown - define handler - bt - finish - info reg rax - end - - command - handler - end -``` |