[Tux]

Debian notes: doing things the "Debian Way"

I used Redhat and other RPM-based linux distros for years. When I started using Debian, I began maintaining this set of notes reminding me of some of the different ways Debian has of doing things. In many cases, I've listed the comparable Debian and Redhat commands.

See also the Debian Reference Card.

mandb -c does what makewhatis does in other distros and other Unices -- builds the whatis/apropos databases. It's part of the man-db package.

Package management

Updating and installing packages

apt-get update
Run this after changing /etc/apt/sources.list or /etc/apt/preferences. (this debianhelp.org page is helpful); run it periodically anyway, to make sure your source list is up-to-date.
apt-get dist-upgrade
Get all software updates available for this distro. (apt-get upgrade and apt-get -f dist-upgrade are other options; see this blog post for some of the differences.)
apt-get install packagename
installs a new package: rpm -i package.rpm
apt-get autoclean
Run this periodically to clean out .deb archives from packages which are no longer installed on the system. You can regain lots of disk space that way. If you're really desperate for disk space, apt-get clean is more radical, and will remove .deb files even for packages currently installed. But most of the time you probably don't need the .debs any more, so it might be worth it if you're strapped for megabytes.

Querying packages not yet installed

apt-cache search string
Searches for string in the list of known packages: like using rpmfind.
dpkg -l package-name-pattern
List packages matching pattern: rpm -q pattern or rpm -qa | grep pattern.
apt-file search filename
Search for a package (need not be installed) containing files including the string. apt-file is a package of its own, which you may have to apt-get install first, then run apt-file update. If apt-file search filename shows you too much, try apt-file search filename | grep -w filename (which shows you only the files that contain filename as a whole word) or variants like apt-file search filename | grep /bin/ only files located in directories like /bin or /usr/bin, useful if you're looking for a particular executable).
apt-cache showpkg pkgs...
Show information about packages.
apt-cache dumpavail
Prints out an available list.
apt-cache show pkgs...
Displays package records, even uninstalled ones, similar to dpkg --print-avail. Like rpm -q packagename.
apt-cache depends <package>
Show what <package> depends on.
apt-cache rdepends <package>
Show what other packages depend on <package>.
grep-excuses <package>
Show why package, in unstable, isn't in testing yet.
apt-cache pkgnames
Fast listing of every package in the system.

Querying currently installed packages

dpkg -S file
Which installed package owns the file? Like rpm -qf file.
dpkg -L package
List files in the package. Like rpm -ql package.
apt-cache policy pkg
Show which repository pkg came from, if you have multiple ones in sources.list.
apt-cache show <package> | grep ^Source
Find the source package which produces this binary package. If it returns nothing, then the source package name is the same as the binary package name.

The APT HOWTO has instructions on "pinning" and other details of maintaining a mixed debian system (e.g. stable but using some packages from unstable). It also shows how to pin a package so it will not be upgraded (for instance, if you've made local changes).

deborphan and debfoster are great for finding orphaned and unneeded packages which can be removed.

You can pull from a different repository by editing /etc/apt/sources.list to replace "stable" with "unstable" (or whatever) then doing apt-get update. That gets old, though, so here's a better way: pinning. Here's a sample unstable preferences file.

Boot time services

update-rc.d svc defaults
Enable service at boot time. chkconfig svc on
update-rc.d svc stop 0 1 2 3 4 5 6
Disable scv at boot time. This puts "K" links in all relevant runlevels, so theoretically apt-get will know to keep the service disabled, and won't re-enable it. At least in theory. In practice there's something wrong with the command and I haven't figured out how to make it work. Adding "." at the end doesn't work either.
update-rc.d -f svc remove
Disable service at boot time. chkconfig svc off This is simpler than the preceeding line, but less permanent; services will come back on an apt-get install or dist-upgrade.
-f means force removal of the /etc/rc.? scripts while leaving the basic script in /etc/init.d (so you can run the service by hand if you choose). --purge means remove the script from init.d.

If you want to remove a service so that it never starts unless asked, and never comes back in a dist-upgrade ... I still don't know. Apparently the only way is to go to each directory named /etc/rc?.d in turn, and then rename Snnservicename to Knnservicename (which you can't easily do as a script or alias because of the nns being variable). It's unbelievable that debian has no easier way to do this. Oh, well.
update-rc.d svc start 20 2 3 4 5 . stop 20 0 1 6
Enable service at boot time in the given runlevels, like chkconfig svc --levels 2345 on
For listing active services, I wrote a shell script: lsconfig
What services are currently enabled? chkconfig --list

Quick tips:

apt history: what's been recently installed?

There's no real or supported way to see your recent apt history, unfortunately. But if you sort /var/cache/apt/archives by create date, e.g. ls -ltc /var/cache/apt/archives | more you can get a list of packages in reverse order of when they were downloaded. Also, sometimes you can get useful apt install information from /var/log/apt/term.log.

Neither one helps in finding out what you've removed recently, though.

Printing

I could never get my Epson printer to work through normal cups configuration. But a new (late 2004) package called printconf auto-detects it and does the necessary magic. If you're having problems with Debian CUPS, try printconf.

If printing from mozilla doesn't work, persistently gets the page size wrong (e.g. keeps going back to A4 even though your system page size is us-letter), or prints pages twice as big as they should be (so you only see the top left quarter of the page and your printer dies horribly trying to print a 16" wide page), try stopping Xprt -- /etc/init.d/xprt stop -- and see if that helps. If so, since the next dist-upgrade will turn it back on again, I recommend just removing Xprt: apt-get --purge remove xprt xprt-common xprt-xprintorg Apt-get will tell you it's going to remove "x-window-system". Don't panic! That's just a meta-package; removing it will not remove your X server or libraries.

Speeding up USB init during boot

Debian seems to take a lot longer to get through USB during boot than Redhat on my Vaio. That turns out to be hotplug running usb.agent for the devices it finds (basically, I think, the hub and the empty memory stick reader). You can drastically speed up boot by editing /etc/hotplug/usb.rc and adding an ampersand (&) after the line that runs /etc/hotplug/usb.agent inside the loop in usb_boot_events().


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