Character Class ?

[polar1]

I am having a problem understanding how the character classes work using Posix. I am trying to extract a single digit from a string as follows:
rowa='1 2 3 4 5'
rowb=`echo $rowa |awk '{print $1,$2,$3,$4}'
for i in "$rowb
do
if [ "${i+[3[:digit:]}" = "3" ] # <- This returns1! Syntax problem!
then
echo "$i"
fi
done

 

[cptk]

polar1 -
I'm not clear exactly on what you're goal is, could you be more specific?

Anyway, for starters ...
1.) your rowa & rowb variables are identical
2.) you're missing a [ and a backtic `

Also, try this:
for i in $rowb
do
if [`echo $i | /usr/xpg4/bin/egrep [[:digit:]]` = 3 ]
then
echo $i
done

 

[polar1]

Thanks CPTK for your help. Sorry for the typo's.
My thoughts were to extract a single digit from rowa to test its value, (1|2|3|4|5)
The character class was confusing.