.. index:: hush shell .. _hush: Hush shell ========== barebox has an integrated shell: hush. This is a simple shell which is enough for writing simple shell scripts. Usage of the shell for scripts should not be overstrained. Often a command written in C is more flexible and also more robust than a complicated shell script. Hush features ------------- variables: .. code-block:: sh a="Hello user" echo $a Hello user conditional execution ``if`` / ``elif`` / ``else`` / ``fi``: .. code-block:: sh if [ ${foo} = ${bar} ]; then echo "foo equals bar" else echo "foo and bar differ" fi ``for`` loops: .. code-block:: sh for i in a b c; do echo $i done ``while`` loops: .. code-block:: sh while true; do echo "endless loop" done wildcard globbing: .. code-block:: sh ls d* echo ??? There is no support in hush for input/output redirection or pipes. Some commands work around this limitation with additional arguments. for example the :ref:`command_echo` command has the ``-a FILE`` option for appending a file and the ``-o FILE`` option for overwriting a file. The readline command requires a variable name as argument in which the line will be stored. **NOTE:** hush feels like a normal Unix shell, but it cannot calculate by itself, i.e. $(($A/2)) won't work. Calculation can however be done with :ref:`command_let`: .. code-block:: sh A=10 let B=$A/2 echo $B