At our university we can get almost any ubuntu package installed we want, but we are not superusers ourselves (we need to request packages being installed).
With some libraries it is not always easy to know whether the package is already installed or not. Is there a simple way/command to check this?
I always just use this from the command line:
dpkg -l | grep mysql
so the above asks dpkg to list all the installed packages and then I grep for only those that have mysql in the name.
One more variant, using aptitude this time:
aptitude show <package>
Tab completion works here as well.
dpkg-query --showformat='${db:Status-Status}'
This produces a small output string which is unlikely to change and is easy to compare deterministically without grep:
pkg=hello
status="$(dpkg-query -W --showformat='${db:Status-Status}' "$pkg" 2>&1)"
if [ ! $? = 0 ] || [ ! "$status" = 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>&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 $pkgs; do
status="$(dpkg-query -W --showformat='${db:Status-Status}' "$pkg" 2>&1)"
if [ ! $? = 0 ] || [ ! "$status" = installed ]; then
install=true
break
fi
done
if "$install"; 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 >/dev/null 2>&1; then
sudo apt-get install $pkgs
fi
because for some packages, e.g. certbot, doing:
sudo apt install certbot
sudo apt remove certbot
leaves certbot in state config-files, which means that config files were left in the machine. And in that state, dpkg -s still returns 0, because the package metadata is still kept around so that those config files can be handled more nicely.
To actually make dpkg -s return 1 as desired, --purge would be needed:
sudo apt remove --purge certbot
which actually moves it into not-installed/dpkg-query: no packages found matching.
Note that only certain packages leave config files behind. A simpler package like hello goes directly from installed to not-installed without --purge.
Tested on Ubuntu 20.10.
Python apt package
There is a pre-installed Python 3 package called apt in Ubuntu 18.04 which exposes an Python apt interface!
A script that checks if a package is installed and installs it if not can be seen at: https://stackoverflow.com/questions/17537390/how-to-install-a-package-using-the-python-apt-api/17538002#17538002
Here is a copy for reference:
#!/usr/bin/env python
# aptinstall.py
import apt
import sys
pkg_name = "libjs-yui-doc"
cache = apt.cache.Cache()
cache.update()
cache.open()
pkg = cache[pkg_name]
if pkg.is_installed:
print "{pkg_name} already installed".format(pkg_name=pkg_name)
else:
pkg.mark_install()
try:
cache.commit()
except Exception, arg:
print >> sys.stderr, "Sorry, package installation failed [{err}]".format(err=str(arg))
Check if an executable is in PATH instead
See also
You can use dselect. It provides non-su read-only access.
Also, dpkg -s <package name> provides a lot of details related to a package. Eg"
userme:~$ dpkg-query -s sl
Package: sl
Status: unknown ok not-installed
Priority: optional
Section: games
You may use dpkg-query -s <package> 2>/dev/null | grep -q ^"Status: install ok installed"$ in scripts, since it returns exit code 1, if the <package> is not installed, and 0 if the <package> is installed.
Simpler solution:
There is now an apt list command that lists installed packages. You can also search for a specific package with
apt list <package>
See man apt for more information.
You need to check the status printed by dpkg -l, example :
$ dpkg -l firefox-esr vim winff
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-====================================-=======================-=======================-=============================================================================
hi firefox-esr 52.9.0esr+build2-0ubunt amd64 Safe and easy web browser from Mozilla
ii vim 2:8.1.1198-0york0~14.04 amd64 Vi IMproved - enhanced vi editor
rc winff 1.5.3-3 all graphical video and audio batch converter using ffmpeg or avconv
Here both vim and firefox-esr are installed, therefore you can type :
$ dpkg -l firefox-esr | grep -q ^.i && echo This package is installed. || echo This package is NOT installed.
This package is installed.
$ dpkg -l vim | grep -q ^.i && echo This package is installed. || echo This package is NOT installed.
This package is installed.
$ dpkg -l winff | grep -q ^.i && echo This package is installed. || echo This package is NOT installed.
This package is NOT installed.
Example to use specific value as var in shell scripts (eg test.sh)
#!/bin/sh
PACKAGE="${1}"
INSTALLED=$(dpkg -l | grep ${PACKAGE} >/dev/null && echo "yes" || echo "no")
echo "${PACKAGE} is installed ... ${INSTALLED}"
Make it executable and go start with:
test.sh openssh-server
Or do whatever you want with in your scripts
