Tutorial Complete

GDB-Commands-Scripts-Workflow.adoc

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+= *GDB Commands, Scripts and Workflow*
+
+=== Breakpoints and Commands -- save time!
+
+In order to display some specific information when we reach a breakpoint,
+we can achieve this by `(gdb)command` command in gdb.
+[source,]
+----
+(gdb) command 1
+Type commands for breakpoint(s) 1, one per line.
+End with a line saying just "end".
+>print arr
+>print size
+>end
+----
+
+Here, the argument to "command" is the index of the breakpoint to which
+these print commands will be associated to.
+
+
+=== define your own commands
+
+In order to define bunch of command give it a name like a alias
+we can use `define <alias>`.
+[source,]
+----
+(gdb) define log
+Type commands for definition of "log".
+End with a line saying just "end".
+>info args
+>info frame
+>bt
+>end
+----
+[source,]
+----
+Temporary breakpoint 1, main () at array.c:34
+34      int main () {
+(gdb) log
+No arguments.
+Stack level 0, frame at 0x7fffffffe230:
+ rip = 0x555555555217 in main (array.c:34); saved rip = 0x7ffff7c2a1ca
+ source language c.
+ Arglist at 0x7fffffffe220, args:
+ Locals at 0x7fffffffe220, Previous frame's sp is 0x7fffffffe230
+ Saved registers:
+  rbp at 0x7fffffffe220, rip at 0x7fffffffe228
+#0  main () at array.c:34
+----
+
+To redefine the same alias like in the above example 'log' we can use 
+the same command `define log`
+
+=== gdb scripts
+
+It is like a .vimrc for gdb.
+
+It is named as *.gdbinit* and it is defined in home (~/) directory
+and, if we want, can be overridden by defining the *.gdbinit*
+in the current directory.
+
+In this script, we can `define` command to define aliases and
+print some message, etc.
+
+=== Shell commands within GDB (shell, make and pipe)
+
+To run shell commands within GDB use keyword `shell` with respective 
+shell command like `ls` as an argument.
+[source,]
+----
+$ gdb ./main --silent
+Reading symbols from ./main...
+(gdb) shell ls
+add    array    assertion      core.14804     gcore_example.c  infinite.c  leak.c  main.c  memory.c  segfault.c
+add.c  array.c  assertion.cpp  gcore_example  infinite         leak        main    memory  segfault
+----
+
+We can also use `make` command within GDB to compile the excutable
+from gdb itself.
+
+Now when you compile the executable within GDB using `make` command,
+there are two senario which arises.
+
+*Senario 1*
+
+_When the name of the program remain same._
+
+In this case, we can simply start the execution of program from
+the beginning again.
+
+Use `start` command to do so.
+
+
+*Senario 2*
+
+_When the name of the program changes_
+
+In this cae, we can load the executable to the running gdb using `file`
+command and start the executation again.
+[source,]
+----
+(gdb)file ./<executable>
+----
+
+=== Edit source files within GDB
+
+To edit current source in gdb without exiting out of the GDB session,
+we can use `edit` command to open the source file in editor to run the 
+program. Make sure that the there is a environment variable `EDITOR=<editor-name>` defined and exported so that GDB can use it.
+[source,]
+----
+(gdb)edit 5
+----
+
+Load the program again with successful compilation to see the changes made.
+
+