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