Shell Commands (Debugging with GDB)

2.3 Shell Commands

If you need to execute occasional shell commands during your debugging session, there is no need to leave or suspend GDB; you can just use the shell command.

shell command-string

!command-string

Invoke a standard shell to execute command-string. Note that no space is needed between ! and command-string. On GNU and Unix systems, the environment variable SHELL, if it exists, determines which shell to run. Otherwise GDB uses the default shell (/bin/sh on GNU and Unix systems, cmd.exe on MS-Windows, COMMAND.COM on MS-DOS, etc.).

The utility make is often needed in development environments. You do not have to use the shell command for this purpose in GDB:

make make-args

Execute the make program with the specified arguments. This is equivalent to ‘shell make make-args’.

pipe [command] | shell_command

| [command] | shell_command

pipe -d delim command delim shell_command

| -d delim command delim shell_command

Executes command and sends its output to shell_command. Note that no space is needed around |. If no command is provided, the last command executed is repeated.

In case the command contains a |, the option -d delim can be used to specify an alternate delimiter string delim that separates the command from the shell_command.

Example:

(gdb) p var
$1 = {
  black = 144,
  red = 233,
  green = 377,
  blue = 610,
  white = 987
}

(gdb) pipe p var|wc
      7      19      80
(gdb) |p var|wc -l
7

(gdb) p /x var
$4 = {
  black = 0x90,
  red = 0xe9,
  green = 0x179,
  blue = 0x262,
  white = 0x3db
}
(gdb) ||grep red
  red => 0xe9,

(gdb) | -d ! echo this contains a | char\n ! sed -e 's/|/PIPE/'
this contains a PIPE char
(gdb) | -d xxx echo this contains a | char!\n xxx sed -e 's/|/PIPE/'
this contains a PIPE char!
(gdb)

The convenience variables $_shell_exitcode and $_shell_exitsignal can be used to examine the exit status of the last shell command launched by shell, make, pipe and |. See Convenience Variables.