The Windows NT command language supports Conditional Processing Symbols, Filters, and Redirection. These can be used in batch processing as well as at a command prompt.
Symbols:
The ampersand (&) separates multiple commands on one command line.
The parentheses groups multiple commands.
The semicolon or comma or equal sign (; , =) separate command parameters.
The caret (^) allows you to use a command symbol as text, ignoring the symbols meaning.
The double ampersand (&&) causes the command following this symbol to run if the command preceding the symbol is successful.
The double pipe (||) causes the command following this symbol to run if the command preceding the symbol fails.
Examples:
Dir <drive:>\Directory1&Dir <drive:>\Directory2 - executes both Dir commands
Dir <drive:>\Directory1=<drive:>\Directory2 - executes the Dir command on both directories
net use <drive:> \\Server\Share&&echo OK - displays ok the first time but not subsequently as the <drive:> is already used
Redirection characters change where a command gets information from or sends information to:
The greater-than sign (>) sends the output of a command to a file or a device, such as a printer. If the file exists, it is 1st deleted.
The double greater-than sign (>>) sends the output of a command to a file. If the file exists, it is extended, if it doesn't exist, it is created.
The less-than sign (<) takes the input for a command from a file.
Examples:
Dir <drive:>\Directory1 > <drive:>\Directory2\dirlist.txt - creates a new dirlist.txt file with the output of the dir command.
Dir <drive:>\Directory3 >> <drive:>\Directory2\dirlist.txt - adds the output of this dir command to the file created above.
Filters divide, order, or extract portions of the information that pass through them:
The find command searches files for the string you specify.
The sort command orders files.
Examples:
sort < list.txt > sort.txt - orders the lines of list.txt as sort.txt.
find ".EXE" < Dirlist.txt > EXE.txt - finds upper case .EXE extensions and creates the lines that contain them in EXE.txt
Here is a batch file I call 1Meg.bat which I use to find all files over 1 megabyte in the target directories:
Usage: 1meg <drive:>\Directory1,<drive:>\Directory2,...<drive:>\Directoryn
output: 1meg_YourUserId.log in the current directory
1meg.bat:
@echo off
dir /o-s /c /n %* > %TMP%\%USERNAME%tmp.log
find "replace this string with 14 spaces" %TMP%\%USERNAME%tmp.log /V > %TMP%\%USERNAME%tmp1.log
find "<DIR>" %TMP%\%USERNAME%tmp1.log /V > %TMP%\%USERNAME%tmp.log
find "Volume " %TMP%\%USERNAME%tmp.log /V > %TMP%\%USERNAME%tmp1.log
find " File(s)" %TMP%\%USERNAME%tmp1.log /V > %TMP%\%USERNAME%tmp.log
find "%TMP%\%USERNAME%TMP" %TMP%\%USERNAME%tmp.log /V /I > %0\...\1meg_%USERNAME%.log
del %TMP%\%USERNAME%tmp*.log
exit
NOTE: See tip 5921 » How do I tee console messages (stdout and/or stderr)?
