Checking for installed packages and if not found install

Question

I need to check for installed packages and if not installed install them.

Example for RHEL, CentOS, Fedora:

rpm -qa | grep glibc-static
glibc-static-2.1         


        

Answer 1

if [ $(yum list installed | cut -f1 -d" " | grep --extended '^full name of package being checked$' | wc -l) -eq 1 ]; then
  echo "installed";
else
  echo "missing"
fi

I use this because it returns installed / missing without relying on an error state (which can cause problems in scripts taking a "no tolerance" approach to errors via

set -o errexit

for example)