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

Question

If I have the text in a shell variable, say $a:

a=\"The cat sat on the mat\"

How can I search for \"cat\" and return 4 using a

Answer 1

You can use grep to get the byte-offset of the matching part of a string:

echo $str | grep -b -o str

As per your example:

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

you can pipe that to awk if you just want the first part

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