Check if an apt-get package is installed and then install it if it s not on Linux

Question

I m working on a Ubuntu system and currently this is what I m doing   if   which command  gt   dev null  then    echo -e  Command not found  Install   y n   c     read    if   REPLY     y   then       sudo apt-get install command    fi fi   Is this what most people would do  Or is there a more elegant solution

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This one-liner returns 1  installed  or 0  not installed  for the  nano  package      dpkg-query -W -f    Status   nano 2 gt  dev null   grep -c  ok installed     even if the package does not exist   is not available   The example below installs the  nano  package if it is not installed    if     dpkg-query -W -f    Status   nano 2 gt  dev null   grep -c  ok installed   -eq 0    then   apt-get install nano  fi

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I offer this update since Ubuntu added its  Personal Package Archive   PPA  just as this question was answered  and PPA packages have a different result    Native Debian repository package not installed      dpkg-query -l apache-perl    echo    1  PPA package registered on host and installed      dpkg-query -l libreoffice    echo    0  PPA package registered on host but not installed      dpkg-query -l domy-ce    echo    0    sudo apt-get remove domy-ce  sudo  password for user   Reading package lists    Done Building dependency tree        Reading state information    Done Package domy-ce is not installed  so not removed 0 upgraded  0 newly installed  0 to remove and 0 not upgraded     Also posted on  https   superuser com questions 427318 test-if-a-package-is-installed-in-apt 427898

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To be a little more explicit  here s a bit of bash script that checks for a package and installs it if required  Of course  you can do other things upon finding that the package is missing  such as simply exiting with an error code   REQUIRED PKG  some-package  PKG OK   dpkg-query -W --showformat    Status  n   REQUIRED PKG grep  install ok installed   echo Checking for  REQUIRED PKG   PKG OK if          PKG OK     then   echo  No  REQUIRED PKG  Setting up  REQUIRED PKG     sudo apt-get --yes install  REQUIRED PKG  fi   If the script runs within a GUI  e g  it is a Nautilus script   you ll probably want to replace the  sudo  invocation with a  gksudo  one

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UpAndAdam wrote      However you can t simply rely on return codes here for scripting   In my experience you can rely on dkpg s exit codes   The return code of dpkg -s is 0 if the package is installed and 1 if it s not  so the simplest solution I found was   dpkg -s  lt pkg-name gt  2 gt  dev null  gt  dev null    sudo apt-get -y install  lt pkg-name gt    Works fine for me

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Use   apt-cache policy  lt package name gt    If it is not installed  it will show   Installed  none   Otherwise it will show   Installed  version

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I ve found all solutions above can produce a false positive if a package is installed and then removed yet the installation package remains on the system   To replicate  Install package apt-get install curl Remove package apt-get remove curl  Now test above answers   The following command seems to solve this condition  dpkg-query -W -f    Status  n  curl   head -n1   awk   print  3      grep -q   installed    This will result in a definitive installed or not-installed

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which  lt command gt  if         1    then      lt pkg-manager gt  -y install  lt command gt  fi

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name  rsync      which  name       echo   name   installed     sudo apt-get install -y  name

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I ve settled on one based on Nultyi s answer   MISSING   dpkg --get-selections  PACKAGES 2 gt  amp 1   grep -v  install     awk    print  6       Optional check here to skip bothering with apt-get if  MISSING is empty sudo apt-get install  MISSING   Basically  the error message from dpkg --get-selections is far easier to parse than most of the others  because it doesn t include statuses like  deinstall    It also can check multiple packages simultaneously  something you can t do with just error codes   Explanation example     dpkg --get-selections  python3-venv python3-dev screen build-essential jq dpkg  no packages found matching python3-venv dpkg  no packages found matching python3-dev screen                                          install build-essential                                 install dpkg  no packages found matching jq   So grep removes installed packages from the list  and awk pulls the package names out from the error message  resulting in MISSING  python3-venv python3-dev jq   which can be trivially inserted into an install command   I m not blindly issuing an apt-get install  PACKAGES because as mentioned in the comments  this can unexpectedly upgrade packages you weren t planning on  not really a good idea for automated processes that are expected to be stable

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This feature already exists in Ubuntu and Debian  in the command-not-found package

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This will do it  apt-get install is idempotent   sudo apt-get install command

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This seems to work pretty well     sudo dpkg-query -l   grep  lt some package name gt    wc -l    It either returns 0 if not installed or some number  gt  0 if installed

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To check if packagename was installed  type   dpkg -s  lt packagename gt    You can also use dpkg-query that has a neater output for your purpose  and accepts wild cards  too   dpkg-query -l  lt packagename gt    To find what package owns the command  try   dpkg -S  which  lt command gt     For further details  see article Find out if package is installed in Linux and dpkg cheat sheet

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In Bash   PKG  emacs  dpkg-query -l  PKG  gt   dev null    sudo apt install  PKG   Note that you can have a string with several packages in PKG

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This explicitly prints 0 if installed else 1 using only awk  dpkg-query -W -f    Status  n   PKG  2 gt  amp 1 awk   ok installed  print 0 exit  print 1    or if you prefer the other way around where 1 means installed and 0 otherwise  dpkg-query -W -f    Status  n   PKG  2 gt  amp 1 awk   ok installed  print 1 exit  print 0       replace PKG with your package name Convenience function  installed         return   dpkg-query -W -f    Status  n   quot   1  quot  2 gt  amp 1 awk   ok installed  print 0 exit  print 1          usage  installed gcc  amp  amp  echo Yes    echo No   or  if installed gcc  then     echo yes else     echo no fi

