nixpkgs/nixos/modules/installer/tools/nixos-enter.sh
Graham Christensen 2d42fc240c
nixos-enter: redirect to fd2 instead of a file named /dev/stderr
In some cases, /dev/stderr may not point to a sensible location. For
example, running nixos-enter inside a systemd unit where the unit's
StandardOutput and StandardError are set to be sockets. In these
cases, this line would fail.

Piping to fd2 directly works just as well, even under strange and
twisted executions.

Co-authored-by: Michael Bishop <michael.bishop@iohk.io>
2020-02-12 21:18:27 -05:00

75 lines
1.8 KiB
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#! @shell@
set -e
# Re-exec ourselves in a private mount namespace so that our bind
# mounts get cleaned up automatically.
if [ -z "$NIXOS_ENTER_REEXEC" ]; then
export NIXOS_ENTER_REEXEC=1
if [ "$(id -u)" != 0 ]; then
extraFlags="-r"
fi
exec unshare --fork --mount --uts --mount-proc --pid $extraFlags -- "$0" "$@"
else
mount --make-rprivate /
fi
mountPoint=/mnt
system=/nix/var/nix/profiles/system
command=("$system/sw/bin/bash" "--login")
silent=0
while [ "$#" -gt 0 ]; do
i="$1"; shift 1
case "$i" in
--root)
mountPoint="$1"; shift 1
;;
--system)
system="$1"; shift 1
;;
--help)
exec man nixos-enter
exit 1
;;
--command|-c)
command=("$system/sw/bin/bash" "-c" "$1")
shift 1
;;
--silent)
silent=1
;;
--)
command=("$@")
break
;;
*)
echo "$0: unknown option \`$i'"
exit 1
;;
esac
done
if [[ ! -e $mountPoint/etc/NIXOS ]]; then
echo "$0: '$mountPoint' is not a NixOS installation" >&2
exit 126
fi
mkdir -p "$mountPoint/dev" "$mountPoint/sys"
chmod 0755 "$mountPoint/dev" "$mountPoint/sys"
mount --rbind /dev "$mountPoint/dev"
mount --rbind /sys "$mountPoint/sys"
(
# If silent, write both stdout and stderr of activation script to /dev/null
# otherwise, write both streams to stderr of this process
if [ "$silent" -eq 1 ]; then
exec 2>/dev/null
fi
# Run the activation script. Set $LOCALE_ARCHIVE to supress some Perl locale warnings.
LOCALE_ARCHIVE="$system/sw/lib/locale/locale-archive" chroot "$mountPoint" "$system/activate" 1>&2 || true
)
exec chroot "$mountPoint" "${command[@]}"