how to search whether a software is installed?

[bsmile]

which command should I use? Can give an explicit example or links to specific examples? Thanks,

[rokytnji]

In Debian or Ubuntu

@biker:~$ apt-cache policy fluxbox
fluxbox:
  Installed: 1.3.2-2
  Candidate: 1.3.2-2
  Version table:
 *** 1.3.2-2 0
        901 http://ftp.us.debian.org/debian/ testing/main i386 Packages
        100 /var/lib/dpkg/status

or look in synaptic package manager. You did not mention what distro you are using by the way.

[oz]

which command should I use? Can give an explicit example or links to specific examples?

Hello

You didn't give any info about which distribution or package tool you've been using, so it will be hard for anyone to answer your question precisely. Can you provide more information?

[bsmile]

Thanks for your quick response. Really a newbie here .... linux distribution is CentOS, but general methods to other distribution can also be tried here

[oz]

For the Red Hat derivatives such as CentOS, you can try the following commands:

rpm -qa | grep package_name*
yum list installed package_name

...or to see all packages:

rpm -qa
yum list installed

One or more of those should work for you. Run man yum or man rpm for more details on using the commands.

Which package are you trying to determine if it's installed?

[bsmile]

For the Red Hat derivatives such as CentOS, you can try the following commands:

rpm -qa | grep package_name*
yum list installed package_name

...or to see all packages:

rpm -qa
yum list installed

One or more of those should work for you. Run man yum or man rpm for more details on using the commands.

Which package are you trying to determine if it's installed?

Thanks, very helpful. I did find out that the needed package is installed, but the problem is now how to find where it is located. The package of interest to me is libjpeg.x86_64

[Irithori]

rpm -qvl libjpeg

You can also define the details you want to see
e.g:

rpm -q --queryformat "%{NAME} %{SIZE}\n" libjpeg

This is just an example, there are a lot more tags:
rpm: Query formats

[bsmile]

Thanks for all your response. I should have googled on my last question first. But here is something I cannot find answers online. I need to locate a specific file --- jpeglib.h (the former are just efforts to locate this file, but failed). I tried "find -name jpeglib.h" but it does not work as it does not get permission to access many locations. So, is there any linux command which could help me to find out possible existence and access the location of this file without triggering alarm on permission stuff? This file should be common library to be related to jpeg graph format, thus accessing this file is fully legal, but I guess that the stupid adminstrator just made find not work here.

[Irithori]

Here is the deal:
Take back the "stupid administrator"
and I tell you where that file is, how to find, how to get it, and why the admin did not "...just made find not work here."

[bsmile]

good joking, but does hint me a way out. I have shooted the administrator an email and see how he respond. He is terribly busy, but I think he can locate the file instantly if he gets on doing it.