I am writing a script to install packages from .deb files, but first, I would like to check if each package is already installed. I have a config file that contains the information for the packages as hashmaps, like this:

declare -A package_a=(
[name]="utility-blah"
[ver]="1.2"
[arch]="amd64"
)
declare -A package_b=(
[name]="tool-bleh"
[ver]="3.4"
[arch]="all"
)
#and so on and so forth

My install script sources the config file, and I would like it to iterate over the packages, checking if they are installed, and installing them if they are not, like this:

source packages.config
declare -a packageList=("package_a" "package_b" "package_d")
for package in ${packageList[@]}; do
    # Check if the specific version is installed already
    if apt show ${package[name]}=${package[ver]}; then
        echo ${package[name]} ${package[ver]} is already installed.
    else
        echo Installing ${package[name]}
        sudo apt install path/to/files/${package[name]}_${package[ver]}_${package[arch]}.deb
    fi
done    

How can I have package point to the hashmap containing the information about the package and use it in the following commands?

I'm using Bash 4.4.20 on Ubuntu 18.04

CodePudding user response：

This kind of input data is better suited for JSON rather than using bash associative arrays and indirection.

Lets say you have a packages.json:

{
  "packages": [
    {
      "package": "package_a",
      "name": "utility-blah",
      "ver": "1.2",
      "arch": "amd64"
    },
    {
      "package": "package_b",
      "name": "utility-bleh",
      "ver": "3.4",
      "arch": "all"
    },
    {
      "package": "apache2",
      "name": "Apache2 http server",
      "ver": "2.4.52-1ubuntu4.1",
      "arch": "all"
    }
  ]
}

Such simple POSIX-shell script is able to process it as you need:

#! /bin/sh

# Fields are tab-delimited, records end with newline
IFS=$(printf '\t')

# Parses json input into record lines
jq -r '.packages[]|(.package   "\t"   .name   "\t"   .ver)' packages.json |

  # Iterates records, reading fields
  while read -r package name ver; do
    {
      # Query package for installed status and version
      # formatted into two fields
      dpkg-query -W --showformat='${db:Status-Abbrev}\t${Version}' "${package}" || :
    } 2>/dev/null | {

      # Reads status and installed version
      read -r status installed_ver _

      # If status is installed 'ii ' and installed version matches'
      if [ "${status}x" = 'ii x' ] && [ "${ver}x" = "${installed_ver}x" ]; then
        printf '%s %s is already installed.\n' "${name}" "${ver}"
      else
        printf 'Installing %s.\n' "${name}"
      fi
    }
  done

Example output:

nstalling utility-blah.
nstalling utility-bleh.
Apache2 http server 2.4.52-1ubuntu4.1 is already installed.

CodePudding user response：

One idea using a nameref:

source packages.config
declare -a packageList=("package_a" "package_b" "package_d")

for pkg in "${packageList[@]}"; do                                      # change variable name
    declare -n package=pkg                                            # declare nameref; rest of code remains the same ...

    # Check if the specific version is installed already
    if apt show ${package[name]}=${package[ver]}; then
        echo ${package[name]} ${package[ver]} is already installed.
    else
        echo Installing ${package[name]}
        sudo apt install path/to/files/${package[name]}_${package[ver]}_${package[arch]}.deb
    fi
done  

Or (as M. Nejat Aydin and Benjamin W. have pointed out) the declare -n can go before the while loop, eg:

declare -n package

for package in "${packageList[@]}"; do                                          
    # Check if the specific version is installed already
    if apt show ${package[name]}=${package[ver]}; then
        echo ${package[name]} ${package[ver]} is already installed.
    else
        echo Installing ${package[name]}
        sudo apt install path/to/files/${package[name]}_${package[ver]}_${package[arch]}.deb
    fi
done  

Simple test:

declare -n package

for package in ${packageList[@]}; do 
    echo "${!package} : ${package[name]}"
done

This generates:

package_a : utility-blah
package_b : tool-bleh
package_d :