Chapter 8. Shared libraries

59

8.6.4 Providing a

shlibs

file

If your package provides a shared library, you should create a

shlibs

file following the format

described above. It is usual to call this file

debian/shlibs

(but if you have multiple binary

packages, you might want to call it

debian/shlibs.

package

instead). Then let

debian

/rules

install it in the control area:

install  m644 debian/shlibs debian/tmp/DEBIAN

or, in the case of a multi binary package:

install  m644 debian/shlibs.

package

debian/

package

/DEBIAN/shlibs

An alternative way of doing this is to create the

shlibs

file in the control area directly from

debian/rules

without using a

debian/shlibs

file at all,

10

since the

debian/shlibs

file

itself is ignored by

dpkg shlibdeps

.

As

dpkg shlibdeps

reads the

DEBIAN/shlibs

files in all of the binary packages being

built from this source package, all of the

DEBIAN/shlibs

files should be installed before

dpkg shlibdeps

is called on any of the binary packages.

8.6.5 Writing the

debian/shlibs.local

file

This file is intended only as a temporary fix if your binaries or libraries depend on a library

whose package does not yet provide a correct

shlibs

file.

We will assume that you are trying to package a binary

foo

.

When you try running

dpkg shlibdeps

you get the following error message (

 O

displays the dependency informa 

tion on

stdout

instead of writing it to

debian/substvars

, and the lines have been wrapped

for ease of reading):

$ dpkg shlibdeps  O debian/tmp/usr/bin/foo

dpkg shlibdeps: warning: unable to find dependency

information for shared library libbar (soname 1,

path /usr/lib/libbar.so.1, dependency field Depends)

shlibs:Depends=libc6 (>= 2.2.2 2)

You can then run

ldd

on the binary to find the full location of the library concerned:

$ ldd foo

libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)

libc.so.6 => /lib/libc.so.6 (0x40032000)

/lib/ld linux.so.2 => /lib/ld linux.so.2 (0x40000000)

So the

foo

binary depends on the

libbar

shared library, but no package seems to provide

a

*.shlibs

file handling

libbar.so.1

in

/var/lib/dpkg/info/

. Let's determine the

package responsible:

10

This is what

dh_makeshlibs

in the

debhelper

suite does.