为什么执行 echo `expr index "abcABC123ABCabc" 'Ca'`结果为1

jyhwn

为什么执行 echo `expr index "abcABC123ABCabc" 'Ca'`结果为1，而不是12

一直单念

just return the first index of any char in "string2" which matched in "string1", not the whole string in "string2".
because there is a char "a" in "Ca", so the returned index is 1.

jyhwn

Thank you! The expression is 'Numerical position in $string of first character in $substring that matches' in abs-guide-3.7 ,I think it has a mistake.

BEINGJESSE

echo `expr length "$string"`