Blogging is futile

New web browsers in Wheezy

abe+blog@deuxchevaux.org (Axel Beckert) — Thu, 02 May 2013 16:14:21 +0200

Since there is so much nice new stuff in Debian Wheezy, I have to split up my contributions to Mika’s #newinwheezy game on Planet Debian.

Here’s the next bunch, this time web browsers:

dillo: The FLTK-based lightweight GUI web browser Dillo comes with its own rendering engine (no JavaScript, incomplete CSS support) was already in Debian before, but was removed before the release of Debian Squeeze, because Dillo 2 relied on FLTK 2.x which had an unclear license situation back then and never made it into Debian. In the meanwhile Dillo 3 relies on FLTK 1.3 as FLTK upstream abandoned the 2.0 branch and continued development on the 1.3 branch. So I brought Dillo back into Debian with its 3.0.x release.
netsurf: The RiscOS-originating lightweight GUI web browser Netsurf was already in Debian, too, but didn’t make it into Debian Squeeze as it needed the Lemon parser generator (part of the SQLite source) to build back then and a change in Lemon caused Netsurf to no more build properly in the wrong moment. Netsurf supports CSS 2.1, but has no JavaScript support either. I’d consider its rendering engine more complete than Dillo’s.
surf and xxxterm: Surf and XXXTerm are both simple and minimalistic webkit-based browsers. Surf is easy to embed in other applications and XXXTerm features vi-like keybindings for heavy keyboard users.

To be continued… ;-)

New SSH-related stuff in Wheezy

abe+blog@deuxchevaux.org (Axel Beckert) — Thu, 02 May 2013 15:28:22 +0200

Mika had the nice idea of doing a #newinwheezy game on Planet Debian, so let’s join:

There are (at least) two new SSH related tools new in Debian Wheezy:

mosh: is the “mobile shell”, an UDP based remote shell terminal which works better than SSH in case of lag, packet loss or other forms of bad connection. I wrote about mosh in more detail about a year ago. mosh is also available for Debian Squeeze via squeeze-backports.
sshuttle: is somewhere between port-forwarding and VPN. It allows forward arbitrary TCP connections over an SSH connection without the need to configure individual port forwardings. It does not need root access on the server-side either. I wrote about sshuttle in more detail about a year ago.

To be continued… ;-)

Up to date Aptitude Documentation Online

abe+blog@deuxchevaux.org (Axel Beckert) — Sun, 10 Mar 2013 12:51:26 +0100

Aptitude ships documentation in 7 languages as HTML files. However the latest version available online was 0.4.11.2 from 2008 and hosted on the server by the previous, now unfortunately inactive Aptitude maintainer, and only covered 5 languages.

This lack of up to date online documentation even caused others to put more up to date versions online. Nevertheless they age, too, and the one I’m aware is not up to date for Wheezy.

So the idea was born to keep an up to date version online on Aptitude’s Alioth webspace (which currently redirects to a subdirectory of the previous maintainer’s personal website). But unfortunately we, the current Aptitude Team, are still lacking administrative rights on Aptitude’s Alioth project, which would be necessary to assign new team members who could work on that.

As an intermediate step, there’s now a (currently ;-) up to date Aptitude User’s Manual online in all 7 languages at

http://people.debian.org/~abe/aptitude/

and English at

http://people.debian.org/~abe/aptitude/en/

As this location could also suffer from the same MIA issues as any other “personal” copy, the plan is to move this to somewhere under http://aptitude.alioth.debian.org/ as soon as we have full access to Aptitude’s Alioth project.

Our plans for then are:

Redirects from http://people.debian.org/~abe/aptitude/ to e.g. http://aptitude.alioth.debian.org/doc/, so that all your links to or bookmarks of http://people.debian.org/~abe/aptitude/ are still valid. (This unfortunately won’t work for jump marks to specific sections, just per file, i.e. chapter.)
Set up a cron-job, which keeps the documentation in sync with the version of Aptitude in Unstable (and maybe also with Aptitude in Stable).

