1.2.2.3.3.
Interactive shell behavior
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Differences in interactive mode:
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Bash reads startup files.
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Job control enabled by default.
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Prompts are set, PS2 is enabled for multi-line commands, it is usually set to ">". This is also the prompt you get when the shell thinks you entered an unfinished command, for instance when you forget quotes, command structures that cannot be left out, etc.
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Commands are by default read from the command line using readline.
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Bash interprets the shell option ignoreeof instead of exiting immediately upon receiving EOF (End Of File).
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Command history and history expansion are enabled by default. History is saved in the file pointed to by HISTFILE when the shell exits. By default, HISTFILE points to ~/.bash_history.
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Alias expansion is enabled.
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In the absence of traps, the SIGTERM signal is ignored.
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In the absence of traps, SIGINT is caught and handled. Thus, typing Ctrl+C, for example, will not quit your interactive shell.
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Sending SIGHUP signals to all jobs on exit is configured with the huponexit option.
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Commands are executed upon read.
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Bash checks for mail periodically.
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Bash can be configured to exit when it encounters unreferenced variables. In interactive mode this behavior is disabled.
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When shell built-in commands encounter redirection errors, this will not cause the shell to exit.
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Special built-ins returning errors when used in POSIX mode don't cause the shell to exit. The built-in commands are listed in Section 1.3.2.
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Failure of exec will not exit the shell.
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Parser syntax errors don't cause the shell to exit.
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Simple spell check for the arguments to the cd built-in is enabled by default.
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Automatic exit after the length of time specified in the TMOUT variable has passed, is enabled.
More information:
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See Chapter 12 for more about signals.
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Section 3.4 discusses the various expansions performed upon entering a command.
