Position character position in shell string to get character position

Linux shell String Operations (length, find, replace) detailed

The following two string operations are described in this blog post,

1 ${string:p osition}     #在 $string, extract substring 2 ${string starting from position $position :  Position:length}     

View Code

The location of the character/substring in the parent string is required (position), and the shell string does not provide an interface for the location of the substring, and if the operation is based on a string variable, the location of the substring cannot be predicted;

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

The article mentions some solutions that feel valuable and reproduced as follows:

If I has 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 Linux shell script, or-1 if not found?

1.

With bash

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

ShareImprove this answer2.

I used awk for this

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

3.

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

4.

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:

[[email protected] ~]$ echo "The cat sat on the mat" | grep -b -o cat4:cat

You can pipe this to awk if you just want the first part

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

5 down vote

I used awk for this a="The cat sat on the mat"test="cat"awk -v a="$a" -v b="$test" ‘BEGIN{print index(a,b)}‘

Position character position in shell string to get character position