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Thursday·01·September·2011

Useful but Unknown Unix Tools: How wdiff and colordiff help to choose the right Swiss Army Knife //at 12:18 //by abe

from the colorful-diffs dept.

In light of the fact that it seems possible to fit the plastic caps of a Debian branded Swiss Army Knife (Last orders today!) on an existing Swiss Army Knife (German written howto as PDF), I started to think about which Victorinox Cybertool would be the best fitting for me.

And because the Victorinox comparison page doesn’t really show diffs, just columns with floating text which are not very helpful for generating diffs in your head, I used command line tools for that purpose:

wdiff

Because the floating texts are not line- but just whitespace-based, the tool of choice is not diff but wdiff, a word-based diff. It encloses additions and removals in {+…+} and [-…-] blocks. (No, those aren’t Japanese smileys although they look a lot like some. ^^).

The easiest and clearest way is to copy and paste the texts from Victorinox’ comparison page into some text files and compare them with wdiff:

$ wdiff cybertool34.txt cybertool41.txt
{+Schraubendreher 2.5mm,+} Pinzette, Nähahle mit Nadelöhr, {+Holzsäge,+} Bit-Schlüssel( 5 mm Innensechskant für die D-SUB Steckverbinder, 4 mm Innensechskant für Bits, Bit Phillips 0, Bit Phillips 1, Bit-Schlitzschrauben 4 mm, Bit Phillips 2, Bit Hex 4 mm, Bit Torx 8, Bit Torx 10, Bit Torx 15 ), Kombizange( Hülsenpresser, Drahtschneider ), Stech-Bohrahle, Kugelschreiber( auch zum DIP-Switch verstellen ), Mehrzweckhaken (Paketträger), {+Metallsäge( Metallfeile, Nagelfeile, Nagelreiniger ),+} Dosenöffner( kleiner Schraubendreher ), Kleine Klinge, Grosse Klinge, Ring, inox, Mini-Schraubendreher, Kapselheber( Schraubendreher, Drahtabisolierer ), {+Holzmeissel / Schaber,+} Bit-Halter, Stecknadel, inox, Schere, Korkenzieher, Zahnstocher

So this already extracted the information which are the seven tools which are in the Cybertool 41, but not in the Cybertool 34. Nevertheless the diff is still not easily recognizable on the first glance. There are several ways to help here.

First wdiff has an option --no-common (the according short option is -3) which just shows added and removed words:

$ wdiff -3 cybertool34.txt cybertool41.txt
======================================================================
{+Schraubendreher 2.5mm,+}
======================================================================
 {+Holzsäge,+}
======================================================================
 {+Metallsäge( Metallfeile, Nagelfeile, Nagelreiniger ),+}
======================================================================
 {+Holzmeissel / Schaber,+}
======================================================================

This is already way better to quickly recognize the actual differences.

But if you still also want to see the common tools of the two knifes you need some visual help:

One option is to use wdiff’s --terminal (or short -t) option. Added words are then displayed inverse and removed words are shown underlined (background and foreground colors hardcoded as there is no “invert colors” style in CSS or HTML):

$ wdiff -t cybertool34.txt cybertool41.txt
Schraubendreher 2.5mm, Pinzette, Nähahle mit Nadelöhr, Holzsäge, Bit-Schlüssel( 5 mm Innensechskant für die D-SUB Steckverbinder, 4 mm Innensechskant für Bits, Bit Phillips 0, Bit Phillips 1, Bit-Schlitzschrauben 4 mm, Bit Phillips 2, Bit Hex 4 mm, Bit Torx 8, Bit Torx 10, Bit Torx 15 ), Kombizange( Hülsenpresser, Drahtschneider ), Stech-Bohrahle, Kugelschreiber( auch zum DIP-Switch verstellen ), Mehrzweckhaken (Paketträger), Metallsäge( Metallfeile, Nagelfeile, Nagelreiniger ), Dosenöffner( kleiner Schraubendreher ), Kleine Klinge, Druckkugelschreiber, Grosse Klinge, Ring, inox, Mini-Schraubendreher, Kapselheber( Schraubendreher, Drahtabisolierer ), Holzmeissel / Schaber, Bit-Halter, Stecknadel, inox, Schere, Korkenzieher, Zahnstocher

