How to choose the right WiFi channel

If you setup your wireless access point, you may want to configure it in such a way minimizing interference in your neighborhood. I found this interesting post with some tips:

• There must be a spacing of at least 5 channels (or more) between each WiFi network in order to avoid interferences. Two WiFi networks operating on the same channel are forced to share bandwidth, as they can't "talk" simultaneously, which halves each network's bandwidth. In order to evade this effect, you need to change your access point's channel, but taking the adjacent one won't do it, as WiFi channels are arranged in an overlapping pattern, as you can see in the scheme below. The default channel of most wifi devices is channel 6, so in many cases channel 11 or higher are a good choice. Using NetStumbler one can very easily see which channels is used for each access point.
  
  
  
  
  
  
  
  


• If all your WiFi-devices support 802.11g (the 54 MBit/s WiFi-variant), you should set your router to 802.11g-only mode, as the 802.11b-compatibility impacts on bandwidth and range even among 802.11g-devices.


• Another possible cause of low performance may be proprietary WiFi acceleration modes like "SuperG", "MAXg", "125 High Speed Mode" or "SpeedBooster", if not all devices in your network support the very same mode, why you should disable those.


• Also note that a lot of cordless phones in NZ operate at the 2.4 GHz band like Wifi and so most of them cause interferences WiFi, that can't be avoided by a channel change, since those phones use a very broad spectrum or perform permanent frequency hopping.
  
  
  If you own a 2.4 GHz phone, try switching it off and removing the power supply of it's base station. In case your wireless signal improves, replace your cordless phone with a new one operating at 1.8 GHz or 5.8 GHz.


• A cheap and easy solution to extend the coverage of your WiFi environment is to place a repeater at the correct location. It will repeat the wireless signal and extend the coverage (no cables needed), without creating a new network. Many very cheap (+-10euro) wifi access points (for example my DLink DWL-G700AP) can be configured to work as a repeater instead of the default access point functionality.


• Transmit power: In most cases, the transmit power should be set to the highest value. This maximizes range, which reduces the number of access points and cost of the system. If you're trying to increase the capacity of the network by placing access points closer together, set the power to a lower value to decease overlap and potential interference. Lower power settings also limit the wireless signals from propagating outside the physically controlled area of the facility, which improves security.


• Service Set IDentifier (SSID): The SSID defines the name of a WLAN that users associate with. By default, the SSID is set to a common value, such as tsunami for Cisco products. In order to improve security, you should change the SSID to a non-default value to minimize unauthorized users from associating with the access point. For even better security, some access points let you disable SSID broadcasting. This keeps most client device operating systems (e.g., Windows XP) from sniffing the SSID from access point beacons and automatically associating with the access point. Someone could, however, obtain the SSID using other sniffing tools that obtain the SSID from 802.11 frames when users first associate with the access point.


• Data rate: Most access points allow you to identify acceptable data rates. By default, 802.11b access points operate at 1, 2, 5.5, and 11Mbps data rates, depending on the quality of the link between the client device and the access point. As the link quality deteriorates, the access point will automatically throttle down to lower data rates in an attempt to maintain a connection. You can, however, exclude specific data rates. For example, you may want communications only at 11Mbps or not at all. This could be necessary to support higher bandwidth applications.


• Beacon interval: The beacon interval is the amount of time between access point beacon transmissions. The default value for this interval is generally 10ms, that is 10 beacons sent every second. This is sufficient to support the mobility speed of users within an office environment. You can increase the beacon interval and have lower overhead on the network, but then roaming will likely suffer. It's best to leave this setting alone.


• Request-to-send / clear-to-send (RTS / CTS): The RTS / CTS function alleviates collisions due to hidden nodes, which is when multiple stations are within range of a common access point but out of range of each other. In most cases, it's best to disable RTS / CTS, but refer to a previous tutorial for cases where RTS / CTS may be beneficial and what threshold values to use.


• Fragmentation: Fragmentation can help reduce the amount of data needing retransmission when collisions or radio frequency (RF) interference occurs. As with RTS/ CTS, refer to a previous tutorial for cases where fragmentation may be beneficial and applicable threshold values.

