How to pass arguments and redirect stdin from a file to program run in gdb

Question

I usually run a program as      a out arg1 arg2  lt file   I would like to debug it using gdb   I am aware of the set args functionality  but that only works from the gdb prompt

User · Answer

Start GDB on your project     Go to project directory  where you ve already compiled the project executable  Issue the command gdb and the name of the executable as below   gdb projectExecutablename   This starts up gdb  prints the following  GNU gdb  Ubuntu 7 11 1-0ubuntu1 16 04  7 11 1 Copyright  C  2016 Free Software Foundation  Inc                                                    Type  apropos word  to search for commands related to  word     Reading symbols from projectExecutablename   done   gdb    Before you start your program running  you want to set up your breakpoints  The break command allows you to do so  To set a breakpoint at the beginning of the function named main    gdb  b main Once you ve have the  gdb  prompt  the run command starts the executable running  If the program you are debugging requires any command-line arguments  you specify them to the run command  If you wanted to run my program on the  xfiles  file  which is in a folder  mulder  in the project directory   you d do the following    gdb  r mulder xfiles   Hope this helps    Disclaimer  This solution is not mine  it is adapted from https   web stanford edu class cs107 guide gdb html This short guide to gdb was  most probably  developed at Stanford University

User · Answer

If you want to have bare run command in gdb to execute your program with redirections and arguments  you can use set args     gdb   a out  gdb  set args arg1 arg2  lt file  gdb  run   I was unable to achieve the same behaviour with --args parameter  gdb fiercely escapes the redirections  i e     gdb --args echo 1 2   lt file   gdb  show args Argument list to give program being debugged when it is started is  1 2   lt file    gdb  run     1 2  lt file       This one actually redirects the input of gdb itself  not what we really want here    gdb --args echo 1 2  lt file zsh  no such file or directory  file

User · Answer

Pass the arguments to the run command from within gdb     gdb   a out  gdb  r  lt  t Starting program   dir a out  lt  t

User · Answer

You can do this   gdb --args path to executable -every -arg you can think  lt  of   The magic bit being --args   Just type run in the gdb command console to start debugging

User · Answer

Wouldn t it be nice to just type debug in front of any command to be able to debug it with gdb on shell level   Below it this function   It even works with following     program        lt   lt  in  1 gt   gt  out  2 gt   gt  two  3 gt   gt  three    This is a call where you cannot control anything  everything is variable  can contain spaces  linefeeds and shell metacharacters   In this example  in  out  two  and three are arbitrary other commands which consume or produce data which must not be harmed   Following bash function invokes gdb nearly cleanly in such an environment  Gist    debug       1000 lt  amp 0 1001 gt  amp 1 1002 gt  amp 2     0 lt  dev tty 1 gt  dev tty 2 gt  amp 0      usr bin gdb -q -nx -nw     -ex  set exec-wrapper  bin bash -c  exec 0 lt  amp 1000 1 gt  amp 1001 2 gt  amp 1002          exec      -ex r     --args           Example on how to apply this   Just type debug in front   Before   p     n    I  am  evil     yay      b u g     p       lt   lt  in  1 gt   gt  out  2 gt   gt  two  3 gt   gt  three    After   p     n    I  am  evil     yay     debug  b u g     p       lt   lt  in  1 gt   gt  out  2 gt   gt  two  3 gt   gt  three    That s it   Now it s an absolute no-brainer to debug with gdb   Except for a few details or more    gdb does not quit automatically and hence keeps the IO redirection open until you exit gdb   But I call this a feature  You cannot easily pass argv0 to the program like with exec -a arg0 command args   Following should do this trick  After exec-wrapper change  exec to  exec -a      DEBUG ARG0 -  1     There are FDs above 1000 open  which are normally closed   If this is a problem  change 0 lt  amp 1000 1 gt  amp 1001 2 gt  amp 1002 to read 0 lt  amp 1000 1 gt  amp 1001 2 gt  amp 1002 1000 lt  amp - 1001 gt  amp - 1002 gt  amp - You cannot run two debuggers in parallel   There also might be issues  if some other command consumes  dev tty  or STDIN    To fix that  replace  dev tty with    DEBUGTTY - dev tty     In some other TTY type tty  sleep inf and then use the printed TTY  i  E   dev pts 60  for debugging  as in DEBUGTTY  dev pts 60 debug command arg     That s the Power of Shell  get used to it    Function explained    1000 lt  amp 0 1001 gt  amp 1 1002 gt  amp 2 moves away the first 3 FDs   This assumes  that FDs 1000  1001 and 1002 are free  0 lt  dev tty 1 gt  dev tty 2 gt  amp 0 restores the first 3 FDs to point to your current TTY   So you can control gdb   usr bin gdb -q -nx -nw runs gdb invokes gdb on shell -ex  set exec-wrapper  bin bash -c  exec 0 lt  amp 1000 1 gt  amp 1001 2 gt  amp 1002          creates a startup wrapper  which restores the first 3 FDs which were saved to 1000 and above -ex r starts the program using the exec-wrapper --args      passes the arguments as given   Wasn t that easy

[c++] How to pass arguments and redirect stdin from a file to program run in gdb?

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