[RevServer + Rev on Linux] Checking if you have the needed libraries

[Andre Garzia]

folks,

For those running or trying to run revolution under linux, there on trick
that help you troubleshoot library dependency problems. Go to your terminal
and into the folder that contains the executable engine for revolution be it
revserver or rev ide and run "ldd <executable file>" like this:

   ldd /home/agarzia/prog/revolution/4.5.0-dp-3/revolution

The output of this command lists the shared library used and their location,
like this example output from my ubuntu machine:

    linux-gate.so.1 =>  (0x00e3c000)
    libdl.so.2 => /lib/tls/i686/cmov/libdl.so.2 (0x007ca000)
    libX11.so.6 => /usr/lib/libX11.so.6 (0x00110000)
    libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0x00a1d000)
    libXext.so.6 => /usr/lib/libXext.so.6 (0x0037c000)
    libpthread.so.0 => /lib/tls/i686/cmov/libpthread.so.0 (0x004e6000)
    libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0x0038c000)
    /lib/ld-linux.so.2 (0x00548000)
    libxcb.so.1 => /usr/lib/libxcb.so.1 (0x00c2b000)
    libXau.so.6 => /usr/lib/libXau.so.6 (0x00ff0000)
    libXdmcp.so.6 => /usr/lib/libXdmcp.so.6 (0x00c15000)

Now, when it does not find some library like RevServer is doing on my ubuntu
machine, the output is like this:

    ldd revserver:

    linux-gate.so.1 =>  (0x00410000)
    libdl.so.2 => /lib/tls/i686/cmov/libdl.so.2 (0x00a0b000)
    libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0x007fc000)
    libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x005a8000)
    libpcre.so.0 => not found
    libpng12.so.0 => /lib/libpng12.so.0 (0x00110000)
    libjpeg.so.62 => /usr/lib/libjpeg.so.62 (0x006fe000)
    libcurl.so.4 => /usr/lib/libcurl.so.4 (0x006a1000)
    libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0x00135000)
    libz.so.1 => /lib/libz.so.1 (0x00326000)
    /lib/ld-linux.so.2 (0x0084a000)
    libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x0076e000)
    libidn.so.11 => /usr/lib/libidn.so.11 (0x00e48000)
    liblber-2.4.so.2 => /usr/lib/liblber-2.4.so.2 (0x00cbe000)
    libldap_r-2.4.so.2 => /usr/lib/libldap_r-2.4.so.2 (0x00482000)
    librt.so.1 => /lib/tls/i686/cmov/librt.so.1 (0x004e7000)
    libgssapi_krb5.so.2 => /usr/lib/libgssapi_krb5.so.2 (0x0028f000)
    libssl.so.0.9.8 => /lib/i686/cmov/libssl.so.0.9.8 (0x008ad000)
    libcrypto.so.0.9.8 => /lib/i686/cmov/libcrypto.so.0.9.8 (0x00a0f000)
    libresolv.so.2 => /lib/tls/i686/cmov/libresolv.so.2 (0x002be000)
    libsasl2.so.2 => /usr/lib/libsasl2.so.2 (0x002d2000)
    libgnutls.so.26 => /usr/lib/libgnutls.so.26 (0x0033b000)
    libpthread.so.0 => /lib/tls/i686/cmov/libpthread.so.0 (0x00965000)
    libkrb5.so.3 => /usr/lib/libkrb5.so.3 (0x004f0000)
    libk5crypto.so.3 => /usr/lib/libk5crypto.so.3 (0x002ea000)
    libcom_err.so.2 => /lib/libcom_err.so.2 (0x0030e000)
    libkrb5support.so.0 => /usr/lib/libkrb5support.so.0 (0x0079d000)
    libkeyutils.so.1 => /lib/libkeyutils.so.1 (0x00312000)
    libtasn1.so.3 => /usr/lib/libtasn1.so.3 (0x00fad000)
    libgcrypt.so.11 => /lib/libgcrypt.so.11 (0x00d9e000)
    libgpg-error.so.0 => /lib/libgpg-error.so.0 (0x009f9000)

You can see on the fourth line that it did not find libpcre which is the
Perl Regular Expression library that among other stuff gives use matchtext
and matchchunk functionalities and might be used internally as well. Now, I
used synaptic to install libpcre just now, why it is not able to find it?

Using the "locate" command, you can see where the libraries are located,
here it goes:

    locate libpcre

    /lib/libpcre.so.3
    /lib/libpcre.so.3.12.1

What we can see from that output is that revserver wants libpcre.so.0 and we
have libpcre.so.3 so what would a good unix chap do? A symlink to create an
alias pointing libpcre.so.0 to libpcre.so.3:

    sudo ln -s /lib/libpcre.so.3 /lib/libpcre.so.0

This creates the symbolic link and now:

    ldd ./revserver

    linux-gate.so.1 =>  (0x00939000)
    libdl.so.2 => /lib/tls/i686/cmov/libdl.so.2 (0x005dc000)
    libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0x00bac000)
    libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00cf5000)
    libpcre.so.0 => /lib/libpcre.so.0 (0x00e91000)
    ...

Now you see that the engine is happy and found all its required libs. Let us
create a simple revserver page named test.irev with the following content:

    <?rev

      put "hello world from revserver" && the version && the buildnumber &
cr

    ?>

Now when we run it from the terminal:

    ./revserver test.irev

    hello world from revserver 3.5.0 860

Hope this little piece here shows you that with some unix trick you can put
your engines to work. Remember Linux Administration is 50% Symlinking like
mad, 25% reading logs and 25% faith.

:D

Oh, you can do the same thing under mac os x with "otool" instead of "ldd".

Andre "I will symlink you into submission" Garzia






-- 
http://www.andregarzia.com All We Do Is Code.