Wifi security

• The impact on the performance by using WEP or WPA really depends on the router. Underpowered old routers don't like the encryption overhead and will slow down somewhat. It is expected to be about 10-15% for either WEP or WPA on older units. In many cases, it's also affected by the speed of the client computer, especially if the WPA encryption is done in driver. Fortunately, this hasn't been the case for many years. These days, there's hardly any slowdown of using WEP or WPA on the performance. However, there's a huge difference in security between WEP and WPA.


• A nice overview on the weakest to the strongest wireless security capacity is:


• 
  

  
  

  
  
  • Considered as not safe:
  
  
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    • No Security
    
    
    • Switching Off SSID: same has No Security. SSID can be easily sniffed even if it is Off
    
    
    • MAC Filtering: only to be used if nothing else is available, MAC number can be easily Spoofed
    
    
    • WEP64: Easy to "Break" by knowledgeable people
    
    
    • WEP128: A little Harder, but still easy to "Break" by knowledgeable people
    
    

    
    

    
    
  
  
  • Considered as safe:
  
  
  • 
    

    
    

    
    
    • WPA-PSK: Very Hard to Break
    
    
    • WPA-AES: Not functionally Breakable
    
    
    • WPA2: Not functionally Breakable
    
    

    
    

    
    
  
  

  
  

  
  


• If you use Windows XP bellow SP3 and did not updated it, you would have to download the WPA2 patch from Microsoft.


• The documentation of your Wireless devices (Wireless Router, and Wireless Computer's Card) should state the type of security that is available with your Wireless hardware.


• All devices MUST be set to the same security level using the same pass phrase. Therefore the security must be set according whatever is the best possible of one of the Wireless devices. I.e. even if most of your system might be capable to be configured to the max. with WPA2, but one device is only capable to be configured to max . of WEP, to whole system must be configured to WEP.


• Even when using WPA2, one still has to be careful and never use the default WEP or WPA password and default SSID. Different applications exist to recover the default WEP/WPA password based on the SSID. For Alcatel / Thomson SpeedTouch router this online generator can be very easy to recover the default password based on the SSID.

Find-Replace text in files from command line

In Linux one can easily find and replace some text in files by using the sed application. In Windows, I couldn’t find a decent build in equivalent. I ended by using the ported version of sed for Windows. I works quite well using the same syntax and doesn’t require to be installed. Just make sure sed.exe, libiconv2.dll and libintl3.dll are existing in the same folder or on the classpath.

One should know any file altered by sed for Windows will result in this file being also converted from Windows line ending (using 2 characters: Carriage Return + Line Feed) to Linux line endings (only 1 character: Line Feed). This can sometime give some strange results. To overcome this, one should make sure the last replacement in the file is set to replace the Line Feeds back to Carriage Return + Line Feed:

sed -i "s/$/\r/" "%DIR%\file.txt"

Some other useful sed commands are available from sed sourcefourge:

