copy cd cd .. cd / – Change dir – change to parent dir
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u: – change partition
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help – list commands
Windows shell scripting
The shell reads, “parses” and executes the line
I write a batch file and run it
The shell displays the line it reads from the batch file executes command and displays result
ANNOYING ANNOYING The Theshell shelldisplays displaysall all the thecommands commandsits its about aboutto toexecute execute
@Echo off at the start of your script stops + The @ stops Echo Off being displayed + Echo off stops + the shell displaying REM statements + the shell displaying the commands its about to execute
nice
Scripts obtain information from four basic sources: • Information you write, or hard-code, into the script • Echo Windows is in the C:\winnt directory.
• Information from environment variables • Echo Windows is in the %SYSTEMROOT% directory.
• Information from arguments • c:\mybatch.bat arg1 arg2 • You sent arg1 and arg2 into the program
• Information from executed commands (i.e., command output)
Your own Environment Variables • Use the set command to assign (string) values to variables • Use /a switch to assign result of math operation to variable • Extract value from variable using %var_name%
Using command line arguments • %1 is first arg • %2 is the second arg • notice you only use one % in this case
Limiting scope of variable • use Setlocal and EndLocal
Program Control • Normally, all commands in the batch file will be executed in the order in which they appear in the file. – This is called a sequence.
• Sometimes, there are circumstances in which you would like to carry out commands in a different order or carry out a single command repeatedly. • echo off REM print Paul all over the screen label :start echo Paul goto start REM end of program
Command Redirection •
If you run the command • Echo Fred was here
– the screen displays the text Fred was here.
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Redirect a command's output to a file with redirection symbols. –
> (overwrite) and >> (append) Echo Fred was here > C:\fredreport.txt
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Creates (or overwrites) fredreport.txt with Fred was here Echo Barney was here >> C:\fredreport.txt
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Creates (or appends) fredreport.txt with Barney was here
EQU (equal to) NEQ (not equal to) LSS (less than) LEQ (less than or equal to) GTR (greater than) GEQ (greater than or equal to)
IF Examples IF EXIST C:\install.log (echo complete) ELSE (echo failed) IF DEFINED _department ECHO Got the department variable IF DEFINED _commission SET /A _salary=%_salary% + %_commission% IF CMDEXTVERSION 1 GOTO start_process IF ERRORLEVEL EQU 2 goto sub_problem2
Does the batch file have an argument? (i.e. Does %1 exist?) REF: Question 2 exercises To test for the existence of a command line paramater - use empty brackets like this IF [%1]==[ ] ECHO Value Missing or IF [%1] EQU [ ] ECHO Value Missing
http://www.ss64.com/nt/index.html
Execute code if a condition doesn’t exist
Readability • You can improve the readability of a batch script by writing a complex IF...ELSE command over several lines using brackets e.g. IF EXIST filename (del filename) ELSE (echo The file was not found.)
Simple looping
Combining commands • Dir /ad C:\ | Find /i "winnt" – lists directories (only) and send results to Find which will perform a case insensitive search for the string “winnt” in the file – The | is a pipe and it sends output from first command to second