But some still like to to use color instead of the contrast-rich inverse and the easily to oversee underlining. This is where colordiff comes into play:

colordiff

colordiff is like syntax highlighting for diffs on the command line. I works with classic and unified diffs as well as with wdiffs and debdiffs (the debdiff command is part of the devscripts package).

$ wdiff cybertool34.txt cybertool41.txt | colordiff
{+Schraubendreher 2.5mm,+} Pinzette, Nähahle mit Nadelöhr, {+Holzsäge,+} Bit-Schlüssel( 5 mm Innensechskant für die D-SUB Steckverbinder, 4 mm Innensechskant für Bits, Bit Phillips 0, Bit Phillips 1, Bit-Schlitzschrauben 4 mm, Bit Phillips 2, Bit Hex 4 mm, Bit Torx 8, Bit Torx 10, Bit Torx 15 ), Kombizange( Hülsenpresser, Drahtschneider ), Stech-Bohrahle, Kugelschreiber( auch zum DIP-Switch verstellen ), Mehrzweckhaken (Paketträger), {+Metallsäge( Metallfeile, Nagelfeile, Nagelreiniger ),+} Dosenöffner( kleiner Schraubendreher ), Kleine Klinge, Grosse Klinge, Ring, inox, Mini-Schraubendreher, Kapselheber( Schraubendreher, Drahtabisolierer ), {+Holzmeissel / Schaber,+} Bit-Halter, Stecknadel, inox, Schere, Korkenzieher, Zahnstocher

$ wdiff cybertool29.txt cybertool41.txt | colordiff
{+Schraubendreher 2.5mm,+} Pinzette, Nähahle mit Nadelöhr, {+Holzsäge,+} Bit-Schlüssel( 5 mm Innensechskant für die D-SUB Steckverbinder, 4 mm Innensechskant für Bits, Bit Phillips 0, Bit Phillips 1, Bit-Schlitzschrauben 4 mm, Bit Phillips 2, Bit Hex 4 mm, Bit Torx 8, Bit Torx 10, Bit Torx 15 ), {+Kombizange( Hülsenpresser, Drahtschneider ),+} Stech-Bohrahle, {+Kugelschreiber( auch zum DIP-Switch verstellen ), Mehrzweckhaken (Paketträger), Metallsäge( Metallfeile, Nagelfeile, Nagelreiniger ),+} Dosenöffner( kleiner Schraubendreher ), Kleine Klinge, [-Druckkugelschreiber,-] Grosse Klinge, Ring, inox, Mini-Schraubendreher, Kapselheber( Schraubendreher, Drahtabisolierer ), {+Holzmeissel / Schaber,+} Bit-Halter, Stecknadel, inox, {+Schere,+} Korkenzieher, Zahnstocher

(Coloured “Screenshots” done with ANSI HTML Adapter from the package aha.)

Some, especially those who are used to git, are probably confused by the default choice of diff colors. This is easily fixable by writing the following into you ~/.colordiffrc:

newtext=green
oldtext=red
diffstuff=darkblue
cvsstuff=darkyellow

(See also /etc/colordiff for the defaults and hints.)

colordiff has by the way two operating modes:

  • Without parameter it reads diffs from standard input as seen above.
  • With parameters it works as drop-in diff replacement including all diff options as shown below.

