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### 4.3 Your Program's Arguments

The arguments to your program can be specified by the arguments of the `run` command. They are passed to a shell, which expands wildcard characters and performs redirection of I/O, and thence to your program. Your `SHELL` environment variable (if it exists) specifies what shell gdb uses. If you do not define `SHELL`, gdb uses the default shell (`/bin/sh` on Unix).

On non-Unix systems, the program is usually invoked directly by gdb, which emulates I/O redirection via the appropriate system calls, and the wildcard characters are expanded by the startup code of the program, not by the shell.

`run` with no arguments uses the same arguments used by the previous `run`, or those set by the `set args` command.

`set args`
  Specify the arguments to be used the next time your program is run. If `set args` has no arguments, `run` executes your program with no arguments. Once you have run your program with arguments, using `set args` before the next `run` is the only way to run it again without arguments.

`show args`
  Show the arguments to give your program when it is started.