FILE SPACING:
 # double space a file
 sed G
 # double space a file which already has blank lines in it. Output file
 # should contain no more than one blank line between lines of text.
 sed '/^$/d;G'
 # triple space a file
 sed 'G;G'
 # undo double-spacing (assumes even-numbered lines are always blank)
 sed 'n;d'
 # insert a blank line above every line which matches "regex"
 sed '/regex/{x;p;x;}'
 # insert a blank line below every line which matches "regex"
 sed '/regex/G'
 # insert a blank line above and below every line which matches "regex"
 sed '/regex/{x;p;x;G;}'
NUMBERING:
 # number each line of a file (simple left alignment). Using a tab (see
 # note on '\t' at end of file) instead of space will preserve margins.
 sed = filename | sed 'N;s/\n/\t/'
 # number each line of a file (number on left, right-aligned)
 sed = filename | sed 'N; s/^/     /; s/ *\(.\{6,\}\)\n/\1  /'
 # number each line of file, but only print numbers if line is not blank
 sed '/./=' filename | sed '/./N; s/\n/ /'
 # count lines (emulates "wc -l")
 sed -n '$='
TEXT CONVERSION AND SUBSTITUTION:
 # IN UNIX ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format.
 sed 's/.$//'               # assumes that all lines end with CR/LF
 sed 's/^M$//'              # in bash/tcsh, press Ctrl-V then Ctrl-M
 sed 's/\x0D$//'            # works on ssed, gsed 3.02.80 or higher
 # IN UNIX ENVIRONMENT: convert Unix newlines (LF) to DOS format.
 sed "s/$/`echo -e \\\r`/"            # command line under ksh
 sed 's/$'"/`echo \\\r`/"             # command line under bash
 sed "s/$/`echo \\\r`/"               # command line under zsh
 sed 's/$/\r/'                        # gsed 3.02.80 or higher
 # IN DOS ENVIRONMENT: convert Unix newlines (LF) to DOS format.
 sed "s/$//"                          # method 1
 sed -n p                             # method 2
 # IN DOS ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format.
 # Can only be done with UnxUtils sed, version 4.0.7 or higher. The
 # UnxUtils version can be identified by the custom "--text" switch
 # which appears when you use the "--help" switch. Otherwise, changing
 # DOS newlines to Unix newlines cannot be done with sed in a DOS
 # environment. Use "tr" instead.
 sed "s/\r//" infile >outfile         # UnxUtils sed v4.0.7 or higher
 tr -d \r <infile >outfile            # GNU tr version 1.22 or higher
 # delete leading whitespace (spaces, tabs) from front of each line
 # aligns all text flush left
 sed 's/^[ \t]*//'                    # see note on '\t' at end of file
 # delete trailing whitespace (spaces, tabs) from end of each line
 sed 's/[ \t]*$//'                    # see note on '\t' at end of file
 # delete BOTH leading and trailing whitespace from each line
 sed 's/^[ \t]*//;s/[ \t]*$//'
 # insert 5 blank spaces at beginning of each line (make page offset)
 sed 's/^/     /'
 # align all text flush right on a 79-column width
 sed -e :a -e 's/^.\{1,78\}$/ &/;ta'  # set at 78 plus 1 space
 # center all text in the middle of 79-column width. In method 1,
 # spaces at the beginning of the line are significant, and trailing
 # spaces are appended at the end of the line. In method 2, spaces at
 # the beginning of the line are discarded in centering the line, and
 # no trailing spaces appear at the end of lines.
 sed  -e :a -e 's/^.\{1,77\}$/ & /;ta'                     # method 1
 sed  -e :a -e 's/^.\{1,77\}$/ &/;ta' -e 's/\( *\)\1/\1/'  # method 2
 # substitute (find and replace) "foo" with "bar" on each line
 sed 's/foo/bar/'             # replaces only 1st instance in a line
 sed 's/foo/bar/4'            # replaces only 4th instance in a line
 sed 's/foo/bar/g'            # replaces ALL instances in a line
 sed 's/\(.*\)foo\(.*foo\)/\1bar\2/' # replace the next-to-last case
 sed 's/\(.*\)foo/\1bar/'            # replace only the last case
 # substitute "foo" with "bar" ONLY for lines which contain "baz"
 sed '/baz/s/foo/bar/g'
 # substitute "foo" with "bar" EXCEPT for lines which contain "baz"
 sed '/baz/!s/foo/bar/g'
 # change "scarlet" or "ruby" or "puce" to "red"
 sed 's/scarlet/red/g;s/ruby/red/g;s/puce/red/g'   # most seds
 gsed 's/scarlet\|ruby\|puce/red/g'                # GNU sed only
