Debugging with GDB

Node:Starting, Next:Arguments, Previous:Compilation, Up:Running

### Starting your program

`run`
`r`
  Use the `run` command to start your program under GDB. You must first specify the program name (except on VxWorks) with an argument to GDB (see Getting In and Out of GDB), or by using the `file` or `exec-file` command (see Commands to specify files).

If you are running your program in an execution environment that supports processes, `run` creates an inferior process and makes that process run your program. (In environments without processes, `run` jumps to the start of your program.)

The execution of a program is affected by certain information it receives from its superior. GDB provides ways to specify this information, which you must do before starting your program. (You can change it after starting your program, but such changes only affect your program the next time you start it.) This information may be divided into four categories:

The arguments.
  Specify the arguments to give your program as the arguments of the `run` command. If a shell is available on your target, the shell is used to pass the arguments, so that you may use normal conventions (such as wildcard expansion or variable substitution) in describing the arguments. In Unix systems, you can control which shell is used with the `SHELL` environment variable. See Your program's arguments.
The environment.
  Your program normally inherits its environment from GDB, but you can use the GDB commands `set environment` and `unset environment` to change parts of the environment that affect your program. See Your program's environment.
The working directory.
  Your program inherits its working directory from GDB. You can set the GDB working directory with the `cd` command in GDB. See Your program's working directory.
The standard input and output.
  Your program normally uses the same device for standard input and standard output as GDB is using. You can redirect input and output in the `run` command line, or you can use the `tty` command to set a different device for your program. See Your program's input and output.

  Warning: While input and output redirection work, you cannot use pipes to pass the output of the program you are debugging to another program; if you attempt this, GDB is likely to wind up debugging the wrong program.

When you issue the `run` command, your program begins to execute immediately. See Stopping and continuing, for discussion of how to arrange for your program to stop. Once your program has stopped, you may call functions in your program, using the `print` or `call` commands. See Examining Data.

If the modification time of your symbol file has changed since the last time GDB read its symbols, GDB discards its symbol table, and reads it again. When it does this, GDB tries to retain your current breakpoints.