Just Host cPanel cleanup script for Greasemonkey
by Mostafa on Oct.23, 2009, under How To ..., Software
I finally decided to get my own domain and signed up with Just Host for the registration and hosting. For now I’m only using it to host this blog that originally started its life on Blogger. The transition was fairly smooth, save for a few minor issues. I’ll talk more about the steps involved a future post (a draft is already in the queue) …
Just Host offers cPanel as a web frontend for managing and running site related tasks. It’s quite a nice tool but there is one big problem. The interface is literally littered with a bunch of annoying ads and affiliate links. Even more annoying is the fact that there doesn’t seem to be any way of permanently moving these offending boxes to the bottom of the screen. This is where Greasemonkey comes in.
Greasemonkey is a nice little extension for Firefox that allows the execution user scripts to change the way a website looks. userscripts.org is a great place for finding scripts that work on major/popular sites on the internet. A search there didn’t turn up anything useful so I decided to write my own. Install Greasemonkey if you don’t have it already and then click on this link to get the script installed. I’ve also put up a copy on userscripts.org.
The script works by setting the ‘display’ style of the offending div boxes to ‘none’. Firebug is another great tool that makes it a breeze to find out the IDs of the divs that need to be blacklisted.
[Update 10-Nov-2009]: Looks like some sneaky new ads injected using Javascript have shown up on the cPanel sidebar. Unlike the old ad boxes however, these lack div IDs. As a result, it is not possible to simply blacklist them. Fortunately, it also means that it is possible to turn the table around by simply blocking the sidebar divs that have a null ID. The script has been updated.
Before:
After:
Status report
by Mostafa on Oct.23, 2009, under Life
Looks like it’s been more than a year since the last time I’ve published something here. I’ve just been really busy, now more than ever. I have been periodically saving some blurbs as drafts but I never quite seem to have the time to polish them into real posts.
I really should be working on my thesis and a number of other papers but it does get a bit tiresome. Whenever that happens, I’ll work a bit on the drafts as a distraction and hopefully manage to push a few of them out over the coming weeks…
Moving from Blogger to WordPress
by Mostafa on Oct.18, 2009, under How To ...
The initial move is easy enough using the Blogger importer plugin of WordPress. Setting up redirects from the old blog to the new one however takes a bit more work. I followed the instructions at:
http://underscorebleach.net/jotsheet/2006/05/move-blogger-to-wordpress
Printing multi-page duplex documents
by Mostafa on Oct.18, 2009, under How To ..., Linux, Software
The psnup tool can be used to place multiple pages on each sheet of a document. E.g., the following command places two pages from the input file into each sheet of the output:
$ psnup -l -2 input.ps output.ps
While psnup is excellent for quick “N-up” conversion jobs, it doesn’t provide much control over the layout. The pstops utility on the other hand allows for fine grained scale, rotation and placement settings for each page that goes into a sheet of the output. The command syntax is a bit more complicated on account of the page specification strings that must now be provided. The following example shows a typical command needed to prepare a document for duplex printing with two pages on each side of a sheet:
$ pstops -pa4 \ '4:0L@0.8(21cm,-1cm)+1L@0.8(21cm,12.55cm),2R@0.8(0,29.85cm)+3R@0.8(0,16.25cm)' \ input.ps output.ps
The command is best understood by referring to the relevant section from the manpage:
Pstops rearranges pages from a PostScript document, creating a new PostScript file. The input PostScript file should follow the Adobe Document Structuring Conventions. Pstops can be used to perform a large number of arbitrary re-arrangements of Documents, including arranging for printing 2-up, 4-up, booklets, reversing, selecting front or back sides of documents, scaling, etc. pagespecs follow the syntax: pagespecs = [modulo:]specs specs = spec[+specs][,specs] spec = [-]pageno[L][R][U][@scale][(xoff,yoff)] modulo is the number of pages in each block. The value of modulo should be greater than 0; the default value is 1. specs are the page specifi- cations for the pages in each block. The value of the pageno in each spec should be between 0 (for the first page in the block) and modulo-1 (for the last page in each block) inclusive. The optional dimensions xoff and yoff shift the page by the specified amount. xoff and yoff are in PostScript’s points, but may be followed by the units cm or in to convert to centimetres or inches, or the flag w or h to specify as a multiple of the width or height. The optional parameters L, R, and U rotate the page left, right, or upside-down. The optional scale param- eter scales the page by the fraction specified. If the optional minus sign is specified, the page is relative to the end of the document, instead of the start. If page specs are separated by + the pages will be merged into one page; if they are separated by they will be on separate pages. If there is only one page specification, with pageno zero, the pageno may be omitted. The shift, rotation, and scaling are performed in that order regardless of which order they appear on the command line.
