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Tag Archives: linux

use PAC file for automatic proxy selection

I will explain how to use automatic proxy selection for a local network.

For example let’s say that you have a proxy server but that proxy is not available all time. In this case the you need to find each time if the proxy is alive (available) and if yes to use it. If not then browser will select direct connection.

The easiest way to use it is to create a PAC file and to add it in the Firefox as automatic proxy selection.

Go to Preferences–>Advanced –> Network –>Settings and choose “Automatic proxy configuration URL”

Then type there the path to a local PAC file. Normally there should be a web page address but if the file is locals works also ( no web server needed)

FFsettings

To create the PAC file use any text editor and create a file called “autoproxy.pac” and put this content:

function FindProxyForURL(url, host)
{
return “PROXY 192.168.1.29:3128; DIRECT”;
}

The Proxy in this case is on local network at 192.168.1.29 (Squid Proxy on port 3128) and Firefox try to use it first . In case it is not responding it will use direct connection.

You can set there multiple proxy servers. The order is important.

In the example below you can have two proxies. If the first one (192.168.1.29) is not responding then the second one (192.168.1.42) will be selected, and if the second one also do not respond the direct network connection will be used.

function FindProxyForURL(url, host)
{
return “PROXY 192.168.1.29:3128; PROXY 192.168.1.42:3128; DIRECT”;
}

The name of the PAC file is not important ( “autoproxy.pac” is name used by me), any name will do.

More details regarding the PAC file , examples, more advanced functions can be found here : http://findproxyforurl.com/

 

 

 

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samba server on tinycore linux – howto

Simple setup for samba server on Tinycore linux server. Many tutorials are available on internet but mine is tested and it working as I want.

First install samba package on Tinycore linux.

from “tc” user start tce-ab

Then edit the smb.conf file from /usr/local/etc/samba/smb.conf.
Inside add something like this:

[global]
workgroup = WORKGROUP
netbios name = box
security = user

[atom_1t]
comment = Data
path = /mnt/sda1
read only = no
guest ok = no

Explanations:

security = user
this will create a share that is based on user/password

netbios name = box
this will be the name of your server ( alias to avoid tiping the IP address)

read only = no
to have write access

guest ok = no
no allow of guest users ( no anonymous connections)
Then as root you run this command

 smbpasswd -a <tinycore user>

then type the samba password for that user. You will use this password from the client machine when you will connect to the samba share
then save the samba config files to make the changes persistent after reboot.

add in /opt/.filetool.lst

usr/local/etc/samba/smb.conf            <-- this contain samba setup
usr/local/etc/samba/private/passdb.tdb  <-- this contain your password

then backup with “backup”
and then restart the server

Next go at the client machine and in filemanager type:
smb://box/
and you should get a popup window asking for user and password. Put the user and that password you set on samba.

easy backup system with rsync – like Time Machine

Backup systems are good for recovering in case of accidental  lost data. But a more useful feature is the incremental backup where you have access to various snapshots in time like the Time Machine on Apple is doing. To do this in Linux (or any Unix  or alike ) systems is actually very easy.

For example we make a backup every day ( or every internal you want) . We need that  the amount of data transferred is small and not big. Imagine transferring few TB every day ! in case our important data is changing a little bit then we will backup only the modified parts. For this Rsync is the best tool. Everybody knows that. But there is a problem. How can we keep daily snapshots of the data without filling the disk ? For this we will use softlinks,  hardlinks and Rsync options.

So we have to create a script file like this:

#!/bin/bash
date=`date "+%Y-%m-%dT%H-%M-%S"`
rsync -aP --delete --log-file=/tmp/log_backup.log --exclude=lost+found --link-dest=/mnt/sdb2/Backups/current /mnt/sda1/ /mnt/sdb2/Backups/back-$date
rm -f /mnt/sdb2/Backups/current
ln -s /mnt/sdb2/Backups/back-$date /mnt/sdb2/Backups/current

So here I make first a “date” variable that will be used in the name of the backup folder to easily know when that backup/snapshot was made.