So now let us compare the Cybertool 29 with Cybertool 34 in a normal diff (by using the texts from above and replacing all commata with newline characters) with git-like colors:

$ colordiff cybertool29-lines.txt cybertool34-lines.txt
12a13,14
> Kombizange( Hülsenpresser
> Drahtschneider )
13a16,17
> Kugelschreiber( auch zum DIP-Switch verstellen )
> Mehrzweckhaken (Paketträger)
16d19
< Druckkugelschreiber
25a29
> Schere

Or as unifed diff with some context:

$ colordiff -u cybertool29-lines.txt cybertool34-lines.txt
--- cybertool29-lines.txt     2011-08-31 20:55:37.195546238 +0200
+++ cybertool34-lines.txt   2011-08-31 20:55:11.667710504 +0200
@@ -10,10 +10,13 @@
 Bit Torx 8
 Bit Torx 10
 Bit Torx 15 )
+Kombizange( Hülsenpresser
+Drahtschneider )
 Stech-Bohrahle
+Kugelschreiber( auch zum DIP-Switch verstellen )
+Mehrzweckhaken (Paketträger)
 Dosenöffner( kleiner Schraubendreher )
 Kleine Klinge
-Druckkugelschreiber
 Grosse Klinge
 Ring
 inox
@@ -23,5 +26,6 @@
 Bit-Halter
 Stecknadel
 inox
+Schere
 Korkenzieher
 Zahnstocher

So if you want nicely colored diffs with Subversion like you’re used to with git, you can use svn diff | colordiff.

Wednesday·31·August·2011

Useful but Unknown Unix Tools: Calculating with IPs, The Sequel //at 20:09 //by abe

from the juggling-with-IPv6-netmasks dept.

This is a direct followup on my previous blog posting about calculating IPs and netmasks with the tools netmask and prips. Kurt Roeckx (via e-mail) and Niall Donegan (via a comment to that blog posting) both told me about the package sipcalc, and Kurt also mentioned the package ipcalc. Thanks for that! And since I found both useful, too, let’s put them in their own blog posting:

Both tools, ipcalc and sipcalc offer a “get all information at once” mode which are not present in the previously presented tool netmask.

ipcalc

ipcalc by default outputs all information and even in ANSI colors:

$ ipcalc 192.168.96.0/21
Address:   192.168.96.0         11000000.10101000.01100 000.00000000
Netmask:   255.255.248.0 = 21   11111111.11111111.11111 000.00000000
Wildcard:  0.0.7.255            00000000.00000000.00000 111.11111111
=>
Network:   192.168.96.0/21      11000000.10101000.01100 000.00000000
HostMin:   192.168.96.1         11000000.10101000.01100 000.00000001
HostMax:   192.168.103.254      11000000.10101000.01100 111.11111110
Broadcast: 192.168.103.255      11000000.10101000.01100 111.11111111
Hosts/Net: 2046                  Class C, Private Internet

(Coloured “Screenshots” done with ANSI HTML Adapter from the package aha.)

You can suppress the bitwise option or directly output HTML via commandline options. For example ipcalc -b -h 192.168.96.0/21 outputs the following content:

Address:     192.168.96.0         
Netmask: 255.255.248.0 = 21
Wildcard: 0.0.7.255
=>
Network:     192.168.96.0/21      
HostMin: 192.168.96.1
HostMax: 192.168.103.254
Broadcast: 192.168.103.255
Hosts/Net: 2046 Class C, Private Internet

Yes, that’s an HTML table and no preformatted text, just with a monospaced font. (I just removed the hardcoded text color from it, otherwise it would not look nice on dark backgrounds like in Planet Commandline’s default color scheme.)

Like netmask, ipcalc can also deaggregate IP ranges into largest possible networks:

$ ipcalc 192.168.87.0 - 192.168.110.255
deaggregate 192.168.87.0 - 192.168.110.255
192.168.87.0/24
192.168.88.0/21
192.168.96.0/21
192.168.104.0/22
192.168.108.0/23
192.168.110.0/24

(ipcalc -r 192.168.87.0 192.168.110.255 is just another way to write this, and it results in the same output.)

