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打包成Deb

四大维护脚本

定义

preinst，软件安装前执行的脚本。在从deb文件中解压缩它所属的包之前执行此脚本。许多preinst脚本停止正在升级的包的服务，直到它们的安装或升级完成。
postinst，软件安装后执行的脚本。一旦app从它的deb文件中解包，这个脚本通常会完成包foo安装完成后的必需配置工作。通常，postinst脚本会要求用户输入，或警告用户，如果他们接受默认值，他们应该记得返回并根据需要重新配置该包。一旦安装或升级了新包，许多postinst脚本就会执行脚本内的命令来启动或重启服务。
prerm，软件卸载前执行的脚本。此脚本通常会停止与包关联的任何守护进程，它在卸载软件包的相关文件前执行。
postrm，软件卸载后执行的脚本。这个脚本通常修改与app相关的链接或其他文件，或删除由包创建的文件。

*.preinst，*.postinst，*.prerm，*.postrm这四类文件被称为维护者脚本，这些脚本被放置在Debian目录下的控制区内，并且被dpkg用来控制安装，升级和删除。

位置

这些维护者脚本都可以在/var/lib/dpkg/info/目录下被找到。

执行顺序

首次安装应用，dpkg -i xxxxxxx.deb，执行顺序是preinst --> postinst。
卸载并保留配置，dpkg -r xxxxxxx，执行顺序是prerm --> postrm。
卸载不保留配置，dpkg -P xxxxxxx，执行顺序是prerm --> postrm --> postrm，第一次执行postrm传入的$1为remove; 第二次执行postrm传入的$1为purge。
升级安装，dpkg -i xxxxxxx_v2.deb,，执行顺序是prerm --> preinst --> postrm --> postinst。

测试顺序

如果可能，安装前一个版本的软件包。
从前一个版本升级软件包。
降级软件包到前一个版本(可选)。
彻底删除该软件包。
全新安装该软件包。
卸载该软件包。
再次安装该软件包。
彻底删除该软件包。

举个例子

cd /var/lib/dpkg/info && ls | grep 'postinst'

随便看几个

软件安装后执行的脚本(libpam-runtime.postinst)

#!/bin/sh -e

. /usr/share/debconf/confmodule

calculate_md5sum()
{
        configfile="$1"
        sed -n -e'1,/# here are the per-package modules (the "Primary" block)/p;
                  /# here.s the fallback if no module succeeds/,/# and here are more per-package modules (the "Additional" block)/p;
                  /# end of pam-auth-update config/,$p' \
            /etc/pam.d/"$configfile" | md5sum | awk '{ print $1 }'
}

# If the user has removed the config file, respect this sign of dementia
# -- only create on package install.
force=
if [ -z "$2" ] || dpkg --compare-versions "$2" lt 1.0.1-11
then
        force=--force
        for configfile in common-auth common-account common-session  \
            common-password
        do
                if [ -f /etc/pam.d/$configfile ] && \
                    ! fgrep -q $(calculate_md5sum $configfile) \
                    /usr/share/pam/$configfile.md5sums 2>/dev/null
                then
                        force=
                fi
        done
fi

pam-auth-update --root "$DPKG_ROOT" --package $force

if [ -n "$force" ]; then
        rm -f /etc/pam.d/common-auth.pam-old \
              /etc/pam.d/common-account.pam-old \
              /etc/pam.d/common-password.pam-old \
              /etc/pam.d/common-session.pam-old
elif dpkg --compare-versions "$2" lt-nl 1.1.0-1 \
        && [ ! -e /etc/pam.d/common-session-noninteractive ]
then
        cp -a /etc/pam.d/common-session /etc/pam.d/common-session-noninteractive
fi

软件卸载前执行的脚本(libpam-runtime.prerm)

#!/bin/sh

set -e
# Packages including pam configurations need to include a block like
# the following to arrange for removal of the PAM profile prior to
# package removale.  Libpam-runtime is special because it includes the
# machinery for managing the profiles and because there is a check to
# make sure at least one profile is enabled.  Libpam-runtime can only
# be removed in a situation where dpkg checks are being overriden; in
# that case the resulting PAM config is likely to be broken anyway.
# But we prefer to permit the removal if enough dpkg force options are
# given than to create an infinite loop.  So, this block is commented
# out, left here as an example for other packages.


# if [ "$1" = remove ] ; then
#       pam-auth-update --package --remove unix
# fi

软件卸载后执行的脚本(libpam-runtime.postrm)

#!/bin/sh -e

if [ "$1" = "purge" ]; then
        rm -f /etc/pam.d/common-auth /etc/pam.d/common-account \
              /etc/pam.d/common-session /etc/pam.d/common-password \
              /etc/pam.d/common-session-noninteractive
        rm -f /var/lib/pam/auth /var/lib/pam/account /var/lib/pam/session \
              /var/lib/pam/password /var/lib/pam/seen \
              /var/lib/pam/session-noninteractive
        rmdir --ignore-fail-on-non-empty /var/lib/pam ||true
fi

# Automatically added by dh_installdebconf/13.6ubuntu1
if [ "$1" = purge ] && [ -e /usr/share/debconf/confmodule ]; then
        . /usr/share/debconf/confmodule
        db_purge
fi
# End automatically added section