grep a variable within an if statement

Question

Maybe I am approaching this the wrong way, so I am open for suggestions. I am trying to avoid adding the output of INSTALLED_LIST to a file. I wish to use it within a variable.

Basically, I want to check if a list (INSTALLATION_PACKAGES) of packages are installed on a system. If not, record which ones failed to install, record the information, and exit. Outside of the if statement, this works fine (see commented out line), I am just having issues implementing it within an if statement.

Thx in advance for your help.

INSTALLED_LIST=`dpkg --list`

for i in $INSTALLTION_PACKAGES; do
  apt-get -y install $i
  # echo "$INSTALLED_LIST" | grep -ie "^ii  $i "
  if ! echo "$INSTALLED_LIST" | grep -ie "^ii  $i "  ; then
    echo $i >> $FAILED_INSTALL
  fi
done

Answer 1

If you want all packages in $INSTALLATION_PACKAGES to be installed, just apt-get install all of them and then check whether any of them failed:

apt-get -y $INSTALLATION_PACKAGES
list=$(dpkg -l | grep ^ii)
for i in $INSTALLATION_PACKAGES do
    echo "$list" | grep -w "$i" || echo "$i" >> $FAILED_INSTALL
done