To find networks with at least 20, 63 and 30 IP addresses within a /24 network, use for example:

Address:   192.0.2.0            
Netmask:   255.255.255.0 = 24   
Wildcard:  0.0.0.255            
=>
Network:   192.0.2.0/24         
HostMin:   192.0.2.1            
HostMax:   192.0.2.254          
Broadcast: 192.0.2.255          
Hosts/Net: 254                   Class C

1. Requested size: 20 hosts
Netmask:   255.255.255.224 = 27 
Network:   192.0.2.128/27       
HostMin:   192.0.2.129          
HostMax:   192.0.2.158          
Broadcast: 192.0.2.159          
Hosts/Net: 30                    Class C

2. Requested size: 63 hosts
Netmask:   255.255.255.128 = 25 
Network:   192.0.2.0/25         
HostMin:   192.0.2.1            
HostMax:   192.0.2.126          
Broadcast: 192.0.2.127          
Hosts/Net: 126                   Class C

3. Requested size: 30 hosts
Netmask:   255.255.255.224 = 27 
Network:   192.0.2.160/27       
HostMin:   192.0.2.161          
HostMax:   192.0.2.190          
Broadcast: 192.0.2.191          
Hosts/Net: 30                    Class C

Needed size:  192 addresses.
Used network: 192.0.2.0/24
Unused:
192.0.2.192/26

sipcalc

sipcalc is similar to ipcalc. One big difference seems to be the IPv6 support:

$ sipcalc 2001:DB8::/32
-[ipv6 : 2001:DB8::/32] - 0

[IPV6 INFO]
Expanded Address        - 2001:0db8:0000:0000:0000:0000:0000:0000
Compressed address      - 2001:db8::
Subnet prefix (masked)  - 2001:db8:0:0:0:0:0:0/32
Address ID (masked)     - 0:0:0:0:0:0:0:0/32
Prefix address          - ffff:ffff:0:0:0:0:0:0
Prefix length           - 32
Address type            - Aggregatable Global Unicast Addresses
Network range           - 2001:0db8:0000:0000:0000:0000:0000:0000 -
                          2001:0db8:ffff:ffff:ffff:ffff:ffff:ffff

(Thanks to Niall for the pointer to RFC3849. :-)

It can also split up networks into smaller chunks, but only same-size chunks, like e.g. split a /32 IPv6 network into /34 networks:

sipcalc -S34 2001:DB8::/32
-[ipv6 : 2001:DB8::/32] - 0

[Split network]
Network                 - 2001:0db8:0000:0000:0000:0000:0000:0000 -
                          2001:0db8:3fff:ffff:ffff:ffff:ffff:ffff
Network                 - 2001:0db8:4000:0000:0000:0000:0000:0000 -
                          2001:0db8:7fff:ffff:ffff:ffff:ffff:ffff
Network                 - 2001:0db8:8000:0000:0000:0000:0000:0000 -
                          2001:0db8:bfff:ffff:ffff:ffff:ffff:ffff
Network                 - 2001:0db8:c000:0000:0000:0000:0000:0000 -
                          2001:0db8:ffff:ffff:ffff:ffff:ffff:ffff

-

Similar thing with IPv4:

sipcalc -s27 192.0.2.0/24
-[ipv4 : 192.0.2.0/24] - 0

[Split network]
Network                 - 192.0.2.0       - 192.0.2.31
Network                 - 192.0.2.32      - 192.0.2.63
Network                 - 192.0.2.64      - 192.0.2.95
Network                 - 192.0.2.96      - 192.0.2.127
Network                 - 192.0.2.128     - 192.0.2.159
Network                 - 192.0.2.160     - 192.0.2.191
Network                 - 192.0.2.192     - 192.0.2.223
Network                 - 192.0.2.224     - 192.0.2.255

sipcalc also has a “show me all information” mode with the -a option:

$ sipcalc -a 192.168.96.0/21
-[ipv4 : 192.168.96.0/21] - 0

[Classfull]
Host address            - 192.168.96.0
Host address (decimal)  - 3232260096
Host address (hex)      - C0A86000
Network address         - 192.168.96.0
Network class           - C
Network mask            - 255.255.255.0
Network mask (hex)      - FFFFFF00
Broadcast address       - 192.168.96.255

