Here is a quick tip on how to make a copy of CD/DVD when the standard CD/DVD burning software is not available. We can use the 'dd' command to copy the CD/DVD as an ISO image file on your harddrive.
dd if=/dev/cdrom of=/tmp/cdimage.iso
1313832+0 records in
1313832+0 records out
672681984 bytes (673 MB) copied, 127.532 s, 5.3 MB/s
bti allows you to send twitter messages right from the command line. It works with both twitter.com and identi.ca. To use this program install the Ubuntu package with the same name (sudo apt-get install bti).
I was able to post a tweet message using bti within few minutes. The configuration is easy and straight forward. Have look at the bti example config file to get started quickly (/usr/share/doc/bti/examples/bti.example). The url shorting feature (with --shrink-urls option) however didn't work as intended though. Anyway its wonderful to be able to tweet from the command line, bti does have some pretty interesting features.
And don't forget to follow my tweets @playingwithsid.
bti provides an easy way to send tweet messages direct from the command line or any script. It reads the message on standard input and uses the account and password settings either from the command line options, or from a config file, to send the message out.
It's primary focus is to allow you to log everything that you type into a bash shell, in a crazy, "this is what I´m doing right now!" type of way, letting the world follow along with you constant moving between directories and refreshing your email queue to see if there´s anything interesting going on.
The devil they say is in details, even the simple Bash path variable can open some security problems on your box. Every Bash documentation out there warns us not leave '.' in the path (it matches current directory). They however don't seems to mention that leaving a dangling ':' (colon) at the beginning or the end of Bash $PATH does create the same security vulnerability.
# Standard Bash $PATH
$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
# Let's get evil, append a colon at the end
$ export PATH="$PATH:"
# Let's check the tainted Bash $PATH
$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:
# Create Trojan application (of sorts)
$ echo "echo foo"> app
$ chmod +x app
# Run the command and Viola!
$ app
foo
Keep things found is not an easy skill to master. The disk drive turns into a deep and dark jungle after the first few weeks on road. Traditional *nix command 'locate' helps us find files quickly by matching against a previously generated database. There are quite a few locate implementations available such as the GNU Findutils, slocate and mlocate, they have quite a few new features and security enhancements.
Unlike its first cousin the 'find' command, locate queries are faster but the exact matches are dependent on the freshness of the database. Also redundancy issue creeps in if you are not watchful. For example, searching with 'locate Simple.pm' gives undesirable results spread across all mounted partitions on this computer.
/mnt/old-drive/usr/share/perl/5.8.4/Filter/Simple.pm # old Linux distro
/usr/share/perl/5.8.8/Filter/Simple.pm # Current OS (Ubuntu/Debian)
/mnt/windows/Perl/lib/Filter/Simple.pm # Windoze XP
Now lets see if we can remedy this by disabling locate indexing of mounted partitions and mounted Windows XP partition as well. Add '/mnt' to the PRUNEPATHS variable and 'vfat' to the PRUNEFS variable to the /etc/updatedb.conf file.
PRUNE_BIND_MOUNTS="yes"
PRUNEPATHS="/tmp /var/spool /mnt "
PRUNEFS="NFS nfs nfs4 afs binfmt_misc proc smbfs autofs iso9660
ncpfs coda devpts ftpfs devfs mfs shfs sysfs cifs lustre_lite
tmpfs usbfs udf rpc_pipefs vfat"
Next time the 'updatedb' command is run to create the locate database it avoids indexing all the directory paths listed under PRUNEPATHS and file systems in PRUNEFS options.
Here is a favorite question often posed to novice sysadmins. Ho, how they would sweat on this one!!. I was pleasantly surprised to see it find its way into Linux Journal's Tech tips. Darn good one Alessandro!.
Less is my default terminal pager program. On GNU Debian Linux pager is just a symbolic link to your less or one of other available pager progams like more , most , lv etc..( run update-alternatives —list pager to find out alternative pager programs available on your computer). Lately some funny characters started showing up in my pager .
$ ls /tmp/Foo/ | pager
ESC[0mESC[0mFooBarESC[0m
ESC[0mMaster-fooESC[0m
ESC[m
Oops, That looks like the ANSI Escape Sequences commonly used for making a shell colourful, but our pager program less seems to have some trouble with it. Let’s try to correct this but using -R option which toggles this behaviour.
$ ls /tmp/Foo/ | pager -R
FooBar
Master-foo
Ok, that seems to fix it. Now let’s set it into our shell environment.You set the same using lesskey also.
LESS=”-R”; export LESS
Please note that using -r option may cause display problems , that’s why I use -R .
Wolfgang Friebel notes in Displaying more with less that ..