 # reverse order of lines (emulates "tac")
 # bug/feature in HHsed v1.5 causes blank lines to be deleted
 sed '1!G;h;$!d'               # method 1
 sed -n '1!G;h;$p'             # method 2
 # reverse each character on the line (emulates "rev")
 sed '/\n/!G;s/\(.\)\(.*\n\)/&\2\1/;//D;s/.//'
 # join pairs of lines side-by-side (like "paste")
 sed '$!N;s/\n/ /'
 # if a line ends with a backslash, append the next line to it
 sed -e :a -e '/\\$/N; s/\\\n//; ta'
 # if a line begins with an equal sign, append it to the previous line
 # and replace the "=" with a single space
 sed -e :a -e '$!N;s/\n=/ /;ta' -e 'P;D'
 # add commas to numeric strings, changing "1234567" to "1,234,567"
 gsed ':a;s/\B[0-9]\{3\}\>/,&/;ta'                     # GNU sed
 sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta'  # other seds
 # add commas to numbers with decimal points and minus signs (GNU sed)
 gsed -r ':a;s/(^|[^0-9.])([0-9]+)([0-9]{3})/\1\2,\3/g;ta'
 # add a blank line every 5 lines (after lines 5, 10, 15, 20, etc.)
 gsed '0~5G'                  # GNU sed only
 sed 'n;n;n;n;G;'             # other seds
SELECTIVE PRINTING OF CERTAIN LINES:
 # print first 10 lines of file (emulates behavior of "head")
 sed 10q
 # print first line of file (emulates "head -1")
 sed q
 # print the last 10 lines of a file (emulates "tail")
 sed -e :a -e '$q;N;11,$D;ba'
 # print the last 2 lines of a file (emulates "tail -2")
 sed '$!N;$!D'
 # print the last line of a file (emulates "tail -1")
 sed '$!d'                    # method 1
 sed -n '$p'                  # method 2
 # print the next-to-the-last line of a file
 sed -e '$!{h;d;}' -e x              # for 1-line files, print blank line
 sed -e '1{$q;}' -e '$!{h;d;}' -e x  # for 1-line files, print the line
 sed -e '1{$d;}' -e '$!{h;d;}' -e x  # for 1-line files, print nothing
 # print only lines which match regular expression (emulates "grep")
 sed -n '/regexp/p'           # method 1
 sed '/regexp/!d'             # method 2
 # print only lines which do NOT match regexp (emulates "grep -v")
 sed -n '/regexp/!p'          # method 1, corresponds to above
 sed '/regexp/d'              # method 2, simpler syntax
 # print the line immediately before a regexp, but not the line
 # containing the regexp
 sed -n '/regexp/{g;1!p;};h'
 # print the line immediately after a regexp, but not the line
 # containing the regexp
 sed -n '/regexp/{n;p;}'
 # print 1 line of context before and after regexp, with line number
 # indicating where the regexp occurred (similar to "grep -A1 -B1")
 sed -n -e '/regexp/{=;x;1!p;g;$!N;p;D;}' -e h
 # grep for AAA and BBB and CCC (in any order)
 sed '/AAA/!d; /BBB/!d; /CCC/!d'
 # grep for AAA and BBB and CCC (in that order)
 sed '/AAA.*BBB.*CCC/!d'
 # grep for AAA or BBB or CCC (emulates "egrep")
 sed -e '/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d    # most seds
 gsed '/AAA\|BBB\|CCC/!d'                        # GNU sed only
 # print paragraph if it contains AAA (blank lines separate paragraphs)
 # HHsed v1.5 must insert a 'G;' after 'x;' in the next 3 scripts below
 sed -e '/./{H;$!d;}' -e 'x;/AAA/!d;'
 # print paragraph if it contains AAA and BBB and CCC (in any order)
 sed -e '/./{H;$!d;}' -e 'x;/AAA/!d;/BBB/!d;/CCC/!d'
 # print paragraph if it contains AAA or BBB or CCC
 sed -e '/./{H;$!d;}' -e 'x;/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d
 gsed '/./{H;$!d;};x;/AAA\|BBB\|CCC/b;d'         # GNU sed only
 # print only lines of 65 characters or longer
 sed -n '/^.\{65\}/p'
 # print only lines of less than 65 characters
 sed -n '/^.\{65\}/!p'        # method 1, corresponds to above
 sed '/^.\{65\}/d'            # method 2, simpler syntax
 # print section of file from regular expression to end of file
 sed -n '/regexp/,$p'
 # print section of file based on line numbers (lines 8-12, inclusive)
 sed -n '8,12p'               # method 1
 sed '8,12!d'                 # method 2
 # print line number 52
 sed -n '52p'                 # method 1
 sed '52!d'                   # method 2
 sed '52q;d'                  # method 3, efficient on large files
 # beginning at line 3, print every 7th line
 gsed -n '3~7p'               # GNU sed only
 sed -n '3,${p;n;n;n;n;n;n;}' # other seds
 # print section of file between two regular expressions (inclusive)
 sed -n '/Iowa/,/Montana/p'             # case sensitive