[CIDR]
Host address            - 192.168.96.0
Host address (decimal)  - 3232260096
Host address (hex)      - C0A86000
Network address         - 192.168.96.0
Network mask            - 255.255.248.0
Network mask (bits)     - 21
Network mask (hex)      - FFFFF800
Broadcast address       - 192.168.103.255
Cisco wildcard          - 0.0.7.255
Addresses in network    - 2048
Network range           - 192.168.96.0 - 192.168.103.255
Usable range            - 192.168.96.1 - 192.168.103.254

[Classfull bitmaps]
Network address         - 11000000.10101000.01100000.00000000
Network mask            - 11111111.11111111.11111111.00000000

[CIDR bitmaps]
Host address            - 11000000.10101000.01100000.00000000
Network address         - 11000000.10101000.01100000.00000000
Network mask            - 11111111.11111111.11111000.00000000
Broadcast address       - 11000000.10101000.01100111.11111111
Cisco wildcard          - 00000000.00000000.00000111.11111111
Network range           - 11000000.10101000.01100000.00000000 -
                          11000000.10101000.01100111.11111111
Usable range            - 11000000.10101000.01100000.00000001 -
                          11000000.10101000.01100111.11111110

[Networks]
Network                 - 192.168.96.0    - 192.168.103.255 (current)

Thanks again to Kurt and Niall for their contributions!

Now listening to the schreimaschine and fausttanz submissions for the interactive competition at the Bünzli/DemoDays in Olten (Switzerland)

Tuesday·30·August·2011

Useful but Unknown Unix Tools: watch //at 22:18 //by abe

from the Watch-commands,-not-TV dept.

Yet another useful tool of which at least I heard quite late in my Unix career is “watch”. For a long time I wrote one-liners like this to monitor the output of a command:

while :; do echo -n "`date` "; host bla nameserver; sleep 2; done

But it’s way shorter and less error-prone to use “watch” from Debian’s procps package and just write

watch host bla nameserver

The only relevant difference is that I don’t have some kind of history when the output of the command changed, e.g. to calculate the rate with which a file grows.

You can even track the output of more than one command:

watch 'ps aux | grep resize2fs; df -hl'

Also a nice way to use watch is to run it inside GNU Screen (or tmux or splitvt) and split up the terminal horizontally, i.e. show the output of watch in one window and the process you’re tracking with the commands run by watch in the other window and see both running at the same time.

Update, Sunday, 28th of August 2011, 17:13h

I never found a useful case for watch’s -d option which highlights changes to the previous run (by inverting the changed bytes), but until now three people pointed out the -d option in response to this blog-posting and weasel also had some nice examples, so here are they:

Keep an eye on the current network routes (once per second) of a host and quickly notice when they change:

watch -n1 -d ip r

Watch the current directory for size or time stamp changes of its files:

watch -d ls -l

The option -d only highlights changes from the previous run to the next run. If you want to see all bytes which ever changed since the first run, use --differences=cumulative.

Thanks to Klaus “Mowgli” Ethgen, Ulrich “mru” Dangel, Uli “youam” Martens and Peter “weasel” Palfrader for comments and suggestions.

Useful but Unknown Unix Tools: Kill all processes of a user //at 22:15 //by abe

from the BOFH-slays-users dept.

I already got mails like “What a pity that your nice blog posting series ended”. No, it didn’t end. As announced, I knew that I won’t be able to keep up a daily schedule. It worked as long as I had already written the postings in advanced. But in the end the last postings were already written just in time and then I ran out of leisure and muse for a time. But as I said: It didn’t end, it will be continued. And this is the next such posting.