Syntax highlighting is only activated if the environment variable LESS is existing and contains the option -R or -r or less is called with one of these options. This guarantees, that instead of literal escape sequences colors are displayed. The detection of the -r/-R presence at runtime is rather dependent on the operating system and may not work in all cases. Putting the option in the LESS environment variable is guaranteed to work.By installing the perl module Proc::ProcessTable the OS dependence can be reduced as well.
Keeping your website updated is tedious job,especially when you have lot of files,which you edit quite often.And having to do the such work over ftp makes it worse.
Now you have a local directory on your computer where you keep all your website files(/home/joe/site_files).Let upload these files to your remote webserver directory using lftp on command line.First lets connect to your hosting service providers webserver with username and password.
$ lftp -u username ftp.hostingcompany.net
Password:
The lftp program will prompt for the password,type your secret password and you will be logged in.
Now issue the ‘lcd’ command to change directory to local directory where your all website files reside.
lftp username@ftp.hostingcompany.net:~> lcd /home/joe/site_files
lcd ok, local cwd=/home/joe/site_files
Now use the lftp mirror built-in’s reverse option (-R) of lftp to
upload all files local files into remote directory on the webserver.
lftp username@ftp.hostingcompany.net:~> mirror -R
Total: 12 directories, 36 files, 0 symlinks
Modified: 13 files, 0 symlinks
You can use “ mirror -R —only-newer “ command if you want only new
files to uploaded.Once the upload is finished lftp will print out a report.Now you can end the connection by typing quit.
lftp username@ftp.hostingcompany.net:~> quit
Now that we have seen lftp in action.Let run all the commands from script instead.Luke Vanderfluit
lftp -u username,password ftp.hostingcompany.net <<EOF
cd / # remote directory on webserver
lcd /home/joe/site_files # local directory on your computer
mirror -R # Upload the files to remote directory
quit 0 # Drop the connection
EOF
Save all the commands in a file ‘upload_mysite’ and make it executable with ‘chmod +x upload_mysite’.Run the script by typing ‘./upload_mysite’ on the command line.As your username and password are stored it file,its a better not let anyone else to view it.Changing file permissions with ‘chmod go-rwx upload_mysite’.
Running lftp from script is not a good idea if you have to maintain multiple sites.Instead you can use lftp’s ‘-f’ option.You can store settings of different websites into separate files.Suppose you have two websites site1 and site2.
The settings of the both the sites are stored in files ‘mysite1.lftp’ and ‘mysite2.lftp.
#####mysite1.lftp#######################
open ftp.myisp.net
user username password
lcd /usr/joe/site1_files
mirror -R
exit
#########################################
#####mysite2.lftp#######################
open ftp.hostingcompany.com
user username password
lcd /usr/local_site_location
mirror -R
exit
#########################################
To update site1, we will run lftp with ‘-f’ option.
$ lftp -f mysite1.lftp
And to update the next website.
$ lftp -f mysite2.lftp
Some other usefull features provided by ‘mirror’ built-in are the —parallel = N where in it will use N simultaneous connections to upload the files,this speeds up the upload considerably.If you want to exclude some files from being uploaded use (- x , – X) . And —delete to remove those files which are not present in local directory.
lftp can also be run as a cron job . Jani Reinikainen
lftp manual page [http://lftp.yar.ru/lftp-man.html ]
lftp FAQ [http://lftp.yar.ru/FAQ ]
lftp Download page [http://lftp.yar.ru/get.html ]
If you have Elinks installed then it already has a bunch of smart URL’s enabled .The table below lists those in Debian’s elinks package configuration file. The Elinks Manual explains how it works and how to build your own.
Here a example, lets search for what acronym “ALSA” means with elinks.
Press g in elinks and type a: ALSA when prompted with Enter URL. The a: is the keyword and ALSA (replaced in place of %s ) is search string, elinks smart rewrite expands it to http://acronymfinder.com/af-query.asp?String=exact&Acronym=ALSA and submits it , You will be directed to the search results at acronymfinder.com.
Tuxmaniac gets his hands dirty with dpatch and documents his experience in a easy to follow tutorial.
One review point that the packager comes across instantly is that “Do not change upstream code”. This is a Golden rule for packagers. Making these changes as patches in debian/ (for debian based distros ofcourse ;-) ) is highly recommended. One such tool for achieving this is DPATCH.
dpatch - just superb! (a short How to)
In October 2005 I contributed to the Guide to Unix/Linux commands wikibook. It is targeted at users who want to learn the shell commands by typing them on a Unix or gnu/Linux console. The wikibook is nowhere near complete but I guess it would be a good start if want to master the shell. For experienced users I request you to spare some time and contribute to this wikibook. If possible please try to adopt this documentation project.
The Guide to Unix/Linux command line is often considered difficult to learn. This book aims to help beginners by introducing various commands in lucid and simple language. Unlike most command references, this book is designed to be a self-study guide.