Then use the rsync with some parameters (see man rsync for more details):

-a = archive mode ( to send only changed parts)

-P = to give a progress info – (optional)

–delete = to delete the deleted files from backup in case they are removed from source

–log-file = to save the log into a file (optional)

–exclude = to exclude some folders/files from backup . This are relative to source path !!! do not use absolute path here !

–link-dest = link to the latest backup snapshot

/mnt/sda1 = source path (here I backup a whole drive)

/mnt/sdb2/Backups/back-$date  = destination folder , it will contain all the content from the source.

Then by using rm I remove the old link to the old backup ( the “current” link) and then I replace it with a new soft link to the newly created snapshot.

So now whenever I click on “current” I go in fact to the latest backup .

And because every time I make the backup the date is different the old snapshots will be kept. So for every day I will have a snapshot.

To automate this you have to create a cron job to execute the above script at the convenient time.

Example to run at 4:01AM every day:

1  4 * * * /path/to/script

Please notice that only the first time the full backup will take a long time since it will copy the full data. The second time you will run the script it will transfer only the changed files/bits.

Now on the destination folder you will see a “back-xxx” folder for every time you run the script. You can open/read the files from all this folders as it if they are completely independent files. In fact if you run df and du you will see something interesting.

For example if the backup is 600GB and the script is run every day you will see that the df will show the same 600GB used from disk space. But if you run “du -sh /* ”  you will see that each “back-xxx” folder is 600GB each. This is possible because there are only hardlinks to the same data copied. Do not worry, the disk is not full and you should trust the df results and not the du results.

user@box:/mnt/sdb2/Backups$ du  -sh ./*
623.8G    ./back-2014-02-24T17:47:12
623.8G    ./back-2014-02-24T21-46-41
623.8G    ./back-2014-02-25T17-05-02
623.8G    ./back-2014-02-25T18-45-34
0    ./current
user@box:/mnt/sdb2/Backups$ df /mnt/sdb2
Filesystem                Size      Used Available Use% Mounted on
/dev/sdb2                 2.7T    623.9G      1.9T  24% /mnt/sdb2

So the Time Machine is in fact only 3 lines of code in a script plus a cron job ! Easy and everybody can do it !

Adapt the script to your needs. Run it when you want with cron jobs.

At any point in time you can delete old backups ( for example backups older than few weeks). This can also be made with cron plus some scripts.

Tiny core linux no autologin

on Tiny core Linux distribution the tc user is automatically login at boot time.

If you want this not to happen then you have to change /opt/bootsync.sh file and to add this line :

echo “booting” > /etc/sysconfig/noautologin

and then backup with backup command. Of course all this must be run from root account.

FTP backup with BASH script ( FTP scripting)

FTP protocol is used to transfer data between computers. The user has also a possibility to combine bash scripts with FTP to automate the backups of the files. This concept can be used for example to backup some files from a local machine to a remote server.
The way to do this is by making an executable script that is run from time to time by a cron job task. In this way the backup is made automatically in the background and do not require user intervention. But there is a problem. if you use FTP in command line then you have to type user name and password in clear text. So how to do it ?
The solution I suggest is like in the example below:

First step is to determine if the backup is needed . We check if the file was changed since last backup. For this we use a compare between the size of the file in this moment with the size of the file at the previous backup time. The previous size was saved in a file. To check this we use the “if compare” structure from BASH:

### check if the file was changed, and if YES then make FTP transfer, if not exit
 if [ `cat ~/.size_myfile.txt` -ne `du -s /path/to/file | cut -f1` ] ; then
 echo 'File changed !'
 fi
 ###########################

Then we define some parameters for FTP command. This definition can be made in a different ( hidden) file. For not critical situations ( home users) I recommend keeping the user details in the same file ( in the script) but to remove all the permissions for the other users ( use chmod command ). So the backup script should look like this:

