83 lines
2.0 KiB
ReStructuredText
83 lines
2.0 KiB
ReStructuredText
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.. _posix-env-sample:
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POSIX Environment Variables
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###########################
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Overview
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********
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In this sample application, the POSIX :c:func:`setenv`, function is used to populate several environment
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variables in C. Then, all environment variables are then printed.
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If the user sets a new value for the ``ALERT`` environment variable, it is printed to standard
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output, and then cleared via :c:func:`unsetenv`.
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Building and Running
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********************
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This project outputs to the console. It can be built and executed on QEMU as follows:
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.. zephyr-app-commands::
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:zephyr-app: samples/posix/env
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:host-os: unix
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:board: qemu_riscv32
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:goals: run
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:compact:
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Sample Output
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=============
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The program below shows sample output for a specific Zephyr build.
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.. code-block:: console
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BOARD=qemu_riscv32
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BUILD_VERSION=zephyr-v3.5.0-5372-g3a46f2d052c7
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ALERT=
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Setting Environment Variables
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=============================
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The shell command below shows how to create a new environment variable or update the value
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associated with an existing environment variable.
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The C code that is part of this sample application displays the value associated with the
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``ALERT`` environment variable and then immediately unsets it.
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.. code-block:: console
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uart:~$ posix env set ALERT="Happy Friday!"
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uart:~$ ALERT="Happy Friday!"
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uart:~$ posix env set HOME="127.0.0.1"
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uart:~$
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Getting Environment Variables
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=============================
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The shell command below may be used to display the value associated with one environment variable.
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.. code-block:: console
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uart:~$ posix env get BOARD
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qemu_riscv32
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The shell command below may be used to display all environment variables and their associated
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values.
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.. code-block:: console
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uart:~$ posix env get
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BOARD=qemu_riscv32
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BUILD_VERSION=zephyr-v3.5.0-5372-g3a46f2d052c7
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ALERT=
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Unsetting Environment Variables
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===============================
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The shell command below may be used to unset environment variables.
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.. code-block:: console
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uart:~$ posix env unset BOARD
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