P.S.: Anyone interested in doing a German translation of the Aptitude User’s Manual? Sources are in DocBook, i.e. XML, and available via Git.

zutils: zcat and friends on Steroids

abe+blog@deuxchevaux.org (Axel Beckert) — Wed, 21 Nov 2012 01:18:11 +0100

I recently wrote about tools to handle archives conveniently. If you just have to handle compressed text files, there are some widely known shortcut commands to mimic common commands on files compressed with a specific compression format.

	gzip	bzip2	lzma	xz
cat	zcat	bzcat	lzcat	xzcat
cmp	zcmp	bzcmp	lzcmp	xzcmp
diff	zdiff	bzdiff	lzdiff	xzdiff
grep	zgrep	bzgrep	lzgrep	xzgrep
egrep	zegrep	bzegrep	lzegrep	xzegrep
fgrep	zfgrep	bzfgrep	lzfgrep	xzfgrep
more	zmore	bzmore	lzmore	xzmore
less	zless	bzless	lzless	xzless

In Debian and derivatives, those tools are part of the according package for that compression utility, i.e. the zcat command is part of the gzip package and the xzfgrep command is part of the xz-utils package.

But despite this matrix is quite easy to remember, the situation has a few drawbacks:

Those tools can only handle the format they’re written for (which btw. means that all xz-tools can also handle lzma-compressed files as lzma is xz’s predecessor)
zcat and the other cat variants can’t even recognize non-compressed files and throw an error instead of just showing their contents.
I always tend to think that lzcat and friends are for lzip-based compression as xzcat can handle lzma-compressed files anyway.

This is where the zutils project comes in: zutils provides the functionality of most of these utilities, too, but with one big difference: You don’t have to remember, think about or type which compression method has been used for your data, just use zcat, zcmp, zdiff, zgrep, zegrep, or zfgrep and it works — independently of what compression method has been used — if any — or if there are different compression types mixed in the parameters to the same command:

$ zfgrep foobar bla.txt fnord.gz hurz.xz quux.lz bar.lzma

Especially if you use logrotate and let logrotate compress old logs, it’s very comfortable that one command suffices to concatenate all the available logfiles, including the current uncompressed one:

$ zcat /var/log/syslog* | …

Additionally, zutils’ versions of these tools also support lzip-compressed files.

The zutils package is available in Debian starting with Wheezy and in Ubuntu since Oneiric. When being installed, it replaces the original z* utilities from the gzip package by diverting them away.

The only drawback so far is that there neither a zless nor a zmore utility from the zutils project, so zless bla.txt fnord.gz hurz.xz quux.lz bar.lzma will not work as expected even after installing zutils as it is still the one from the gzip package and hence it will show you just the first two files in plain text, but not the remaining ones.

deepgrep: grep nested archives with one command

abe+blog@deuxchevaux.org (Axel Beckert) — Sat, 17 Nov 2012 02:00:12 +0100

Several months ago, I wrote about grep everything and listed grep-like tools which can grep through compressed files or specific data formats. The blog posting sparked several magazine articles and talks by Frank Hofmann and me.

Frank recently noticed that we though missed one more or less mighty tool so far. We missed it, because it’s mostly unknown, undocumented and hidden behind a package name which doesn’t suggest a real recursive “grep everything”:

deepgrep

deepgrep is part of the Debian package strigi-utils, a package which contains utilities related to the KDE desktop search Strigi.

deepgrep especially eases the searching through tar balls, even nested ones, but can also search through zip files and OpenOffice.org/LibreOffice documents (which are actually zip files).

deepgrep seems to support at least the following archive and compression formats:

tar
ar, and hence deb
rpm (but not cpio)
gzip/gz
bzip2/bz2
zip, and hence jar/war and OpenOffice.org/LibreOffice documents
MIME messages (i.e. files attached to e-mails)

A search in an archive which is deeply nested looks like this:

$ deepgrep bar foo.ar
foo.ar/foo.tar/foo.tar.gz/foo.zip/foo.tar.bz2/foo.txt.gz/foo.txt:foobar
foo.ar/foo.tar/foo.tar.gz/foo.zip/foo.tar.bz2/foo.txt.gz/foo.txt:bar

deepgrep though neither seems to support any LZMA based compression (lzma, xz, lzip, 7z), nor does it support lzop, rzip, compress (.Z suffix), cab, cpio, xar, or rar.

