[SOLVED] checking a string

bayanaa · 05-17-2012, 04:19 AM

Hello for all

How can I check if a string has a separator among the characters like backspace ' ' or ','

My best regards

pan64 · 05-17-2012, 04:32 AM

please specify at least a language, what is the separator...
Otherwise you will get an answer like this: just read it!

colucix · 05-17-2012, 04:39 AM

Hi and welcome to LinuxQuestions!

If you want to check for punctuation or spaces characters in general, you can use grep with the -E option and specify the proper character classes, e.g.

Code:

$ echo string | grep -E -q '[[:punct:]]|[[:space:]]' && echo yes || echo no
no
$ echo str,ing | grep -E -q '[[:punct:]]|[[:space:]]' && echo yes || echo no
yes

just to give you an idea. If you want to check for specific characters only, include them in a character list and eventually use the shell octal notation for special or control characters. For example to match a single backspace or space or comma:

Code:

$ echo string | grep -E $'\010''|[ ,]'

The part in blue is the shell notation for octal codes and it must be left outside the quotes that embed the rest of the grep pattern. Hope this helps.

bayanaa · 05-17-2012, 08:20 AM

Amazing
Thanks a lot

You've mentioned punct as a name of ,
But, what is the name of : symbol

again thank you a lot

Quote:

Originally Posted by colucix

Hi and welcome to LinuxQuestions!

If you want to check for punctuation or spaces characters in general, you can use grep with the -E option and specify the proper character classes, e.g.

Code:

$ echo string | grep -E -q '[[:punct:]]|[[:space:]]' && echo yes || echo no
no
$ echo str,ing | grep -E -q '[[:punct:]]|[[:space:]]' && echo yes || echo no
yes

just to give you an idea. If you want to check for specific characters only, include them in a character list and eventually use the shell octal notation for special or control characters. For example to match a single backspace or space or comma:

Code:

$ echo string | grep -E $'\010''|[ ,]'

The part in blue is the shell notation for octal codes and it must be left outside the quotes that embed the rest of the grep pattern. Hope this helps.

colucix · 05-17-2012, 08:35 AM

Actually [:punct:] is the name of a character class in the POSIX standard. It comprises all the punctuation characters. Here is a complete list.

David the H. · 05-18-2012, 08:02 AM

I noticed you never answered pan64's questions. If you would provide more details about what you are doing, there may be better options than grep. The shell itself can easily check for the existence of characters in a string, for example:

Code:

string='foo,bar,baz'

# if bash or ksh:

if [[ $string == *,* ]]; then
	echo 'contains commas'
else
	echo "doesn't contain commas"
fi

# fully portable version

case $string in

	*,*) echo 'contains commas' ;;

	  *) echo "doesn't contain commas" ;;

 esac