| 1 | #!/usr/bin/env bash
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| 2 | #
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| 3 | # Where does $HOME come from?
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| 4 | #
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| 5 | # Usage:
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| 6 | # ./home-var.sh <function name>
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| 7 |
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| 8 | set -o nounset
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| 9 | set -o pipefail
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| 10 | set -o errexit
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| 11 |
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| 12 | # In the bash source, it appears to be set in a login shell? But I don't seem
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| 13 | # to be able to tickle that line.
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| 14 | #
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| 15 | # in variables.c, initialize_shell_variables():
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| 16 | #
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| 17 | # if (login_shell == 1 && posixly_correct == 0)
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| 18 | # set_home_var ();
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| 19 |
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| 20 | test-bash() {
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| 21 | set +o errexit
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| 22 |
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| 23 | #local sh=bash
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| 24 | local sh=_tmp/spec-bin/bash
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| 25 |
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| 26 | local prog='echo home=$HOME'
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| 27 | env -i -- $sh -c "$prog"
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| 28 | env -i -- $sh -i -c "$prog"
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| 29 | env -i -- $sh --login -c "$prog"
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| 30 | env -i -- $sh --login -i -c "$prog"
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| 31 | env -i -- $sh --norc --login -c "$prog"
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| 32 |
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| 33 | local prog='echo HOME=; env | grep HOME'
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| 34 | # Test if exported
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| 35 | env -i -- $sh -c "$prog"
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| 36 | env -i -- $sh -i -c "$prog"
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| 37 | env -i -- $sh --login -c "$prog"
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| 38 | env -i -- $sh --login -i -c "$prog"
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| 39 | env -i -- $sh --norc --login -c "$prog"
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| 40 | }
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| 41 |
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| 42 | # ANSWER:
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| 43 |
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| 44 | # https://unix.stackexchange.com/questions/123858/is-the-home-environment-variable-always-set-on-a-linux-system
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| 45 |
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| 46 | # The POSIX specification requires the OS to set a value for $HOME
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| 47 | #
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| 48 | # HOME
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| 49 | # The system shall initialize this variable at the time of login to be a
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| 50 | # pathname of the user's home directory. See <pwd.h>.
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| 51 |
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| 52 | # https://superuser.com/questions/271925/where-is-the-home-environment-variable-set
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| 53 | #
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| 54 | # - by login on console, telnet and rlogin sessions
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| 55 | # - by sshd for SSH connections
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| 56 | # - by gdm, kdm or xdm for graphical sessions.
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| 57 | #
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| 58 | # This is annoying since the cron environment doesn't have it! But it looks
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| 59 | # like it shouldn't be fixed in the shell.
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| 60 |
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| 61 | "$@"
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