QR Codes:

A QR code (abbreviated from Quick Response code) is a type of matrix barcode (or two-dimensional code) first designed for the automotive industry. More recently, the system has become popular outside of the industry due to its fast readability and large storage capacity compared to traditional UPC barcodes. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be made up of four standardized kinds (“modes”) of data (numeric, alphanumeric, byte/binary, Kanji), or by supported extensions virtually any kind of data. (source: wikipedia [code for mobile QR code image scanners to the right])

QR codes generators:

URL:

Google Charts: http://chart.apis.google.com/chart?cht=qr&chs=200×200&chld=l&chl=http%3A%2F%2Fen.qrwp.org%2FQr_code

SPARQCode:

Phone Numbers:

Usability settings:

• move window-bar action buttons from left (Ubuntu 10.10/Mac) to right:

  gconftool-2 – type string – set /apps/metacity/general/button_layout "menu:minimize,maximize,close"

• remove confirmation for logout: System Settings -> Advanced -> Session Manager -> Confirm Logout
• remove screen-lock after screensaver: Control Center -> Screensaver -> Lock screen when screensaver is active (uncheck)

Processes management:

• move a process to background (suspend):

  CTRL-z

• list background/suspended processes:

  jobs (returns a list of ids of the stopped processes and their description: [1]+  Stopped  mc)

• bring process to foreground:

  fg 1 (where 1 is the id of the desired process to resurrect from the above list)

Computer info:

Inventory:

• # lists your hardware

  $ sudo lshw

• # lists all hard disk

  $ sudo lshw -C disk

• # xports an html page with hardware details

  $ sudo lshw -html > your-file-name.html

Sensors monitoring:

• sudo apt-get install lm-sensors sensors-applet  #(ksensors for Kubuntu)

• sudo sensors-detect

To see if your running kernel is 32-bit or 64-bit, just issue the following command:

• $ uname -m
  x86_64 indicates a running 64-bit kernel. If you use see i386, i486, i586 or i686, you're running a 32-bit kernel. Note: x86_64 is synonymous with amd64.

How to find out the Ubuntu / Kubuntu version:

• Debian:

   cat /etc/debian_version

• Ubuntu / Kubuntu:

  • cat /etc/issue

  • lsb-release -a (sau  cat /etc/lsb-release)

Change default browser:

•  update-alternatives – config x-www-browser or  update-alternatives – config www-browser 

Display (only) symbolic links with details

•  sudo find / -type l -print | xargs ls -lh

Display files/folder space usage

•  GUI: 
• FileLight, Disk Space Analyzer or gdmap  (Gnome) 
•  KDiskFree or KDirStat (KDE)

•   CLI:

• ncdu – interactive tool
• df -h
• du -bsh {FOLDER_NAME}
• du –max-depth=1 * | sort -n
• Find the top 10 biggest files: find . -type f -print0 | xargs -0 du -s | sort -n | tail -10 | cut -f2 | xargs -I{} du -sh {} 

Manage iso images and CD/DVD’s:

Create ISO imags from CD/DVD:


$ dd if=/dev/dvd of=dvd.iso # for dvd
$ dd if=/dev/cdrom of=cd.iso # for cdrom
$ dd if=/dev/scd0 of=cd.iso # if cdrom is scsi

These commands are useful for data CD/DVD images. For Audio CD’s there’s another (longer) story. (A simpler way would be to use specialized apps like: K3b, Acetoneiso, Brasero)

Create ISO image from folders:

$ mkisofs -v -o /tmp/user-folder.iso -R /home/user/user-folder

Write ISO images to CD/DVD:

• Find out your CDR/W SCSI address/device name:
  $ cdrecord -scanbus
• Write ISO image:
  $ cdrecord -v -dao dev=1,0,0 speed=8 file.iso
  (Where, -speed=XX : Specify writing speed, -v : Verbose output, -dev : The virtual SCSI ID of the writing device [discovered with the earlier command])

