匹配一個Regex的Shell

is_upper()
# is_upper
# checks tosee if we have a string in upper case
# to call: is_upper $1
{
# check we have the right params
if [ $# -ne 1 ]; then
echo "is_upper: I need a string to test OK"
return 1
fi
# use awk to check we have only uppercase
_IS_UPPER=`echo $1|awk '{if($0~/[^A-Z]/) print "1"}'`
if [ "$_IS_UPPER" != "" ]
then
# no, they are not all uppercase
return 1
else
# yes all uppercase
return 0
fi
}

#_IS_UPPER=`echo $1|awk '{if($0~/[^A-Z]/) print "1"}'`這句的“ ~ ”表示匹配一個Regex，[^A-Z]表示A-Z以外的字元 
所以這句話的意思是如果第一參數中出現了任意一個A-Z以外的字元(即不全是大寫英文字母)，則列印"1"