A variável DPKG_HOOK_ACTION do Dpkg env não está definida no script de gancho

Question

De acordo com man dpkg , posso usar DPKG_HOOK_ACTION para obter a ação atual do dpkg sendo executada no meu script de gancho do dpkg

--pre-invoke=command
--post-invoke=command
      Set an invoke hook command to be run via “sh -c” before or after the dpkg run for the unpack, configure, install, triggers-only, remove  and  purge  dpkg  actions.  This
      option  can be specified multiple times. The order the options are specified is preserved, with the ones from the configuration files taking precedence.  The environment
      variable DPKG_HOOK_ACTION is set for the hooks to the current dpkg action. Note: front-ends might call dpkg several times per invocation, which might run the hooks  more
      times than expected.

mas parece não funcionar neste comando de gancho. Alguma ideia do que está errado aqui?

$ cat /etc/apt/apt.conf.d/99testhook
DPkg::Pre-Invoke {"echo This is testhook. Current action is $DPKG_HOOK_ACTION; exit 0";};

$ sudo apt-get install screen
...
Fetched 628 kB in 0s (4,366 kB/s)
This is testhook. Current action is
Selecting previously unselected package screen.

    

Answer 1

Isso se aplica somente aos comandos especificados pelas opções --pre-invoke e --post-invoke , não quando os comandos são definidos na configuração.

Isso pode ser demonstrado colocando seu comando echo em um script:

# cat > /tmp/pre-invoke.sh <<'EOF'
#!/bin/sh
echo This is testhook. Current action is $DPKG_HOOK_ACTION; exit 0
EOF
# chmod +x /tmp/pre-invoke.sh
# dpkg --pre-invoke=/tmp/pre-invoke.sh -i /var/cache/apt/archives/rsync_3.1.1-2+b1_amd64.deb
This is testhook. Current action is install
(Reading database ... 113857 files and directories currently installed.)
Preparing to unpack .../rsync_3.1.1-2+b1_amd64.deb ...
Unpacking rsync (3.1.1-2+b1) over (3.1.1-2+b1) ...
Setting up rsync (3.1.1-2+b1) ...
Restarting rsync daemon: rsync.
Processing triggers for man-db (2.6.7.1-1) ...