Oh, and for those who tell me further tools, I should blog about: I appreciate that, especially because that way I also hear about tools I didn’t know about. But why just telling me and not blogging yourself about it? :-) At least those whose blog is part of Planet Debian or Planet Symlink anyway really should do this themselves. I’d really like to see also others writing about cool tools. I neither have a right on the idea nor on the name of this series (call it meme if you want :-), so please go on and publish your favourite tools in a blog posting, too. :-)

And for all those who want to join me and Myon blogging about cool Unix tools, independent if listed on Planet Debian or Planet Symlink, I encourage you to offer a separate feed for this kind of postings and join us on Planet Commandline.

Anyway, here’s the next such posting:

As system administrator you often have the case that you have to kill all processes of one user, e.g. if a daemon didn’t properly shut down itself or amok running leftovers of a GUI session.

Many use pkill -SIGNAL -u user from the procps package or killall -SIGNAL -u user from the psmisc package for it. But that’s a) quite cumbersome to type and b) is there a chance to forget about the -u and then bad things may happen, especially with pkill’s default substring match, so I prefer another tool with a more explicit name:

slay

slay has an easy to remember name (at least for BOFHs ;-) which is even quicker to type (alternating one character with the left and the right hand, at least on US layout keyboards) than “pkill” (all characters to type with the right hand), and has the same easy to remember commandline syntax like kill itself:

slay -SIGNAL user [user …]

But beware, slay is…

… not only for BOFHs, but also from a BOFH

It has a “mean mode” which is activated by default. With mean mode on, it won’t kill the given user but the user who called the program if it is invoked as an ordinary user without root rights. *g*

Interestingly I never ran into this issue despite I use this program often and for many years now.

But some Ubuntu users did, probably because adding a sudo in front of some command is easier to forget than doing an ssh root@localhost or su - beforehand. They even seem to be so desperate about it that they forwarded the issue from Launchpad to the Debian Bug Tracking System. ;-)

But to be honest — even if I was very amused about those bug reports — isn’t this issue “grave”, as it causes very likely (unexpected) data loss?

Now playing: Monzykill dash nine (… and your process is mine ;-)

Saturday·27·August·2011

Useful but Unknown Unix Tools: Calculating with IPs //at 12:22 //by abe

from the juggling-with-netmasks dept.

There are two small CLI tools I need often when I’m handling larger networks or more than a few IP addresses at once:

netmask

netmask is very handy for calculating with netmasks (anyone expected something else? ;-) in all variants:

$ netmask 192.168.96.0/255.255.248.0
    192.168.96.0/21
$ netmask -s 192.168.96.0/21
    192.168.96.0/255.255.248.0  
$ netmask --range 192.168.96.0/21
    192.168.96.0-192.168.103.255  (2048)
$ netmask 192.168.96.0:192.168.103.255
    192.168.96.0/21
$ netmask 192.168.87.0:192.168.110.255
    192.168.87.0/24
    192.168.88.0/21
    192.168.96.0/21
   192.168.104.0/22
   192.168.108.0/23
   192.168.110.0/24
$ netmask --cisco 192.168.96.0/21
    192.168.96.0 0.0.7.255

(The IP ranges in RFC5737 where too small for the examples I had in mind. :-)

There’s though one thing netmask can’t do out of the box and that’s where the second tool comes into play:

prips

When I read the package name prips, I always think of something like “print postscript” or so, but it’s actually an abbreviation for “print IPs”.

And that’s all it does:

$ prips 192.0.2.0/29
192.0.2.0
192.0.2.1
192.0.2.2
192.0.2.3
192.0.2.4
192.0.2.5
192.0.2.6
192.0.2.7
$ prips 198.51.100.1 198.51.100.6
198.51.100.1
198.51.100.2
198.51.100.3
198.51.100.4
198.51.100.5
198.51.100.6
$ prips -i 2 203.0.113.0/28
203.0.113.0
203.0.113.2
203.0.113.4
203.0.113.6
203.0.113.8
203.0.113.10
203.0.113.12
203.0.113.14
$ prips -f hex 192.0.2.8/29
c0000208
c0000209
c000020a
c000020b
c000020c
c000020d
c000020e
c000020f

prips has proven to be very useful in combination with shell loops like these:

