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Sat, Nov 22, 2014 11:46 pm

Appending a date to a filename in batch files

I wanted to append today's date to a file name for a file processed by a batch job on Microsoft Windows systems, specifically a Small Business Server (SBS) 2003 system and Windows 7 and 8 systems. You can obtain the current date using the date /t command (the /t option prevents the command from prompting for a change to the date) or by using echo %date% to display the contents of the date environment variable. However, both of those display the date in the form DDD mm/dd/yyyy, where DDD is the day of the week represented by a 3-character abbrviation, e.g., "Sat", mm is a two-digit representation of the month, e.g., "11" for November, dd is the day and yyyy is the year, on the Windows systems I support.
C:\>date /t
Sat 11/22/2014

C:\>echo %date%
Sat 11/22/2014

You can reformat the representation of the date that is stored in the %date% environment variable, however. I wanted the date in the form yyyymmdd, so that I could stick that at the end of filenames to represent the rotation date for a log file. You can use a command like the one below where a variable, YYYYMMDD is set to hold the reformatted date (the variable name can be anything you like, e.g., mydate, etc., but that name reminds me of the format I'm using for the date.

C:\>set YYYYMMDD=%DATE:~10,4%%DATE:~4,2%%DATE:~7,2%

C:\>echo %YYYYMMDD%

The substring arguments to extract the elements of the date string are in the format %variable:~startposition,numberofchars%, so if the "S" in Saturday in the string "Sat 11/22/2014" is at position 0, the 10th character is the "2" of 2014 and I want 4 characters, i.e., "2014", so %DATE:10,4% will give me those characters. Or you can also think of the first number as the numer of characters to be skipped, i.e., %variable:~num_chars_to_skip,numberofchars%. I can then append %DATE:~4,2% to get "11" for the month followed by %DATE:~7,2% to extract the day, i.e., "22" if the date is November 22, 2014 represented in the %DATE% variable as "Sat 11/22/2014".


  1. How to append a date in batch files
    Posted: May 14, 2009
  2. Extracting a Substring from a String under Microsoft Windows
    MoonPoint Support

[/os/windows/commands] permanent link

Sat, Nov 22, 2014 10:00 pm

Items detected by a ClamWin Scan on 2014-11-22

In continuance of an effort to ensure that all malware has been removed from a Windows 7 Professional system, I scanned the system with ClamWin Free Antivirus today. It identified 12 suspect items, but I'm not sure any of those contributed to excessive memory usage I saw at times on the system yesterday from explorer.exe consuming more than 1/2 the 6 GB of memory on the system for prolonged periods.

[ More Info ]

[/security/malware] permanent link

Sat, Nov 22, 2014 12:25 pm

Determing the location of a Microsoft Windows DNS log file from a command prompt

If you need to determine the location of the log file for a Microsoft Windows server functioning as a DNS server from the command line, you can do so through a reg query command.
C:\>reg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters /v LogFilePath

    LogFilePath    REG_SZ    d:\logs\dns\dns.log

You can reduce the output displayed to just the line containing the log file location by piping the output of the reg query command into the find command.

C:\>reg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters /v LogFilePath | find "LogFilePath"
    LogFilePath    REG_SZ    d:\logs\dns\dns.log

If you wish to see just the log file location and not the other information returned by the reg query command, you can use a FOR /F loop command such as the following:

C:\>for /f "tokens=3" %g in ('reg query "HKLM\SYSTEM\CurrentControlSet\Services\DNS\Parameters" /v LogFilePath ^| find "LogFilePath"') do @echo %g 


The FOR /F loop breaks up a line of output from the command that is being processed into items, called "tokens" that are separated by space on the lines of output from the command. In this case, I'm only interested in the third token on the line of output, which is the location of the DNS log file. The output that is being processed is the result of piping the output of the reg query command into the find command. Since the pipe symbol, i.e., the vertical bar character |, has a special meaning for the Windows operating system, you need to place an "escape character", which for Windows is the caret symbol, ^, immediately before it. You also need to put the at symbol, @, before the echo command to avoid seeing the echo command itself as output.

If you wish to use a batch file to execute the commands to find the log file location, you need to replace the %g with %%g as shown below.

@echo off
FOR /F "tokens=3" %%G IN ('reg query "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters" /v LogFilePath ^| find "LogFilePath"') DO echo %%G

The registry key and the value to be queried can also be placed in environment variables that can be modified, if you wish to query other registry keys, instead of the one for the DNS log file location, so that it is easier to see what needs to be changed for such other queries.

@echo off

REM Name: queryreg.bat
REM Version: 1.0
REM Created: November 22, 2014
REM Last Modified: November 22, 2014
REM Description: Displays just the value of a registry key from a
REM "reg query regkey /v regvalue" command omitting the additional
REM information that is output by the command

set regkey="HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters"
set regvalue="LogFilePath"

FOR /F "tokens=3" %%G IN ('reg query %regkey% /v LogFilePath ^| find %regvalue%') DO echo %%G

Download: queryreg.bat

[/network/dns/windows/logging] permanent link

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