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inspired by Chris above     bin bash  installed         return   dpkg-query -W -f    Status  n   quot   1  quot  2 gt  amp 1 awk   ok installed  print 0 exit  print 1       pkgs  libgl1-mesa-dev xorg-dev vulkan-tools libvulkan-dev vulkan-validationlayers-dev spirv-tools  missing pkgs  quot  quot   for pkg in   pkgs      do     if     installed  pkg    then         missing pkgs   quot   pkg quot      fi done  if     -z  quot  missing pkgs quot     then     cmd  quot sudo apt install -y  missing pkgs quot      echo  cmd fi

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I use the following way    which mySQL 2 gt  amp 1 tee 1 gt   dev null   if            0     then                 echo -e   e 42m MySQL already installed  Moving on    e 0m          else         sudo apt-get install -y mysql-server                 if            0     then                         echo -e   e 42mMy SQL installed e 0m                  else                         echo -e   e 42Installation failed e 0m                  fi         fi

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I had a similar requirement when running test locally instead of in docker  Basically I only wanted to install any  deb files found if they weren t already installed      If there are  deb files in the folder  then install them if    ls -1   deb 2 gt   dev null   wc -l  -gt 0    then   for file in   deb  do       Only install if not already installed  non-zero exit code      dpkg -I   file    grep Package    sed -r  s  Package  s       1 g    xargs dpkg -s     if         0    then         dpkg -i   file      fi    done  else   err  No  deb files found in   PWD   fi   I guess they only problem I can see is that it doesn t check the version number of the package so if  deb file is a newer version  then this wouldn t overwrite the currently installed package

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For Ubuntu  apt provides a fairly decent way to do this  Below is an example for google chrome   apt -qq list google-chrome-stable 2 gt  dev null   grep -qE   installed upgradeable      apt-get install google-chrome-stable  I m redirecting error output to null because apt warns against using its  unstable cli   I suspect list package is stable so I think it s ok to throw this warning away  The -qq makes apt super quiet

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Many things has been told but for me simplest way is   dpkg -l   grep packagename

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dpkg-query --showformat    db Status-Status   This produces a small output string which is unlikely to change and is easy to compare deterministically without grep  pkg hello status  quot   dpkg-query -W --showformat    db Status-Status    quot  pkg quot  2 gt  amp 1  quot  if          0           quot  status quot    installed    then   sudo apt install  pkg fi  The      0 check is needed because if you ve never installed a package before  and after you remove certain packages such as hello  dpkg-query exits with status 1 and outputs to stderr  dpkg-query  no packages found matching hello  instead of outputting not-installed  The 2 gt  amp 1 captures that error message too when it comes preventing it from going to the terminal  For multiple packages  pkgs  hello certbot  install false for pkg in  pkgs  do   status  quot   dpkg-query -W --showformat    db Status-Status    quot  pkg quot  2 gt  amp 1  quot    if          0           quot  status quot    installed    then     install true     break   fi done if  quot  install quot   then   sudo apt install  pkgs fi  The possible statuses are documented in man dpkg-query as     n   Not-installed    c   Config-files    H   Half-installed    U   Unpacked    F   Half-configured    W   Triggers-awaiting    t   Triggers-pending    i   Installed  The single letter versions are obtainable with db Status-Abbrev  but they come together with the action and error status  so you get 3 characters and would need to cut it  So I think it is reliable enough to rely on the uncapitalized statuses  Config-files vs config-files  not changing instead  dpkg -s exit status This unfortunately doesn t do what most users want  pkgs  qemu-user pandoc  if   dpkg -s  pkgs  gt  dev null 2 gt  amp 1  then   sudo apt-get install  pkgs fi  because for some packages  e g  certbot  doing  sudo apt install certbot sudo apt remove certbot  leaves certbot in state config-files  which means that config files were left in the machine  And in that state  dpkg -s still returns 0  because the package metadata is still kept around so that those config files can be handled more nicely  To actually make dpkg -s return 1 as desired  --purge would be needed  sudo apt remove --purge certbot  which actually moves it into not-installed dpkg-query  no packages found matching  Note that only certain packages leave config files behind  A simpler package like hello goes directly from installed to not-installed without --purge  Tested on Ubuntu 20 10  Python apt package There is a pre-installed Python 3 package called apt in Ubuntu 18 04 which exposes an Python apt interface  A script that checks if a package is installed and installs it if not can be seen at  How to install a package using the python-apt API Here is a copy for reference     usr bin env python   aptinstall py  import apt import sys  pkg name    quot libjs-yui-doc quot   cache   apt cache Cache   cache update   cache open    pkg   cache pkg name  if pkg is installed      print  quot  pkg name  already installed quot  format pkg name pkg name  else      pkg mark install        try          cache commit       except Exception  arg          print  gt  gt  sys stderr   quot Sorry  package installation failed   err   quot  format err str arg    Check if an executable is in PATH instead See  How can I check if a program exists from a Bash script  See also  https   askubuntu com questions 165951 dpkg-get-selections-shows-packages-marked-deinstall https   askubuntu com questions 423355 how-do-i-check-if-a-package-is-installed-on-my-server

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apt list  packagename    seems to be the simplest way to do it outside of dpkg and older apt-  tools

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It seems that nowadays apt-get has an option --no-upgrade that just does what the OP wants      --no-upgrade Do not upgrade packages  When used in conjunction with install  no-upgrade will prevent packages listed from being upgraded if they are already installed     Manpage from https   linux die net man 8 apt-get  Therefore you can use  apt-get install --no-upgrade package   and package will be installed only if it s not

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This command is the most memorable   dpkg --get-selections  lt package-name gt    If it s installed it prints       lt package-name  install   Otherwise it prints     No packages found matching  lt package-name     This was tested on Ubuntu 12 04 1  Precise Pangolin

[bash] Check if an apt-get package is installed and then install it if it's not on Linux

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