--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/debian-apt.rst	Tue Jul 03 00:00:57 2012 +0300
@@ -0,0 +1,102 @@
+.. -*- coding: utf-8; -*-
+
+======
+ Apt.
+======
+
+Conf files.
+===========
+
+See man sources.list(5), apt.conf(5)::
+
+  /etc/apt/sources.list
+  /etc/apt/apt.conf
+
+Setup backport.
+===============
+
+Main backports archive you can find on www.backports.org.
+
+To get packeges gpg sign key::
+
+  $ su
+  ...
+  $ wget -O - http://backports.org/debian/archive.key | apt-key add -
+  $ ^D
+
+Write where packeges places::
+
+  $ cat /etc/apt/sources.list
+  deb cdrom:[Debian GNU/Linux 4.0 r0 _Etch_ - Official amd64 DVD Binary-2 20070407-12:15]/ etch contrib main
+  deb cdrom:[Debian GNU/Linux 4.0 r0 _Etch_ - Official amd64 DVD Binary-1 20070407-12:15]/ etch contrib main
+
+  deb http://www.backports.org/debian/ etch-backports main contrib non-free
+
+Getting new keys for packages.
+==============================
+::
+
+  $ sudo apt-get update
+  ...
+  W: There is no public key available for the following key IDs:
+  9AA38DCD55BE302B
+  W: GPG error: http://http.us.debian.org etch Release: The following signatures
+  couldn't be verified because the public key is not available: NO_PUBKEY
+  9AA38DCD55BE302B
+  ...
+
+  $ gpg --keyserver pgp.mit.edu --recv-key 9AA38DCD55BE302B \
+  --keyserver-options http-proxy=http://user:pass@192.168.1.1:3128
+  gpg: requesting key 55BE302B from hkp server pgp.mit.edu
+  gpg: key 55BE302B: public key "Debian Archive Automatic Signing Key (5.0/lenny) <ftpmaster@debian.org>" imported
+  gpg: no ultimately trusted keys found
+  gpg: Total number processed: 1
+  gpg:               imported: 1  (RSA: 1)
+
+  $ gpg --export 9AA38DCD55BE302B | sudo apt-key add -
+  OK
+
+Install build dependency for package.
+=====================================
+::
+
+  $ apt-get install build-essential    # install dev LIBC and GCC C/C++
+  $ sudo apt-get build-dep $package
+
+If all you want is checking what packages are needed to build a given package::
+
+  $ apt-cache showsrc $package
+
+or check 'Build-Depends' attribute in::
+
+  $ apt-cache show $package
+
+Delete config file for removed packages.
+========================================
+
+To get list of such packages use one of::
+
+  $ aptitude search ~c
+  $ grep-status -n -sPackage -FStatus config-files
+
+To remove them::
+
+  $ aptitude purge ~c
+
+Delete obsolete packages.
+=========================
+
+To get list of such packages use::
+
+  $ aptitude search ~o
+
+To remove them::
+
+  $ aptitude purge ~o
+
+Check package files for modification.
+=====================================
+::
+
+  $ sudo debsums --changed
+