-rwx------ myuser mygroup 32 june 12 14:52 backupFTP.script

Notice that only the “myuser” user has the right to read/write/execute the file

So for FTP command you need:

##############################
 HOST='ftp.myserver.com'
 USER='myusername'
 PASSWD='mypassword'
 FILE='/path/to/filesource filedestination'
ftp -n $HOST <<END_SCRIPT
 quote USER $USER
 quote PASS $PASSWD
 cd /path/to/destination
 put $FILE
 quit
 END_SCRIPT
 #############################

Since the source path and the destination path may be different you can use “cd /path/to/destination” for the file. The copied file can be also renamed as shown above ( see “filedestination“)

Notice that the commands between “END_SCRIPT” tags are executed inside FTP terminal. This are FTP commands and not BASH/Linux commands. You can put here whatever FTP commands you want based on your needs. For a full list of the FTP commands type “help” in the FTP terminal.

The 3rd step is to recalculate and save the new size of the file so that next time when backup script is run the size file is updated. For this we do:

################################
 ## recalculate the new size of the file, for next backup
 du -s /path/to/file | cut -f1 > ~/.size_myfile.txt
 env DISPLAY=:0 notify-send 'FTP backup done !' 'File : /path/to/file'
 ###############################

Optionally you can show a desktop notification that the backup was made. If you do not have a GUI then do not use it.

Next I show the full script in only one file:

#!/bin/bash
 ### check if the file was changed, and if YES then make FTP transfer, if not exit
 if [ `cat ~/.size_myfile.txt` -ne `du -s /path/to/file | cut -f1` ] ; then
#    echo 'File changed !'
 sleep 1
 #
 HOST='ftp.myserver.com'
 USER='myusername'
 PASSWD='mypassword'
 FILE='/path/to/filesource filedestination'
 ftp -n $HOST <<END_SCRIPT
 quote USER $USER
 quote PASS $PASSWD
 cd /path/to/destination
 put $FILE
 quit
 END_SCRIPT
 sleep 1
 ## recalculate the new size of the file, for next backup
 du -s /path/to/file | cut -f1 > ~/.size_myfile.txt
 env DISPLAY=:0 notify-send 'FTP backup done !' 'File : /path/to/file'
fi
 ###############

live USB linux with dd command

I use linux most of the time and from time to time I want to test a new distro. The easy way to try a new distro is to use the USB stick. The CD is outdated and the DVD is expensive.

There are many ways to make a live bootable USB but I want to show the easiest one. All you need is the ISO file and any linux machine. Any Unix OS should be fine but I did not tested.

So no special software is required.

First you have to download the ISO for the distro you want to try. For example Mint, Debian , Ubuntu, etc…etc…

Then open a terminal and use dd command to transfer the ISO image to the USB stick.

For this you need the root privileges. You can become root with su or you can use sudo in front of the command.

So in terminal type (first read this post till end !):

sudo dd if=/path/to/linuxdistro.iso of=/dev/sdb bs=4M ; sync

That’s it ! Now the ISO image is copied on the USB stick and you can boot from it.

Details about the command:

sudo = to get super user privileges, if not then you have to become root first with su command

dd = command to copy to disk

if=/path/file  = select the input file, in this case the ISO file.

of = the destination of the copy

/dev/sdb = your USB device. First check what is the name of your USB stick. You can plug the stick and check it with df command. Do not use any number after sdx since the dd must transfer the ISO file to the disk and not to the partition !

bs=4M = it means to copy up to 4MB at a time – it is optional but it optimize the transfer

sync = optional for the linux OS to flash the buffers

For more info about dd or sync commands please use man from terminal:

man dd

and / or:

man sync

easy way to upgrade Tiny Core Linux 4.x

The Tiny Core Linux is a distro that is very small in size and I personally use it for my home server.

