1.install libheif-examples

sudo apt-get install libheif-examples

2.Convert subfolder *.HEIF to .jpg

for file in *.HEIC; do heif-convert $file ${file/.HEIC/.jpg}; done

將同一目錄下，所有副檔名為「.HEIC」的檔案，用 heif-convert 程式轉為同檔名，但副檔名為「 .jpg」 的 JEPG 格式圖檔。

for file in *.HEIC; do heif-convert $file ${file/%.HEIC/.jpg}; done

將同一目錄下，所有檔名結尾副檔名為「.HEIC」的檔案，用 heif-convert 程式轉為同檔名，但副檔名為「 .jpg」 的 JEPG 格式圖檔。

參考：

1.https://askubuntu.com/questions/958355/any-app-on-ubuntu-to-open-and-or-convert-heif-pictures-heic-high-efficiency-i

2.Replace one substring for another string in shell script

3.Shell Script 字串搜尋並取代

搜尋取代變數的字串:

#!/bin/sh
 
str="hello_abc"
 
echo ${str/abc/xyz

man bash 手冊中 ${parameter/pattern/string} 說明

${parameter/pattern/string}

${parameter/pattern/string} Pattern substitution.  
The pattern is expanded to produce a pattern just as in pathname expansion.  Parameter is expanded and the longest match of pattern  against  its value  is  replaced  with  string.   
If  pattern begins with /, all matches of pattern are replaced with string.  
Normally only the first match is replaced.  
If pattern begins with #, it must match at the beginning of the expanded value of parameter.  
If pattern begins with %, it must match at the end of the expanded value  of  parameter.   
If  string  is null, matches of pattern are deleted and the / following pattern may be omitted.  
If parameter is @ or *, the substitution operation is applied to each positional parameter in turn, and the expansion is the resultant list.  
If parameter is an array variable subscripted with @ or *, the  substitution  operation  is applied to each member of the array in turn, and the expansion is the resultant list.

更多範例：

first="I love Suzy and Mary"
second="Sara"
first=${first/Suzy/$second}

That will replace only the first occurrence; to replace them all, double the first slash:

first="Suzy, Suzy, Suzy"
second="Sara"
first=${first//Suzy/$second}
# first is now "Sara, Sara, Sara"