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Old 09-21-2008, 01:55 PM   #1
basildon
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Registered: Sep 2008
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Checking whether a variable is alphabetic


Hi

I used this snippet of code to test whether a variable contains solely alphabetic characters.

case $var in
[A-Za-z]) echo "alpha"
;;
*) echo "not alpha "
;;
esac

Testing the $var with all alphabetic characters resulted in the "not alpha" outcome

Could anyone please advise what is wrong?

Thanks
 
Old 09-21-2008, 02:26 PM   #2
animeshsaxena
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Registered: May 2007
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Quote:
Originally Posted by basildon View Post
Hi

I used this snippet of code to test whether a variable contains solely alphabetic characters.

case $var in
[A-Za-z]) echo "alpha"
;;
*) echo "not alpha "
;;
esac

Testing the $var with all alphabetic characters resulted in the "not alpha" outcome

Could anyone please advise what is wrong?

Thanks
Everything is correct, but you are writing the regex for one character.

[A-Za-z] will match a single character, so when you type a string it won't match. Change the regex to [A-Za-z]*

* ---> More than one character or combinations of this.....for more info...check out regular expressions.
 
Old 09-21-2008, 03:53 PM   #3
theYinYeti
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Registered: Jul 2004
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Code:
if [ "${var//[a-zA-Z]/}" == "" ]; then
  echo only alpha
else
  echo not only alpha
fi
Yves.
 
Old 09-21-2008, 04:00 PM   #4
H_TeXMeX_H
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Also, I would use '[:alpha:]' instead of '[A-Za-z]', it's more portable across character sets / encodings.
 
Old 09-21-2008, 04:03 PM   #5
theYinYeti
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Good to know. I knew this for regex, but I didn't know this could apply to shell patterns.

Yves.
 
  


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