Executing Commands
| Simple Command Expansion | How Bash expands simple commands before executing them. | 
| Command Search and Execution | How Bash finds commands and runs them. | 
| Command Execution Environment | The environment in which Bash executes commands that are not shell builtins. | 
| Environment | The environment given to a command. | 
| Exit Status | The status returned by commands and how Bash interprets it. | 
| Signals | What happens when Bash or a command it runs receives a signal. | 
    Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
Licensed under the GNU Free Documentation License.
    https://www.gnu.org/software/bash/manual/html_node/Executing-Commands.html