Further current drawbacks of deepgrep:

Nearly no commandline options, especially none of the common grep options
No man-page or other documentation
Exit code not related to search results, you have to check the output to see if something has been found

deepfind

If you just need the file names of the files in nested archives, the package also contains the tool deepfind which does nothing else than to list all files and directories in a given set of archives or directories:

$ deepfind foo.ar
foo.ar
foo.ar/foo.tar
foo.ar/foo.tar/foo.tar.gz
foo.ar/foo.tar/foo.tar.gz/foo.zip
foo.ar/foo.tar/foo.tar.gz/foo.zip/foo.tar.bz2
foo.ar/foo.tar/foo.tar.gz/foo.zip/foo.tar.bz2/foo.txt.gz
foo.ar/foo.tar/foo.tar.gz/foo.zip/foo.tar.bz2/foo.txt.gz/foo.txt

As with deepgrep, deepfind does not implement any common options of it’s normal sister tool find.

[The following part has been added on 17-Nov-2012]

As with deepgrep, it also doesn’t seem to support any of the more modern or more exotic compression formats, i.e. it fails on modern debian binary packages which use xz compression on the data part:

deepfind xulrunner-18.0_18.0\~a2+20121109042012-1_amd64.deb
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb/debian-binary
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb/control.tar.gz
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb/control.tar.gz/triggers
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb/control.tar.gz/preinst
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb/control.tar.gz/md5sums
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb/control.tar.gz/postinst
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb/control.tar.gz/control
xulrunner-18.0_18.0~a2+20121109042012-1_amd64.deb/data.tar.xz

[End of part added at 17-Nov-2012]

Dependencies

The package strigi-utils doesn’t pull in the complete Strigi framework (i.e. no daemon), just a few libraries (libstreams, libstreamanalyzer, and libclucene). On Wheezy it also pulls in some audio/video decoding libraries which may make some server administrators less happy.

Conclusion

Both tools are quite limited to some basic use cases, but can be worth a fortune if you have to work with nested archives. Nevertheless the claim in the Debian package description of strigi-utils that they’re “enhanced” versions of their well known counterparts is IMHO disproportionate.

Most of the missing features and documentation can be explained by the primary purpose of these tools: Being backend for desktop searches. I guess, there wasn’t much need for proper commandline usage yet. Until now. ;-)

42.zip

And yes, I was curious enough to let deepfind have a look at 42.zip (the one from SecurityFocus, unzip seems not able to unpack 42.zip from unforgettable.dk due a missing version compatibility) and since it just traverses the archive sequentially, it has no problem with that, needing just about 5 MB of RAM and a lot of time:

[…]
42.zip/lib f.zip/book f.zip/chapter f.zip/doc f.zip/page e.zip
42.zip/lib f.zip/book f.zip/chapter f.zip/doc f.zip/page e.zip/0.dll
42.zip/lib f.zip/book f.zip/chapter f.zip/doc f.zip/page f.zip
42.zip/lib f.zip/book f.zip/chapter f.zip/doc f.zip/page f.zip/0.dll
deepfind 42.zip  11644.12s user 303.89s system 97% cpu 3:24:02.46 total

I though won’t try deepgrep on 42.zip. ;-)

Useful but Unknown Unix Tools: dwdiff better than wdiff + colordiff

abe+blog@deuxchevaux.org (Axel Beckert) — Fri, 16 Nov 2012 01:18:59 +0100

A year ago I wrote in Useful but Unknown Unix Tools: How wdiff and colordiff help to choose the right Swiss Army Knife about using wdiff and colordiff together. Colordiff’ed wdiff output looks like this:

$ wdiff foobar.txt barfoo.txt | colordiff
[-foo-]bar fnord
gnarz hurz quux
bla {+foo+} fasel

But if you have colour, why still having these hard to read wdiff markers still in the text?