Restricting access to SFTP / SCP
by Mostafa on Oct.18, 2009, under How To ..., Linux, Software
rssh is a tool that allows SFTP/SCP for file transfers over SSH but denies shell access — useful for preventing users from running commands on the system. More details are available on the tool’s homepage.
I first came across it on this page.
Realtime collaborative text editing
by Mostafa on Nov.21, 2008, under Linux, Software
A while ago, I came across Etherpad. It a web based platform that allows multiple users to simultaneously edit a single text file. Since it doesn’t seem to support any kind of mark-up at the moment, it would seem that it’s not terribly useful for word processing tasks. Perhaps it’s good for real-time collaborative coding and the creation of agenda type lists …
The software equivalent of Etherpad is Gobby. It’s a multi-platform tool that claims to run on Microsoft Windows, Mac OS X, Linux and other Unix-like platforms — making it almost as flexible as a web-based service. There are a number of other advantages:
- Flexibility and security that comes from having absolute control over the sessions.
- Syntax highlighting!
Bash process substitution
by Mostafa on Oct.03, 2008, under Linux, Software
From the Advanced Bash-Scripting Guide:
“Piping the stdout of a command into the stdin of another is a powerful technique. But, what if you need to pipe the stdout of multiple commands? This is where process substitution comes in.
Process substitution feeds the output of a process (or processes) into the stdin of another process.”
The syntax is:
>(cmd_list) <(cmd_list)
Example: comparing the head of two files using diff
$ diff -u <(head -n3 /var/log/dmesg) <(head -n3 /tmp/dmesg) --- /proc/self/fd/63 2009-05-26 19:52:45.144544140 +0100 +++ /proc/self/fd/62 2009-05-26 19:52:45.149544007 +0100 @@ -1,3 +1,3 @@ -Initializing cgroup subsys cpuset -Initializing cgroup subsys cpu -Linux version 2.6.27.21-170.2.56.fc10.i686 (mockbuild@xenbuilder2.fedora.redhat.com) (gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC) ) #1 SMP Mon Mar 23 23:37:54 EDT 2009 +Linux version 2.6.22.9-61.fc6 (brewbuilder@hs20-bc2-4.build.redhat.com) (gcc version 4.1.2 20070626 (Red Hat 4.1.2-13)) #1 SMP Thu Sep 27 18:48:03 EDT 2007 +BIOS-provided physical RAM map: + BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
The diff header clearly shows that file descriptors are used as the underlying mechanism.
Re-encoding MP3 files using LAME
by Mostafa on Jun.06, 2008, under How To ..., Linux, Software
I have some MP3 files encoded at a constant bitrate of 320kbps that my phone seems to have trouble playing smoothly. So, I looked into LAME.
The files I had were named using the following scheme:
01 - Title of track 01.mp3 02 - Title of track 02.mp3 ...
I used the BASH for-loop construct to process the files:
$ for A in *.mp3;\ # Process one mp3 at a time do B=${A%.mp3};\ # Extract track number and title C=${B#?? -};\ # Extract the title D=${B%% - *};\ # Extract the track number lame --vbr-new -V0 -q0\ # Variable-bitrate, high-quality --mp3input\ # Inputs are MP3 files --tt "$C"\ # ID3v2 tags: title --ta 'Artist Name'\ # ID3v2 tags: artist --tl 'Album Title'\ # ID3v2 tags: album --ty 2007\ # ID3v2 tags: year --tn "$D"\ # ID3v2 tags: track no. --tg 'GENRE'\ # ID3v2 tags: genre "$A" processed/"$A";\ # Keep filename and save in ./processed/ done
Since no bit-rate bounds are explicitly provided, the re-encoded files can contain anything between 32kbps and 320kbps. The LAME man-page provides an extensive list of options and their meanings.
Processing files using ‘find’
by Mostafa on Mar.26, 2008, under How To ..., Linux, Software
In its most basic form, find is often used to locate files that are subsequently piped through a complex set of commands for processing. However, this particular method is easily broken by files that contain spaces in their names.
This is where the ‘exec’ option provided by find comes in handy. From the man-page:
-exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of ‘;’ is encountered. The string ‘{}’ is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a ‘\’) or quoted to protect them from expansion by the shell. See the EXAMPLES sec- tion for examples of the use of the ‘-exec’ option. The speci- fied command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec option; you should use the -execdir option instead.
An example that recursively touches all *.log files from the current directory would be:
$ find . -name \*.log -exec touch {} \;