The update/upgrade this distro is actually very easy but the Tiny Core website is chaotic in giving the information. Some pages are outdated ( from 2.x or 3.x versions)

So in my case I had version 4.5.5 and I wanted to upgrade to 4.7.6.

First you have to find what version you have.

Open terminal (any user) and type : version

 

Then the real upgrade begin.

The upgrade is made from 2 steps: first upgrade the TCL (Tiny Core Linux) core and then the extensions ( tcz)

 

So to upgrade the TCL itself you do not need to burn a new CD or use USB sticks , it is enough to download the latest iso file. In my case I downloaded “Core-current.iso” on another linux machine ( client of the TCL server) . Can be made also directly from TCL server but in my case I did not had a software that uncompress ISO files.

Then open the ISO file with a archive manager ( or a similar program that is able to extract files from ISO files). Inside there is a boot folder.

Then copy the content of the unpacked ISO to the TCL disk. In my case I copied from a client machine to the TCL server in a location where I have access to write. In my  TCL server I use  a USB stick as a boot partition “sdc1“. So I saved the files to a sda1 disk.

Now login as  “root” (on TCL server from terminal use “su root“).

Now check what files from the old TCL distro did you changed and which ones are identical with the files from new unpacked ISO file. In my case only /boot/syslinux/syslinux.cfg was customized by me. So I copied all the other files , one by one, and I overwrite the old files from TCL 4.5.5 with the new files (from ISO file).

Then optionally backup the personal settings , if necessary.

Then reboot the system.

After reboot login again as a normal user or as root and check the “version” command to see the new TCL distro version.

 

The second part is to upgrade the TCL extensions.

This can be upgraded independently from TCL core/kernel upgrade described above. Personally I prefer to upgrade them together.

So you have to login as root ( from terminal use “su root“). Then type “tce-update“. Follow the instructions on the screen ( you have to press ENTER ) and at the end reboot again.

 

And this is all you have to do : no CD/USB, only a copy and two reboots. All are done remote.

As an alternative to the ISO unpacking you can use the TCL mirrors that give the upgrade files already unpacked. In my case I was not sure which files I have to copy and I used ISO archive as a reference.

 

 

Add right-click Samba share in Thunar/XFCE file manager

Since I use XFCE4 I was searching a easy way to temporarily share a folder to another PC over the network.

Gnome have a nice and easy way of doing this with a right-click on a selected folder.

But for XFCE there is no such option available. But to fix this you have to create a “custom action”.

Note 1: Samba must be installed for this method to work !

Note 2: I tested this solution on Mint 13/XFCE 64bit. It should work also on Ubuntu 12.04 and higher or similar Linux distros.

Step 1:

In Thunar go to Edit–>Configure custom actions…

xfce_samba2

Then add a new custom action:

xfce_samba4

The command is :

net usershare add %n %f “” Everyone:R guest_ok=y

Notice: copy the above command as it is. The shared folder will have the same icon (not like in Gnome with the special “share” folder icon).

Go on “Appearance conditions” tab and there click only on Directory and remove all the others. The main idea is to see this “share” option only if you selected a folder.

xfce_samba5

Step 2:

Create another custom action for removing the folder from Samba share. The steps are similar but the command is :

net usershare delete %n

xfce_samba8

On the “appearance condition” tab select Directory only.

So at the end you should have two custom actions like in the below example:

xfce_samba10

Step 3: test the new created menu.

Select a folder and right-click and select the share menu you just created. In few seconds you should see that folder on your Samba share. Like this:

xfce_samba7

If you are not sure how to access your Samba shares then you have to type “smb://computername/folder/” like in the above image (in to the address bar). If for some reasons it is not working you can try with the IP address of that PC like : smb://192.168.1.5/

The samba shares can be accessed from any Windows/Linux/Mac computer from any file manager like : Explorer, Dolphin, Nautilus, Thunar, Midnight Commander, total Commander, any web browser…etc

To unshare (not share publicly the folder) you have to make right-click on the same folder but choose the second menu with “unshare”. In few seconds the shared folder will not be publicly available.