There exists a tool named dwdiff which can do word diffs in colour without textual markers and with even less to type (and without being git diff --color-words ;-). Actually it looks like git diff --color-words, just without the git:

$ dwdiff -c foobar.txt barfoo.txt
foo bar fnord
gnarz hurz quux
bla foo fasel

Another cool thing about dwdiff (and its name giving feature) is that you can defined what you consider whitespace, i.e. which character(s) delimit the words. So lets do the example above again, but this time declare that “f” is considered the only whitespace character:

$ dwdiff -W f -c foobar.txt barfoo.txt
foo bar bar fnord
gnarz hurz quux
bla foo fasel

dwdiff can also show line numbers:

$ dwdiff -c -L foobar.txt barfoo.txt
   1:1    foo bar fnord
   2:2    gnarz hurz quux
   3:3    bla foo fasel
$ dwdiff -c -L foobar.txt quux.txt
   1:1    foo bar fnord
   1:2    foobar floedeldoe
   2:3    gnarz hurz quux
   3:4    bla foo fasel

(coloured shell screenshots by aha)

Tools to handle archives conveniently

abe+blog@deuxchevaux.org (Axel Beckert) — Thu, 15 Nov 2012 01:42:33 +0100

TL;DR: There’s a summary at the end of the article.

Today I wanted to see why a dependency in a .deb-package from an external APT repository changed so that it became uninstallable. While dpkg-deb --info foobar.deb easily shows the control information, the changelog is in the filesystem part of the package.

I could extract that one dpkg-deb, too, but I’d have to extract either to some temporary directory or pipe it into tar which then can extract a single file from the archive and sent it to STDOUT:

dpkg-deb --fsys-tarfile foobar.deb | tar xOf - ./usr/share/doc/foobar/changelog.Debian.gz | zless

But that’s tedious to type. The following command is clearly less to type and way easier to remember:

acat foobar.deb ./usr/share/doc/foobar/changelog.Debian.gz | zless

acat stands for “archive cat” is part of the atool suite of commands:

als

lists files in an archive.

$ als foobar.tgz
drwxr-xr-x abe/abe           0 2012-11-15 00:19 foobar/
-rw-r--r-- abe/abe          13 2012-11-15 00:20 foobar/bar
-rw-r--r-- abe/abe          13 2012-11-15 00:20 foobar/foo

acat

extracts files in an archive to standard out.

$ acat foobar.tgz foobar/foo foobar/bar
foobar/bar
bar contents
foobar/foo
foo contents

adiff

generates a diff between two archives using diff(1).

$ als quux.zip
Archive:  quux.zip
  Length      Date    Time    Name
---------  ---------- -----   ----
        0  2012-11-15 00:23   quux/
       16  2012-11-15 00:22   quux/foo
       13  2012-11-15 00:20   quux/bar
---------                     -------
       29                     3 files
$ adiff foobar.tgz quux.zip
diff -ru Unpack-3594/foobar/foo Unpack-7862/quux/foo
--- Unpack-3594/foobar/foo      2012-11-15 00:20:46.000000000 +0100
+++ Unpack-7862/quux/foo        2012-11-15 00:22:56.000000000 +0100
@@ -1 +1 @@
-foo contents
+foobar contents

arepack

repacks archives to a different format. It does this by first extracting all files of the old archive into a temporary directory, then packing all files extracted to that directory to the new archive. Use the --each (-e) option in combination with --format (-F) to repack multiple archives using a single invocation of atool. Note that arepack will not remove the old archive.

$ arepack foobar.tgz foobar.txz
foobar.tgz: extracted to `Unpack-7121/foobar'
foobar.txz: grew 36 bytes

apack

creates archives (or compresses files). If no file arguments are specified, filenames to add are read from standard in.

aunpack

extracts files from an archive. Often one wants to extract all files in an archive to a single subdirectory. However, some archives contain multiple files in their root directories. The aunpack program overcomes this problem by first extracting files to a unique (temporary) directory, and then moving its contents back if possible. This also prevents local files from being overwritten by mistake.

(atool subcommand descriptions from the atool man page which is licensed under GPLv3+. Examples by me.)