SELECTIVE DELETION OF CERTAIN LINES:
 # print all of file EXCEPT section between 2 regular expressions
 sed '/Iowa/,/Montana/d'
 # delete duplicate, consecutive lines from a file (emulates "uniq").
 # First line in a set of duplicate lines is kept, rest are deleted.
 sed '$!N; /^\(.*\)\n\1$/!P; D'
 # delete duplicate, nonconsecutive lines from a file. Beware not to
 # overflow the buffer size of the hold space, or else use GNU sed.
 sed -n 'G; s/\n/&&/; /^\([ -~]*\n\).*\n\1/d; s/\n//; h; P'
 # delete all lines except duplicate lines (emulates "uniq -d").
 sed '$!N; s/^\(.*\)\n\1$/\1/; t; D'
 # delete the first 10 lines of a file
 sed '1,10d'
 # delete the last line of a file
 sed '$d'
 # delete the last 2 lines of a file
 sed 'N;$!P;$!D;$d'
 # delete the last 10 lines of a file
 sed -e :a -e '$d;N;2,10ba' -e 'P;D'   # method 1
 sed -n -e :a -e '1,10!{P;N;D;};N;ba'  # method 2
 # delete every 8th line
 gsed '0~8d'                           # GNU sed only
 sed 'n;n;n;n;n;n;n;d;'                # other seds
 # delete lines matching pattern
 sed '/pattern/d'
 # delete ALL blank lines from a file (same as "grep '.' ")
 sed '/^$/d'                           # method 1
 sed '/./!d'                           # method 2
 # delete all CONSECUTIVE blank lines from file except the first; also
 # deletes all blank lines from top and end of file (emulates "cat -s")
 sed '/./,/^$/!d'          # method 1, allows 0 blanks at top, 1 at EOF
 sed '/^$/N;/\n$/D'        # method 2, allows 1 blank at top, 0 at EOF
 # delete all CONSECUTIVE blank lines from file except the first 2:
 sed '/^$/N;/\n$/N;//D'
 # delete all leading blank lines at top of file
 sed '/./,$!d'
 # delete all trailing blank lines at end of file
 sed -e :a -e '/^\n*$/{$d;N;ba' -e '}'  # works on all seds
 sed -e :a -e '/^\n*$/N;/\n$/ba'        # ditto, except for gsed 3.02.*
 # delete the last line of each paragraph
 sed -n '/^$/{p;h;};/./{x;/./p;}'
SPECIAL APPLICATIONS:
 # remove nroff overstrikes (char, backspace) from man pages. The 'echo'
 # command may need an -e switch if you use Unix System V or bash shell.
 sed "s/.`echo \\\b`//g"    # double quotes required for Unix environment
 sed 's/.^H//g'             # in bash/tcsh, press Ctrl-V and then Ctrl-H
 sed 's/.\x08//g'           # hex expression for sed 1.5, GNU sed, ssed
 # get Usenet/e-mail message header
 sed '/^$/q'                # deletes everything after first blank line
 # get Usenet/e-mail message body
 sed '1,/^$/d'              # deletes everything up to first blank line
 # get Subject header, but remove initial "Subject: " portion
 sed '/^Subject: */!d; s///;q'
 # get return address header
 sed '/^Reply-To:/q; /^From:/h; /./d;g;q'
 # parse out the address proper. Pulls out the e-mail address by itself
 # from the 1-line return address header (see preceding script)
 sed 's/ *(.*)//; s/>.*//; s/.*[:<] *//'
 # add a leading angle bracket and space to each line (quote a message)
 sed 's/^/> /'
 # delete leading angle bracket & space from each line (unquote a message)
 sed 's/^> //'
 # remove most HTML tags (accommodates multiple-line tags)
 sed -e :a -e 's/<[^>]*>//g;/</N;//ba'
 # extract multi-part uuencoded binaries, removing extraneous header
 # info, so that only the uuencoded portion remains. Files passed to
 # sed must be passed in the proper order. Version 1 can be entered
 # from the command line; version 2 can be made into an executable
 # Unix shell script. (Modified from a script by Rahul Dhesi.)
 sed '/^end/,/^begin/d' file1 file2 ... fileX | uudecode   # vers. 1
 sed '/^end/,/^begin/d' "$@" | uudecode                    # vers. 2
 # sort paragraphs of file alphabetically. Paragraphs are separated by blank
 # lines. GNU sed uses \v for vertical tab, or any unique char will do.
 sed '/./{H;d;};x;s/\n/={NL}=/g' file | sort | sed '1s/={NL}=//;s/={NL}=/\n/g'
 gsed '/./{H;d};x;y/\n/\v/' file | sort | sed '1s/\v//;y/\v/\n/'
 # zip up each .TXT file individually, deleting the source file and
 # setting the name of each .ZIP file to the basename of the .TXT file
 # (under DOS: the "dir /b" switch returns bare filenames in all caps).
 echo @echo off >zipup.bat
 dir /b *.txt | sed "s/^\(.*\)\.TXT/pkzip -mo \1 \1.TXT/" >>zipup.bat

