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(bashref.info)Interactive Shell Behavior

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Interactive Shell Behavior
--------------------------

   When the shell is running interactively, it changes its behavior in
several ways.

  1. Startup files are read and executed as described in Note: Bash
     Startup Files.

  2. Job Control (Note: Job Control) is enabled by default.  When job
     control is in effect, Bash ignores the keyboard-generated job
     control signals `SIGTTIN', `SIGTTOU', and `SIGTSTP'.

  3. Bash expands and displays `PS1' before reading the first line of a
     command, and expands and displays `PS2' before reading the second
     and subsequent lines of a multi-line command.

  4. Bash executes the value of the `PROMPT_COMMAND' variable as a
     command before printing the primary prompt, `$PS1' (Note: Bash
     Variables).

  5. Readline (Note: Command Line Editing) is used to read commands
     from the user's terminal.

  6. Bash inspects the value of the `ignoreeof' option to `set -o'
     instead of exiting immediately when it receives an `EOF' on its
     standard input when reading a command (Note: The Set Builtin).

  7. Command history (Note: Bash History Facilities) and history
     expansion (Note: History Interaction) are enabled by default.
     Bash will save the command history to the file named by `$HISTFILE'
     when an interactive shell exits.

  8. Alias expansion (Note: Aliases) is performed by default.

  9. In the absence of any traps, Bash ignores `SIGTERM' (Note:
     Signals).

 10. In the absence of any traps, `SIGINT' is caught and handled
     ((Note: Signals).  `SIGINT' will interrupt some shell builtins.

 11. An interactive login shell sends a `SIGHUP' to all jobs on exit if
     the `hupoxexit' shell option has been enabled (Note: Signals).

 12. The `-n' invocation option is ignored, and `set -n' has no effect
     (Note: The Set Builtin).

 13. Bash will check for mail periodically, depending on the values of
     the `MAIL', `MAILPATH', and `MAILCHECK' shell variables (Note:
     Bash Variables).

 14. Expansion errors due to references to unbound shell variables after
     `set -u' has been enabled will not cause the shell to exit (Note:
     The Set Builtin).

 15. The shell will not exit on expansion errors caused by VAR being
     unset or null in `${VAR:?WORD}' expansions (Note: Shell Parameter
     Expansion).

 16. Redirection errors encountered by shell builtins will not cause the
     shell to exit.

 17. When running in POSIX mode, a special builtin returning an error
     status will not cause the shell to exit (Note: Bash POSIX Mode).

 18. A failed `exec' will not cause the shell to exit (Note: Bourne
     Shell Builtins).

 19. Parser syntax errors will not cause the shell to exit.

 20. Simple spelling correction for directory arguments to the `cd'
     builtin is enabled by default (see the description of the `cdspell'
     option to the `shopt' builtin in Note: Bash Builtins).

 21. The shell will check the value of the `TMOUT' variable and exit if
     a command is not read within the specified number of seconds after
     printing `$PS1' (Note: Bash Variables).