I have inheritied a script and dont know what this line does :)

This site is best viewed in a modern browser with JavaScript enabled.

I have inheritied a script and dont know what this line does :)

idn

Hi,

I have a perl script which is used to calculate the amount of code churn in perforce (a type of code change contol system);

The system uses the command line to output commands and then grep the results to get the appropiate data.

There is one line however which really confuses me Its this:

$numlines = `p4 print $filename#$revChglistTable{$filename} | wc -l`;
chomp($numlines);

I am not sure what the | wc -1 part and the chomp() does. the

p4 print $filename#$revChglistTable{$filename}

Part is the command output, so you dont really need to worry about that. The question I need answered is:

 wc -1

Is this a perl thing? What does it do? Whenever I run the script I get the following debug message in command prompt:

'wc' is not recognized as an internal or external command,
operable program or batch file.

BTW I am using active perl on windows

Thanks!

NogDog

"wc" is a UNIX/Linux command that gets info on a file (the "-l" says you want a line count), so probably isn't going to work on a Win platform unless you have some sort of UNIX command emulator installed.

NogDog

Here's an alternative way to get the line count:

open(FILE, "< $filename#$revChglistTable{$filename}") or die "can't open $filename: $!";
for ($numlines=0; <FILE>; $numlines++) { }
# you shouldn't need a chomp() in this case

Above derived from http://www.oreilly.com/catalog/cookbook/chapter/ch08.html

idn

Great, thanks alot, Im glad I invetigated it further because it turns out the tool was producing incorrect data because this wasnt working on windows.

Basically, I want to execture the external command:

'p4 print $filename#$revChglistTable{$filename}';

in perl and read back the number of lines it produces. For example if I typed in the command

p4 print //depot/foo#2

the file contents will be output on the command line. I'm not sure how to execture external commands like this in perl, or indeed how to read the contents back into the script (so I can count the number of lines etc)

Thanks!

bluestartech

executing an external command in perl is quite straight forward. say for example you wanted a directory listing (windows or unix):

$directory_listing = dir /home/me;

The backticks indicate that the text be executed as an external command and the output be stored in the variable $directory_listing

Diarmuid Ryan
Web Design Ireland