Special or Difficult Characters

Hopefully "ScriptingTipsAndTricks" helps you with your batch file or vbscript scripting :-)

Introduction

Special or Difficult Characters

Special or Difficult Characters

The following characters have special meaning and may need careful handling in your batch files:

Character Details

| A single vertical bar character (above "\" on keyboard) is used to indicate piping of one programs output into another.

< and > These two characters indicate redirection. ">>" means append to the file you are directing to.

& A single ampersand character is used to separate multiple commands on a single line.
This also allows it to be used as follows:
set EndsWithFiveSpaces=Something &rem The 5 spaces before the ampersand are significant

It is also used in redirection, for example "2>&1" means send stderr output to the same place that stdout is going to.

^ The "hat" character is used to escape the "|", "<", ">" and "&" characters if required (it can also be used to escape itself).
This will only be required if they are not within double quotes:
ECHO This ^& that ECHO "This & that" ECHO "This & that" ^& This Again

If you use a hat when its not required it will be kept so you need to be careful.

* The asterisk character can be used in the "SET" command but it has special meaning there and so is the only difficult character for that particular command :-)
The "ReplaceAsterisks() example shows how you can replace this character if required.

% (percent)
and
! (exclamation mark) These characters are used to perform parameter and environment variable expansion (retrieval).
The ! character only has special meaning when "delayed expansion (ENABLEDELAYEDEXPANSION)" is on. This can be very handy if you are passed the name of a variable and you wish to obrain its contents.
To escape "%" use two ("%%) and for "!" use "^!" when within double quotes otherwise "^^!" :-)
@echo off setlocal ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION set Something=This is the value set VarName=Something echo %VarName% = !%VarName%! echo I want to display this: "%%" and this: '%%' echo I want to display this: "^!" and this: '^^!'

Character	Details
\|	A single vertical bar character (above "\" on keyboard) is used to indicate piping of one programs output into another.
< and >	These two characters indicate redirection. ">>" means append to the file you are directing to.
&	A single ampersand character is used to separate multiple commands on a single line. This also allows it to be used as follows: set EndsWithFiveSpaces=Something &rem The 5 spaces before the ampersand are significant It is also used in redirection, for example "2>&1" means send stderr output to the same place that stdout is going to.
^	The "hat" character is used to escape the "\|", "<", ">" and "&" characters if required (it can also be used to escape itself). This will only be required if they are not within double quotes: ECHO This ^& that ECHO "This & that" ECHO "This & that" ^& This Again If you use a hat when its not required it will be kept so you need to be careful.
*	The asterisk character can be used in the "SET" command but it has special meaning there and so is the only difficult character for that particular command :-) The "ReplaceAsterisks() example shows how you can replace this character if required.
% (percent) and ! (exclamation mark)	These characters are used to perform parameter and environment variable expansion (retrieval). The ! character only has special meaning when "delayed expansion (ENABLEDELAYEDEXPANSION)" is on. This can be very handy if you are passed the name of a variable and you wish to obrain its contents. To escape "%" use two ("%%) and for "!" use "^!" when within double quotes otherwise "^^!" :-) @echo off setlocal ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION set Something=This is the value set VarName=Something echo %VarName% = !%VarName%! echo I want to display this: "%%" and this: '%%' echo I want to display this: "^!" and this: '^^!'

Microsoft awarded me an MVP (Most Valuable Professional award) in 2004, 2005, 2006, 2007, 2008 & 2009 for the Windows SDK (Windows Installer) area.

Please email me any feedback, additional information or corrections.
See this page online (look for updates)