# how to check if a library is installed?

In linux, how do I check if a library is installed or not? (from the command line of course).

In my specific case now, I want to check whether libjpeg is installed.

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What distribution are you using ? –  radius Aug 16 '09 at 16:09

To do this in a distro-independent* fashion you can use ldconfig with grep, like this:

ldconfig -p | grep libjpeg


If libjpeg is not installed, there will be no output. If it is installed, you will get a line for each version available.

Replace libjpeg by any library you want, and you have a generic, distro-independent* way of checking for library availability.

*99% of the times

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Better than locate! –  digz6666 Nov 11 '13 at 3:07
This should be accepted as the answer. Great! –  user105523 Dec 19 '13 at 13:53

You can check with the package manager of your distribution (aptitude, yum, ...) but as you did not give your distribution I can't give you the right command.

Another way can be to run gcc -ljpeg, if you get 'ld: library not found for -ljpeg' it means that gcc has not found the library (but it don't mean that it's not installed), if you get something like 'Undefined symbols: "_main", referenced from: ...' it means that libjpeg has been found.

locate libjpeg; ls /usr/lib/libjpeg*; ls /lib/libjpeg* are some other way to find if the lib in installed in the system

There is many other way to check that, if you give us more context (why you need to check if libjpeg is installed) we could give you the best solution for your specific case.

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How to find it using aptitude? –  BBK Apr 3 '12 at 5:52

I'm use whereis utility.
Sample:

l1feh4ck3r@xxx:~$whereis libjpeg libjpeg: /usr/lib/libjpeg.so /usr/lib/libjpeg.a /usr/lib/libjpeg.la - For deb-based distribution you can do dpkg -s packagename  Or if you know the filename only, use locate filename  The filename is usually libsomething.so[.version]. - The filename can also be something like "libsomething.a" for static version. – radius Aug 16 '09 at 16:40 I find dpkg -s limited in utility, because it wants the actual package name, which may differ subtly or significantly from the library itself. I use dpkg -s|grep LIBRARY – Drew Stephens Aug 16 '09 at 16:41 @dinomite apt-file is your friend :) – radius Aug 16 '09 at 16:50 This is done by configuration tools on linux all the time. Look at this Tutorial about autoconf and KDevelop. Other tricks would use commands like ldconfig and dpkg. - On Redhat based systems, one can use pkg-config to verify if a library is installed or not. Many rpm binaries actually make the same checks before proceeding with installation, so we can reasonably rely on its veracity. pkg-config --cflags jpeg pkg-config --libs jpeg pkg-config --cflags "jpeg >= 1.0.0" # for version check pkg-config --modversion jpeg | awk -F. '{ printf "0x%02X%02X%02X\n",$1,$2,$3 }' #version check

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