Tricks :

  • If you need to write from another computer on to the shared folder then you have to give permision to write (chmod) on that shared folder. You can do this directly inside the custom action command like this :

net usershare add %n %f “” Everyone:F guest_ok=y && chmod 777 %f

It is preferable to use for this a empty folder since it may be dangerous to give 777 permission to everyone.

  • The commands described above can also be run in terminal but you have to replace the %n, %f with the correct values. See above pictures for details.

Screencast with FFMPEG with sound (Ubuntu 12.04 / Mint 13)

This is how to make a high quality screencast with sound from the soundcard.
Great if you want to record for example screencast tutorial or  a webpage that contains sound.
system: Ubuntu 12.04/ Mint 13

  • Record without sound, image size relative to dimensions of your screen (my case is 1600×900):

ffmpeg -f x11grab -s 1600×900 -r 25 -i :0.0 -sameq output.mkv

  • Record with sound, from your microphone:

ffmpeg -f alsa -i pulse -ab 192 -acodec pcm_s16le -f x11grab -s 1600×900 -r 25 -i :0.0 -sameq output.mkv

To record with sound, from your microphone you have to do also the following steps ( only first time):

* Install Pulse Audio Volume Control. (through synaptic package manager)
* Repeat the second command, recording starts.
* Go to Pulse Audio; go to the tab ‘Recording’, it shows ffmpeg recording the sound. Change the pull down menu to Monitor from Built in Analog Stereo.
Now it records the sound stream in stead of your micro. Set your microphone sound level to the desired values.
That is basically it.

After you save the file you will need to cut first few seconds and last few seconds to remove the parts where you start/stop the ffmpeg command.

This can be done with the below command.

Basically in the below example I extract from “output.mkv” the video starting from second 10 . The length of the output file (clip-output-file.mkv) is set to 120seconds.

ffmpeg -ss 10 -t 120 -i output.mkv -acodec copy -vcodec copy clip-output-file.mkv

print some columns from CSV file

If you have a CSV ( comma separated values file) and you need to print only some columns then you can use sed, awk or cut. Today I will show the “cut” command. Do not confuse it with “cat” !!

CUT is quite easy to use and is more simple than AWK or SED. For example if you have a file like this

$ cat datafile.csv

device1 device2 device2a device4b device5a device8 device9

1 56 8 99 5 41 36 8

22 5 99 89 56 56 2

1 0 2 5 9 63 5

As you can see the delimiter is not comma but space. If you want to print only columns 2,3 and 5 then “cut” is the best tool.

$ cut -d” ”  -f2,3,5 datafile.csv

device2 device2a device5a

56 8 5

5 99  56

0 2 9

-d” ” = means to use ” ” (space) as delimiter in the input file

-f2,3,5 = means to print only the fields 2, 3 and 5

So by default the output delimiter is space. If you want a specific delimiter, like tab, you can use this :

$ cut -d” ”  -f2,3,5 –output-delimiter=$’\t’  datafile.csv

device2         device2a        device5a

56                 8                       5

5                   99                     56

0                  2                        9

The syntax $’\t’ is special because cut do not accept TAB as “\t”

For another delimiter you can use the option like : –output-delimiter=”.:.”

$ cut -d” ”  -f2,3,5 –output-delimiter=$’\t’  datafile.csv

device2.:.device2a.:.device5a

56.:.8.:.5

5.:.99.:.56

0.:.2.:.9

Of course for all this there is a AWK or SED command but I think that for simple column selection a CUT command is easier.

More than that. The CUT command give also the possibility to select only some bytes or characters from the file. For example to print only the characters from 2 to 5 you have to use :

$ cut -c2-5 datafile.csv

evic

56

2 5

0

not very useful in my case but nice to have in case the input file format do not have a delimiter.

see more info with “man cut”