Using Sed command to search and replace text in XML file or any other file .
To replace entire line with a specific text/string in linux by using sed command
Syntax:
sed -i 's/.*<TEXT>.*/<TEXT TO BE ON REPLACED LINE>/' *.xml
Replace below placeholders completely to put your required string/text in above syntax.
<TEXT>
<TEXT TO BE ON REPLACED LINE>
Please be aware of the escape sequence while executing the command.
eg. Here I am replacing entire line which contains <lastmod> tag with <lastmod>2017-07-19T15:09:05+08:00</lastmod>
So please see that closing </lastmod> tag is having `\` (escape sequence). In you case it may vary depending upon your requirement.
sed -i 's/.*<lastmod>.*/<lastmod>2017-07-19T15:09:05+08:00<\/lastmod>/' *.xml
Be specific to the syntax and consider each and every comma and other preposition.