End (kill) some application from command line

Different methods exist in Windows to end or kill some application from command line.

The normal way to do this is by using the TASKKILL command, for example to end FireFox one can use:

TASKKILL /F /IM “firefox.exe”

When you need to stop some command window it can be dangerous to just kill any cmd.exe, so one could use the window title to kill a specific batch window, for example to kill any batch window with name starting with “SIM-” I used:

TASKKILL /FI "WINDOWTITLE eq SIM-*"

But sometimes you’ll need to be more specific, I wanted an automated way to kill some Java application but only when it was started with some specific parameter. The only way I found to do so on Windows was by using the WMIC commands. This example show how I killed our Java monitor application which started as follows:

java -Dapp.prop.file.monitor="monitor_system.properties" -classpath SOME_JARS Monitor

Kill this specific Java instance:

wmic process where "name like '%%java.exe%%' AND commandline like '%%monitor%%'" DELETE

Before killing your application, you want to make sure your query will result in the correct process, one can easily check the query by executing the similar wmic command without yet killing the process:

wmic process where "name like '%%java.exe%%' AND commandline like '%%monitor%%'" get processid, name, commandline /VALUE

More examples and combinations that can be used with wmic are available on this page.

The Linux equivalent we used was pkill, for example to kill our simulators we used:

pkill -f "simulator.jar"

SVN Automated repeated backup / dump – Windows / Linux

Every project using SVN should have an automated backup system in place for their SVN repository. We decided we wanted a weekly incremental backup. But we also wanted to easily create a new initial backup. I scripted it on Windows and Linux with the Shell/Batch scripts shown below.

For both scripts, the same methods is used: we keep track of the last backed up revision in a file called svn_backup_delta.txt. Every time the script is started, an incremental dump is exported and archived, starting from the last dumped revision till the latest available revision. If the latest revision is the same as the last dumped revision, nothing will happen.

If the svn_backup_delta.txt doesn’t exist or the revision could not be read correctly, a complete initial dump from revision 0 till the latest revision will be exported and archived. The scripts are called daily or weekly with a standard OS scheduler. When we want to have a new initial complete dump, we simply remove the svn_backup_delta.txt file.

The scripts can be a good starting point to create your own automated SVN dumping mechanism.

Windows backup_svn.bat Batch script. This script now expects the svn.exe and svnrdump.exe to be in the same folder as the script. It also requires a repos.txt and backup.properties files in the same folder. The output of the script will be stored in the same folder within the file backup_svn.log.

