what does this mean in shell programming? thanks

topheraholic · 12-19-2008, 08:47 PM

stringZ=abcABC123ABCabc
echo `expr match "$stringZ" '$.[b-c]*[A-Z]..[0-9]$'` # abcABC1

you can see there is a "." and "*",what do they mean? why there is a . and * ?
thanks!

Simon Bridge · 12-19-2008, 09:00 PM

Homework?
You need to review your course notes about how regular expressions work.

topheraholic · 12-19-2008, 09:26 PM

Quote:

Originally Posted by Simon Bridge

Homework?
You need to review your course notes about how regular expressions work.

no,it is not homework, i am new to shell, this is just the thing i do not understand.
thanks

topheraholic · 12-19-2008, 09:55 PM

[QUOTE=Simon Bridge;3381762]Homework?
You need to review your course notes about how regular expressions work.[/QUOTE

i have seen this, but i still donot get it!

why there is two "."~

could you tell me more? thanks.

Simon Bridge · 12-19-2008, 10:49 PM

Not homework eh? It's a standard exercize in string manipulation.
See:
http://tldp.org/LDP/abs/html/string-manipulation.html

play with the expression - what happens if you change the stringZ? What happens if you use one dot instead of two? A star?

Drakeo · 12-19-2008, 10:52 PM

what is the Burne shell http://www.injunea.demon.co.uk/pages/page203.htm the bigging to end

Simon Bridge · 12-19-2008, 11:02 PM

@Drakeo: who is your post addressed to? ... surely you mean "Bourne Shell"? We are using the Bourne-Again Shell, or BASH. I'm confused: would you please explain the relevance of the history lesson?

Drakeo · 12-20-2008, 12:18 AM

oh well your right I will stick to hardware. but it is all c to me hello world.

pixellany · 12-20-2008, 06:28 AM

Perhaps this was Drakeo's way of trying to help OP........

For topheraholic:
I suggest going to http://tldp.org and getting the Bash Guide for Beginners.

In regular expressions (regexes):

"." = any character
"*" = any number of the previous regex

The specific meaning of characters can change with context, so you have to look at the syntax for each specific command.

dhanyaelizabeth · 01-02-2009, 03:23 AM

Quote:

Originally Posted by topheraholic

stringZ=abcABC123ABCabc
echo `expr match "$stringZ" '$.[b-c]*[A-Z]..[0-9]$'` # abcABC1

you can see there is a "." and "*",what do they mean? why there is a . and * ?
thanks!

Google anyone?

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