Mount / Umount / Format

•  sudo mount /dev/sdb1 /media/USB -t vfat  (sau ntfs / ext2/3/4) - montare partitie

•  sudo umount /dev/sdb1  - demontare partitie

•  sudo mkfs -t vfat /dev/sdb1  - formatare partitie

•  sudo eject /dev/sdb1 

Install software packages:

Subiectul este destul de bine detaliat aici. Pe scurt:

• .tar.gz / .tar.bz2:
  • extract sources:

    •  tar xzvf tarballname.tar.gz 

    •  tar xjvf tarballname.tar.bz2 

  • configure:

    •  cd tarballname 

    •  ./configure 

  • compile sources:

    •  make  [all]

    •  sudo checkinstall  [care inlocuieste:  sudo make install ]

• .deb:
  • graphic mode: double-click the file
  • console:

     sudo dpkg -i file.deb 

• .rpm:
  • conversion in .deb:

     sudo alien -k file.rpm  (after  sudo apt-get install alien , if not already installed)

  • install:

     sudo dpkg -i file.deb 

Calculate md5 checksums:

• for a string:

    echo -n "aaaaaa" | md5sum 

• for a file:

    md5sum file 

For Loop in Bash:

• The simple bash loop to do something with all files in the directory is:

   for f in * ; do echo $f ; done

  which just displays all files in this case.

  This is easy, what I usually need and often forget how to do it is to execute some action exact number of times. Something like simple for loop in C or Java. And there is an exact match for such loop in Bash too:

   for (( i=1 ; i

  I found another similar solution on the Internet today at spiralbound.net:

   for i in $(seq 1 100); do echo $i ; done

Renamefiles:

• UPPERCASE → lowercase

    rename ‘y/A-Z/a-z/’ * 

Empty existing files / Create new (temporary) files:

•  echo "" > file 

•  cp /dev/null file 

•  dd if=/dev/zero of=output.file bs=1 count=1 

•  cat /dev/null > your_file 

•  >filename

•  touch /tmp/newfilename

• command: mktemp which outputs something like: /tmp/tmp.yTfJX35144 script example:

    #!/bin/bash OUT=$(mktemp /tmp/output.XXXXXXXXXX) || { echo "Failed to create temp file"; exit 1; }  echo "Today is $(date)" >> $OUT 

Source: here and here.

Switch from openjdk to sunjdk

• Enable the Canonical Partner Software through the following steps:

  Go to Ubuntu Software Center.
  Click Edit.
  Click Software Sources.
  Switch to the Other Software tab and check Canonical Partners. This may take some time.

• In the Commandprompt, type the following sequence of commands:

  sudo apt-get update
  sudo apt-get install sun-java6-jre sun-java6-plugin
  sudo update-alternatives – config java

Postari relationate:

• Comenzi utile
• The 5-Minute Essential Shell Tutorial – @linuxmint
• Erori Ubuntu / Kubuntu si rezolvarile lor

Aplicatii utile:

consola: konsole (pt KDE–Kubuntu) sau terminal (pt Gnome-Ubuntu) sudo apt-get install terminator (o consola ‘evoluata’ – [l]userii stiu de ce!)

vim (text editor), wicd (network manager – interactiv install), mc (file manager [text-mode]) or krusader sau gnome-commander (file-managers [graphic mode]), sun-java6-jre sun-java6-plugin sun-java6-fonts sun-java6-jdk (java – for netbeans++ – interactiv install), sshfs (mounts ssh locations as folders), cvs, hg (version control system), htop (process viewer), ailurus (ubuntu apps tweaker), synaptic (apps manager – graphical interface)

• sudo apt-get install vim mc terminator sshfs htop ailurus hg rar unrar arj p7xip-full xarchiver pidgin thunderbird tomboy xvnc4viewer wine filezilla ffmpeg mencoder alien
• sudo apt-get install wicd sun-java6-jre sun-java6-plugin sun-java6-fonts sun-java6-jdk

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