@echo off 
  TITLE %~n0 - see log %~n0.log 
  echo All details will be logged into %~n0.log 
  CALL :STARTBATCH >> %~dp0%~n0.log 2>&1 
  GOTO :EOF

:STARTBATCH     REM All properties are set in backup.properties     REM Variables that change in a for loop, should be marked with !VARIABLE! instead of %VARIABLE%     REM Necessary to use this, otherwise SET !VARIABLE! in for loop fails     setlocal enabledelayedexpansion     ::CONFIGURATION     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% CHECKING FOR CHANGES AT %DATE%: %TIME%     REM Get properties from backup.properties and set as variables     FOR /F "tokens=1,2 delims==" %%A IN (%~dp0backup.properties) DO (     echo %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% %%A: %%B     set %%A=%%B     ) 
  :END_CONFIGURATION

REM Loop through all repos 
  for /f "delims=," %%r in (%~dp0repos.txt) DO ( 
  echo. 
  ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Starting SVN backup 
  ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Using following configuration: 
  SET REPO_URL=%REPO_BASE%/%%r 
  ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% -Repository URL: "%REPO_BASE%/%%r" 
  SET LAST_DELTA_FILE=%DUMP_BASE%\%%r\svn_backup_delta_%%r.txt 
  ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% -File to keep track of last revision backed up: !LAST_DELTA_FILE! 
  SET DUMP_FILE=%DUMP_BASE%\%%r 
  SET Today=%Date: =0% 
  SET Today=!Today:~-4!%Date:~-7,2%%Date:~-10,2% 
  SET Now=%Time: =0% 
  FOR /F "tokens=1,2 delims=:.," %%A IN ("!Now!") DO SET Now=%%A%%B

IF NOT EXIST "!DUMP_FILE!" mkdir "!DUMP_FILE!" 
  %~dp0svn --username %SVN_USERNAME% --password %SVN_PASS% --non-interactive --trust-server-cert --no-auth-cache info !REPO_URL! > %TEMP%\repoinfo.tmp

SET LAST_REV= 
  for /f "usebackq tokens=1,2 delims=: " %%i in (`find "Revision: " "%TEMP%\repoinfo.tmp"`) do (     SET LAST_REV=%%j     )     REM Check if !LAST_REV! retrieved of SVN is a number. If not, exit script.     echo !LAST_REV!| findstr /r "^[0-9]*$">nul || ( ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% ERROR: Last revision number is !LAST_REV! of %%r doesn't seem to be valid, aborting.     GOTO :END )     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Last revision: !LAST_REV!     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Last delta file: !LAST_DELTA_FILE!     REM Check if full backup exists, if true, do an incremental backup     IF NOT EXIST !LAST_DELTA_FILE! (         ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Not delta file found, processing full export         call :FULL     ) ELSE (         ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Delta found, processing delta         call :DELTA     ) 
  ) 
  ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% All repo's done, backup finalized 
  GOTO :END

REM Do an incremental backup 
  :DELTA     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% DELTA     SET LAST_DELTA=     for /f "usebackq tokens=1,2 delims=: " %%i in (`find "Revision: " "!LAST_DELTA_FILE!"`) do (         SET LAST_DELTA=%%j     )     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Last delta:!LAST_DELTA!     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Last revision:!LAST_REV!     IF "!LAST_DELTA!"=="" GOTO FULL     IF "!LAST_REV!"=="" GOTO :END     IF "!LAST_DELTA!"=="!LAST_REV!" GOTO :END     REM Check if !LAST_DELTA! is a number. If not, exit script.         echo !LAST_DELTA!| findstr /r "^[1-9][0-9]*$">nul || ( ECHO ERROR: DELTA REVISION NUMBER IN !LAST_DELTA_FILE! OF %REPO_URL% DOESN'T SEEM TO BE A NUMBER... ABORTING BACKUP...     GOTO :END )     SET /A INCRE_LAST_DELTA=LAST_DELTA+1     SET DUMP_FILE_NAME=!Today!-!Now!-INCREMENTAL-R!INCRE_LAST_DELTA!-TO-R!LAST_REV!.dump     SET DUMP_FILE=!DUMP_FILE!\!DUMP_FILE_NAME!     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Creating dump file name: !DUMP_FILE_NAME!, !DUMP_FILE!     %~dp0svnrdump --username %SVN_USERNAME% --password %SVN_PASS% --non-interactive --trust-server-cert --no-auth-cache dump !REPO_URL! -r !INCRE_LAST_DELTA!:!LAST_REV! --incremental > !DUMP_FILE!     echo %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% %~dp0%ZIP% a -tzip  !DUMP_FILE!.zip !DUMP_FILE! -v%MAX_SIZE%     call %~dp0%ZIP% a -tzip  !DUMP_FILE!.zip !DUMP_FILE! -v%MAX_SIZE%     IF EXIST !DUMP_FILE!.zip DEL /F !DUMP_FILE!     IF EXIST !DUMP_FILE!.zip.* DEL /F !DUMP_FILE!     ECHO Revision: !LAST_REV! > !LAST_DELTA_FILE!     IF EXIST "!LAST_DELTA_FILE!" GOTO DELTA     GOTO :END

