SED命令与正则表达式匹配，但不能替代

Question

I am working on building a .sed file to start scripting the setup of multiple apache servers. I am trying to get sed to match the default webmaster email addresses in the .conf file which works great with this egrep. However when I use sed to try and so a substitute search and replace i get no errors back but it also does not do any substituting. I test this by running the same egrep command again.

egrep -o '\b[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+(\.[A-Za-z]{2,4})?\b' /home/test/httpd.conf

returns

admin@your-domain.com
root@localhost
webmaster@dummy-host.example.com

The sed command I'm trying to use is

sed -i '/ServerAdmin/ s/\b[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+(\.[A-Za-z]{2,4})?\b/MY_ADMIN_ADDRESS@gmail.com/g' /home/test/httpd.conf

After running I try and verify the results by running the egrep again and it returns the same 3 email address indicating nothing was replaced.

Answer 1

Don't assume that any two tools use the same regular expression syntax. If you're going to be doing replacements with sed , use sed to test - not egrep . It's easy to use sed as if it were a grep command: sed -ne '/pattern/p' .

Answer 2

sed must be told that it needs to use extended regular expressions using the -r option then making the sed command as follows.

sed -ir '/ServerAdmin/ s/\b[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+(\.[A-Za-z]{2,4})?\b/MY_ADMIN_ADDRESS@gmail.com/g' /home/test/httpd.conf

Much thanks to Kent for pointing out that the address it was missing wasnt following a ServerName