Interactive shell

When the interactive shell option is enabled, the shell behaves in a way that is more suitable for interactive use. Currently, only the essential features are implemented, but more will be added in the future.

Enabling interactive mode

When you start the shell without arguments in a terminal, it usually enables interactive mode by default:

yash3

Specifically, interactive mode is enabled if:

• you do not specify +i,
• the -s option is active, either explicitly or implicitly, and
• standard input and standard error are terminals.

To force the shell to be interactive, use the -i option:

yash3 -i

Interactive mode can only be set at startup. To change the interactive mode, you must restart the shell.

Telling if the shell is interactive

To determine if the shell is running in interactive mode, check whether the - special parameter contains i:

case $- in
  *i*) echo "Interactive shell" ;;
  *)   echo "Non-interactive shell" ;;
esac

See Viewing current options for additional methods.

What happens in interactive mode

When the shell is interactive:

• The shell executes an rcfile during startup.
• The - special parameter includes i.
• The exec shell option is always considered set.
• The ignoreeof shell option is honored.
• Starting an asynchronous command prints its job number and process ID.
• The shell does not exit immediately on most shell errors.
• Some signals are automatically ignored.
• Signals ignored on entry can be trapped.
• Command prompts are displayed when reading input.
• Job status changes are reported before prompting for input if job control is enabled.
• The read built-in displays a prompt when reading a second or subsequent line of input.