A Way to Print an Environment Variable from a Yocto Task

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This post shows _a_ way to print an environment variable from a Yocto task. I list it as _a_ way since I’m just learning Yocto and haven’t come across a better way to do this.

Given this Yocto snippet in a recipe (a *.bb file):

export DL_DIR
export P
export WORKDIR

python do_unpack() {
        bb.note("Unpacking source tarball ...")

        os.system("tar x -C ${WORKDIR} -f ${DL_DIR}/${P}.tar.gz")

        bb.note("Unpacked source tarball.")
}

DL_DIR = "${TOPDIR}/downloads"
P = "${PN}-${PV}"
WORKDIR = "${TMPDIR}/work/${PF}"

You can use the following to see what DL_DIR, P and WORKDIR are:

python do_unpack() {
        bb.note("Unpacking source tarball WORKDIR = ", d.getVar('WORKDIR', True), "DL_DIR = ", d.getVar('DL_DIR', True), "P = ", d.getVar('P', True), " ...")

        os.system("tar x -C ${WORKDIR} -f ${DL_DIR}/${P}.tar.gz")

        bb.note("Unpacked source tarball.")
}

References

Yocto logo from link.