Compund command symbols

Sat, 12 Aug 2006 18:51:55 GMT

There are a few cases where I need a batch script to do one thing, and if it fails, do another. There is something that has been around since Windows NT 4.0 to help us create these conditional branches.

The command shell supports running multiple commands on one line. You probably have seen this using the & symbol. The following is a table of compound command sybols and their use:

Symbol                    Use
------------------------------------------------------------------------------------------
Cmd1 & cmd2           Executes command cmd1, then command cmd2.
                             Additional commands can be added using additional ampersand symbols.

Cmd1 && cmd2         Executes command cmd1, then executes command cmd2 only if cmd1 completed successfully.

Cmd1 || cmd2        Executes command cmd1, then executes command cmd2 only if cmd1
                             did not complete successfully.

( )                          Use parentheses to indicate the nesting of complex multi-command sequences.
------------------------------------------------------------------------------------------

In effect, this helps us create an AND and/or an OR conditional branch in our scripts.

Consider the following script where I will use the double ampersand && and the double pipe ||:

I want to create a script that will ping all workstations and give me a file on non-pingable addresses and and a file on pingable addresses…

For /f %a IN (computerlist.txt) Do @(ping -n 1 %a | find /i /c "Request timed out" >NUL && echo %a: No Reply && echo %a >> noreply.txt) || (ping -n 1 %a | find /i /n "Reply from" >NUL && echo %a: Pingable && echo %a >> pingable.txt)

The above script will ping a list of workstations and create two lists, one of computers that did not respond to a ping (noreply.txt) and another that did respond to a ping (pingable.txt) while giving us some output on the screen as well.

To ping a subnet, we can change the For..In..Do loop to process a number set:

For /l %a IN (1,1,255) Do @(ping -n 1 192.168.1.%a | find /i /c "Request timed out" >NUL && echo %a: No Reply && echo %a >> noreply.txt) || (ping -n 1 192.168.1.%a | find /i /n "Reply from" >NUL && echo %a: Pingable && echo %a >> pingable.txt)

The above script would ping 192.168.1.1 through 192.168.1.255 and produce the same output files as above.

The examples above are just to show the possibilities of using compund command symbols and may need to be edited for your specific environment and/or use.

Gill

Gilliath: Scripting - Batch

Compund command symbols