I though miss the existence of an agrep subcommand. Guess why?

atool supports a wealth of archive types: tar (gzip-, bzip-, bzip2-, compress-/Z-, lzip-, lzop-, xz-, and 7zip-compressed), zip, jar/war, rar, lha/lzh, 7zip, alzip/alz, ace, ar, arj, arc, rpm, deb, cab, gzip, bzip, bzip2, compress/Z, lzip, lzop, xz, rzip, lrzip and cpio. (Not all subcommands support all archive types.)

Similar Utilities

There are some utilities which cover parts of what atool does, too:

Tools from the mtools package

Yes, they come from the “handle MS-DOS floppy disks tool” package, don’t ask me why. :-)

uz: gunzips and extracts a gzip‘d tar‘d archives; Advantage over aunpack: Less to type. :-); Disadvantage compared to aunpack: Supports only one archive format.
lz: gunzips and shows a listing of a gzip‘d tar‘d archive; Advantage over als: One character less to type. :-); Disadvantage compared to als: Supports only one archive format.

unp

unp extracts one or more files given as arguments on the command line.

$ unp -s
Known archive formats and tools:
7z:           p7zip or p7zip-full
ace:          unace
ar,deb:       binutils
arj:          arj
bz2:          bzip2
cab:          cabextract
chm:          libchm-bin or archmage
cpio,afio:    cpio or afio
dat:          tnef
dms:          xdms
exe:          maybe orange or unzip or unrar or unarj or lha 
gz:           gzip
hqx:          macutils
lha,lzh:      lha
lz:           lzip
lzma:         xz-utils or lzma
lzo:          lzop
lzx:          unlzx
mbox:         formail and mpack
pmd:          ppmd
rar:          rar or unrar or unrar-free
rpm:          rpm2cpio and cpio
sea,sea.bin:  macutils
shar:         sharutils
tar:          tar
tar.bz2,tbz2: tar with bzip2
tar.lzip:     tar with lzip
tar.lzop,tzo: tar with lzop
tar.xz,txz:   tar with xz-utils
tar.z:        tar with compress
tgz,tar.gz:   tar with gzip
uu:           sharutils
xz:           xz-utils
zip,cbz,cbr,jar,war,ear,xpi,adf: unzip
zoo:          zoo

So it’s very similar to aunpack, just a shorter command and it supports some more exotic archive formats which atool doesn’t support.

Also part of the unp package is ucat which does more or less the same as acat, just with unp as backend.

dtrx

From the man page of dtrx:

In addition to providing one command to extract many different archive types, dtrx also aids the user by extracting contents consistently. By default, everything will be written to a dedicated directory that’s named after the archive. dtrx will also change the permissions to ensure that the owner can read and write all those files.
Supported archive formats: tar, zip (including self-extracting .exe files), cpio, rpm, deb, gem, 7z, cab, rar, and InstallShield. It can also decompress files compressed with gzip, bzip2, lzma, or compress.

dtrx -l lists the contents of an archive, i.e. works like als or lz.

dtrx has two features not present in the other tools mentioned so far:

It can extract metadata instead of the normal contents from .deb and .gem files.
It can extract archives recursively, i.e. can extract archives inside of archives.

Unfortunately you can’t mix those two features. But you can use the following tool for that purpose:

deepfind

deepfind is a command from the package strigi-utils and recursively lists files in archives, including archives in archives. I’ve already written a detailed blog-posting about deepfind and its friend deepgrep.

tardiff

tardiff was written to check what changed in source code tarballs from one release to another. By default it just lists the differences in the file lists, not in the files’ contents and hence works different than adiff.

Summary

atool and friends are probably the first choice when it comes to DWIM archive handling, also because they have an easy to remember subcommand scheme.

uz and lz and the shortest way to extract or list the contents of a .tar.gz file. But nothing more. And you have to install mtools even if you don’t have a floppy drive.

unp comes in handy for exotic archive formats atool doesn’t support. And it’s way easier to remember and type than aunpack.

dtrx is neat if you want to extract archives in archives or if you want to extract metadata from some package files with just a few keystrokes.

For listing all files in recursive archives, use deepfind.