如何在 shell 脚本中将此正则表达式与 grep 一起使用？

Question

I need to extract the public key in the shell script, Not sure how to use this. I am new to shell script. https://regex101.com/r/SXDEaU/1

Content of the file:

public_key=#STARTKEY#<public key base64 encoded>#ENDKEY#

Regex: /public_key=#STARTKEY#(.*)#ENDKEY#/s

Since the key is base64 encoded, it is a multiline string.

Desired output: <public key base64 encoded>

Answer 1

perl -M5.010 -0777ne'say for /public_key=#STARTKEY#(.*)#ENDKEY#/s' file

Answer 2

With awk using its RS variable and setting it to paragraph mode please try following code.

awk -v RS= 'match($0,/public_key=#STARTKEY#.*#ENDKEY#/){print substr($0,RSTART+21,RLENGTH-29)}'  Input_file

Answer 3

Using sed :

sed -En 's/.*#STARTKEY#(.*)#ENDKEY#/\1/p' file

Answer 4

A little trick that uses # as delimiter for reading the key in pure bash:

IFS='#' read -d '' _ _ key _ < key.txt

printf '%s\n' '${key//$'\n'/}"