Jtdcftul

I need to check if a specific package is installed on a machine from within a Bash script.

I found something like that but I don't know how use it correctly.

dpkg -l | grep "ansible" | awk '{print $2}'

if [$? -eq 0]; then

  echo OK

else

  echo FAIL

fi

I need check, if command dpkg -l | grep "ansible" | awk '{print $2}' return me word "Ansible" then echo OK, else echo FAIL.

@EDIT

I think better will be command

dpkg -l | grep "ansible" | awk '{print $2}'

so this command return me two words:

ansible

ansible_lint

How should I use this bash script? If I doing something like that:

ansible = $?

if [$? -eq 0]; then

  echo OK

else

  echo FAIL

fi

that's not work, but I'm sure I doing that wrong. How can I read result from dpkg -l | grep "ansible" | awk '{print $2}' command and if I get word "ansible" script will print OK, if not print FAIL.

You can check if the software is installed on this way:

if [ "$(dpkg -l | awk '/ansible/ {print }'|wc -l)" -ge 1 ]; then

  echo OK

else

  echo FAIL

fi

You can't use exit code because it will be from awk and in this case always be 0

If you know the exact package name, you can just ask dpkg if it's installed with

dpkg -l packagename

For example:

$ dpkg -l pulsea

dpkg-query: no packages found matching pulsea

The exit code is also 1 (fail) if a package isn't installed, you can test for that (as seen later).

$ dpkg -l pulseaudio

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

+++-==================-==============-==============-=========================

ii  pulseaudio         10.0-1+deb9u1  i386           PulseAudio sound server

Here the exit code is 0 (success), so you can do this too

$ if dpkg -l pulseaudio; then echo yes;fi

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

+++-==================-==============-==============-=========================

ii  pulseaudio         10.0-1+deb9u1  i386           PulseAudio sound server

yes

Note the trailing "yes" above. But now since you can just use the exit code, you don't really care about dpkg's output, so ignore it with an if or an && (AND list):

$ if dpkg -l pulseaudio >/dev/null; then echo yes;fi

yes



$ dpkg -l pulseaudio >/dev/null && echo yes

yes

dpkg can also match partial names, using asterisks, like

$ dpkg -l "*pulse*"

About pipes and their exit status, if you want to see if a command somewhere in a pipeline has failed you'll have to do something like examining the ${PIPESTATUS[@]}:

$ false | true

$ echo ${PIPESTATUS[@]} 

1 0

And like $?, ${PIPESTATUS[@]} changes with every command, so if you want to examine them more than once you have to save them to another variable first. In your example

ansible = $?

if [$? -eq 0]; then

$? has already changed by the if test, and it's probably 0 since assigning a variable like that almost always succeeds.