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The name of the files installed by binary packages in the system PATH (namely /bin, /sbin, /usr/bin, /usr/sbin and /usr/games) must be encoded in ASCII.
The name of the files and directories installed by binary packages outside the system PATH must be encoded in UTF-8 and should be restricted to ASCII when it is possible to do so.
If you are using GCC, -fPIC produces code with relocatable position independent code, which is required for most architectures to create a shared library, with i386 and perhaps some others where non position independent code is permitted in a shared library.
Position independent code may have a performance penalty, especially on i386. However, in most cases the speed penalty must be measured against the memory wasted on the few architectures where non position independent code is even possible.
Some of the reasons why this might be required is if the library contains hand crafted assembly code that is not relocatable, the speed penalty is excessive for compute intensive libs, and similar reasons.
Some of the reasons for linking static libraries with the -fPIC flag are if, for example, one needs a Perl API for a library that is under rapid development, and has an unstable API, so shared libraries are pointless at this phase of the library’s development. In that case, since Perl needs a library with relocatable code, it may make sense to create a static library with relocatable code. Another reason cited is if you are distilling various libraries into a common shared library, like mklibs does in the Debian installer project.
You might want to replace --strip-unneeded with --strip-debug for static libraries, as dh_strip does. When stripping static libraries, you should also pass --enable-deterministic-archives to ensure that your package build is reproducible.
A common example are the so-called “plug-ins”, internal shared objects that are dynamically loaded by programs using dlopen(3).
These files store, among other things, all libraries on which that shared library depends. Unfortunately, if the .la file is present and contains that dependency information, using libtool when linking against that library will cause the resulting program or library to be linked against those dependencies as well, even if this is unnecessary. This can create unneeded dependencies on shared library packages that would otherwise be hidden behind the library ABI, and can make library transitions to new SONAMEs unnecessarily complicated and difficult to manage.
The Open Group Base Specifications Issue 7, 2018 Edition, which is also known as POSIX.1-2017 and as IEEE Std 1003.1-2017 and is available on the World Wide Web from The Open Group.
These features are in widespread use in the Linux community and are implemented in all of bash, dash, and ksh, the most common shells users may wish to use as /bin/sh.
This is necessary to allow top-level directories to be symlinks. If linking /var/run to /run were done with the relative symbolic link ../run, but /var were a symbolic link to /srv/disk1, the symbolic link would point to /srv/run rather than the intended target.
It’s better to use mkfifo rather than mknod to create named pipes to avoid false positives from automated checks for packages incorrectly creating device files.
The dpkg-maintscript-helper tool, available from the dpkg package, can help for this task.
Rationale: There are two problems with hard links. The first is that some editors break the link while editing one of the files, so that the two files may unwittingly become unlinked and different. The second is that dpkg might break the hard link while upgrading conffiles.
The traditional approach to log files has been to set up ad hoc log rotation schemes using simple shell scripts and cron. While this approach is highly customizable, it requires quite a lot of sysadmin work. Even though the original Debian system helped a little by automatically installing a system which can be used as a template, this was deemed not enough.
The use of logrotate, a program developed by Red Hat, is better, as it centralizes log management. It has both a configuration file (/etc/logrotate.conf) and a directory where packages can drop their individual log rotation configurations (/etc/logrotate.d).
When a package is upgraded, and the owner or permissions of a file included in the package has changed, dpkg arranges for the ownership and permissions to be correctly set upon installation. However, this does not extend to directories; the permissions and ownership of directories already on the system does not change on install or upgrade of packages. This makes sense, since otherwise common directories like /usr would always be in flux. To correctly change permissions of a directory the package owns, explicit action is required, usually in the postinst script. Care must be taken to handle downgrades as well, in that case.
Ordinary files installed by dpkg (as opposed to conffiles and other similar objects) normally have their permissions reset to the distributed permissions when the package is reinstalled. However, the use of dpkg-statoverride overrides this default behavior.