REM Do a full backup 
  :FULL     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% FULL     ECHO FULL > !LAST_DELTA_FILE!     SET DUMP_FILE_NAME=!Today!-!Now!-INITIAL-R!LAST_REV!.dump     SET DUMP_FILE=!DUMP_FILE!\!DUMP_FILE_NAME!     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Dump file name: !DUMP_FILE_NAME!     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% Dump file: !DUMP_FILE!     %~dp0svnrdump --username %SVN_USERNAME% --password %SVN_PASS% --non-interactive --trust-server-cert --no-auth-cache dump !REPO_URL! -r 0:!LAST_REV! > !DUMP_FILE!     echo %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% %~dp0%ZIP% a -tzip !DUMP_FILE!.zip !DUMP_FILE! -v%MAX_SIZE%     call %~dp0%ZIP% a -tzip !DUMP_FILE!.zip !DUMP_FILE! -v%MAX_SIZE%     IF EXIST !DUMP_FILE!.zip DEL /F !DUMP_FILE!     IF EXIST !DUMP_FILE!.zip.* DEL /F !DUMP_FILE!     ECHO Revision: !LAST_REV! > !LAST_DELTA_FILE!     IF EXIST "!LAST_DELTA_FILE!" GOTO DELTA     GOTO :END

:END     ECHO %Date:~-4%%Date:~-7,2%%Date:~-10,2%-%Time% END     GOTO :EOF

Linux svnbackup.sh Shell script:

#!/bin/sh
#SETUP
REPO_URL=https://url:8443/base/project
REPO_PATH=c:/repository/project
DUMP_DIR=/home/user/dumps
LAST_DELTA_FILE=svn_backup_delta.txt
#BEGINING OF THE SCRIPT ITSELF
date=$(date +%Y%m%d)
LOG=dump-$date.log
LAST_REV=$(svn info $REPO_URL |grep Revision |gawk ' { print $2}')
#Both files MUST exist, otherwise, wer'e going to init new "delting"
if [ -e $LAST_DELTA_FILE ] ; then
LAST_DELTA=$(cat $LAST_DELTA_FILE)
if [ $LAST_DELTA -ne $LAST_REV ] ; then
DUMP_FILE_NAME=$date-INCREMENTAL-R$((LAST_DELTA+1))-TO-R$LAST_REV.dump.gz
DUMP_FILE=$DUMP_DIR/$DUMP_FILE_NAME
svnadmin dump $REPO_PATH -r $((LAST_DELTA +1)):$LAST_REV --incremental --deltas 2>>$LOG |gzip -c > $DUMP_FILE
else
echo nothing to do : last revision number is same as last delta number, run it again later !
exit 0
fi
else
DUMP_FILE_NAME=$date-INITIAL-R$LAST_REV.dump.gz
DUMP_FILE=$DUMP_DIR/$DUMP_FILE_NAME
svnadmin dump $REPO_PATH 2>>$LOG | gzip -c > $DUMP_FILE
fi
#Is all ok ?
if [ $? -eq 0 ] ; then
echo -n $LAST_REV > $LAST_DELTA_FILE
else
echo "ERROR :" $date "Problem occured while saving dump" >>$LOG
fi

Update 02/07/2010: Script tested and working in Windows 7 (in combination with Visual SVN server). Make sure to add the bin folder of Visual SVN server to your 'path' system variable to make the 'svn' command available system wide. Run the script with right-click 'Run as administrator'.

 

Update 27/06/2016 on Windows script to use a backup_properties.txt, repo.txt files and validate the retrieved revision and delta numbers before executing the windows backup