shell 字符串中定位字符位置 获取字符位置

${string:position}     #在$string中, 从位置$position开始提取子串
${string:position:length}     #在$string中, 从位置$position开始提取长度为$length的子串

Position of a string within a string using Linux shell script?

$a

a="The cat sat on the mat"

a="The cat sat on the mat"b=cat
strindex() {
x="${1%%$2*}"
[[ $x = $1 ]] && echo -1 || echo ${#x}
}
strindex "$a" "$b"   # prints 4
strindex "$a" foo    # prints -1

a="The cat sat on the mat"test="cat"
awk -v a="$a" -v b="$test" 'BEGIN{print index(a,b)}'

echo $a | grep -bo cat | sed 's/:.*$//'

echo $str | grep -b -o str

[user@host ~]$ echo "The cat sat on the mat" | grep -b -o cat
4:cat

echo $str | grep -b -o str | awk 'BEGIN {FS=":"}{print $1}'
echo $str | grep -b -o "cat" | cut -d: -f1

a="The cat sat on the mat"test="cat"
awk -v a="$a" -v b="$test" 'BEGIN{print index(a,b)}'