$ prips 192.0.2.0/29 | xargs -n 1 host
[…]
$ for ip in `prips 198.51.100.1 198.51.100.6`; do host $ip; done
[…]

And since prips doesn’t support the 192.0.2.0/255.255.255.248 netmask syntax, you can even easily combine those two tools:

$ prips `netmask 192.0.2.0/255.255.255.248`
[…]

(Hah! Now I was able to use RFC5737 IP ranges! ;-)

Monday·08·August·2011

Finding libraries not marked as automatically installed with aptitude //at 17:26 //by abe

from the aptitude-for-the-win-again dept.

This is a direct followup on my blog posting Finding packages for deinstallation on the commandline with aptitude.

In the meantime on more alias for finding obosolete packages made it into my zsh configuration. It’s an alias to find installed libraries, …-data, …-common and other usually only automatically installed packages, which are not marked as being installed automatically nevertheless:

alias aptitude-review-unmarkauto-libraries='aptitude -o "Aptitude::Pkg-Display-Limit=( ^lib !-dev$ !-dbg$ !-utils$ !-tools$ !-bin$ !-doc$ !^libreoffice | -data$ | -common$ | -base$ !^r-base ) !~M"'

And yes, this pattern is slightly larger than those from the previous posting, so here’s the used filter in a little bit more readable way:

(
  ^lib
    !-dev$
    !-dbg$
    !-utils$
    !-tools$
    !-bin$
    !-doc$
    !^libreoffice | 
  -data$ | 
  -common$ | 
  -base$
    !^r-base
)
!~M

It matches all non-automatically installed packages whose name starts with “lib”, but is neither a debug symbols package, a development header package, a documentation package, a package containing supplied commands, nor a libreoffice package.

Additionally it matches all non-automatically installed packages ending in -data, -common, or -base, but excludes r-base packages.

Of course you can then mark any erroneously unmarked library by pressing “M” (Shift-m).

If you press “g” for “Go” afterwards and wonder why nothing to remove shows up, be reminded that the filter limit is active in this view, too. So press “l” for “Limit” and then Ctrl-u to erase the current filter limit of this view and press enter to set the new (now empty) filter, et voilà…

Hope this is of help for some others, too.

Saturday·09·April·2011

Finding packages for deinstallation on the commandline with aptitude //at 20:18 //by abe

from the aptitude-for-the-win dept.

Although I often don’t agree with Erich (especially if GNOME is involved ;-), he recently posted something on Planet Debian which I found very helpful.

I also own a netbook where disk space is sacre. It’s an ASUS EeePC 701 with just 4GB disk space. And it runs Debian Sid, so dependencies change often, leaving packages installed which formerly had hard dependencies on, but are now left with just recommendations pointing to it.

Quite a few times I asked myself if it’s possible to find those packages and if so, how to do it. Well, I don’t have to ask myself that anymore, since Erich recently posted the appropriate filter patterns for my favourite package manager aptitude for this task in his posting “Finding packages for deinstallation”. Thanks, Erich!

Since those filters aren’t very easy to remember, I’d like to extend the usefulness of his posting towards the commandline. I for myself added the following aliases to my shell setup:

alias aptitude-just-recommended='aptitude -o "Aptitude::Pkg-Display-Limit=!?reverse-depends(~i) ~M !?essential"'
alias aptitude-also-via-dependency='aptitude -o "Aptitude::Pkg-Display-Limit=~i !~M ?reverse-depends(~i) !?essential"'

As youam suggested on IRC, I also added the filter !?essential since we won’t touch essential packages when cleaning up the list of installed packages anyway.

Hope this helps further.

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Hackergotchi of Axel Beckert

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Debian GNU/Linux is my favourite Linux distribution, being stable, flexible, consistent and having a great community. Although I'm not the biggest bug report writer, I try to contribute by staffing the Debian booth at events, carrying the necessary hardware there or even organising the whole booth.


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