Escape multiple dots in variable

Question

Suppose i have a variable $email whose value is stack.over@gmail.com.I want to add a \ before every dot except the last dot and store it in a new variable $email_soa.

$email_soa should be stack\.over@gmail.com in this case.

Answer 1

sed -E 's/\./\\\./g;s/(.*)\\\./\1\./'

should do it.

Test

$ var="stack.over@flow.com"
$ echo $var | sed -E 's/\./\\\./g;s/(.*)\\\./\1./'
stack\.over@flow.com
$ var="stack.over@flow.com."
$ echo $var | sed -E 's/\./\\\./g;s/(.*)\\\./\1./'
stack\.over@flow\.com.

Note

The \\ makes a literal backslash and \. makes a literal dot

Answer 2

You can use gawk:

var="stack.over@gmail.com"
gawk -F'.' '{OFS="\\.";a=$NF;NF--;print $0"."a}' <<< "$var"

Output:

stack\.over@gmail.com

Explanation:

• -F'.' splits the string by dots
• OFS="\\." sets the output field separator to \.
• a=$NF saves the portion after the last dot in a variable 'a'. NF is the number of fields.
• NF-- decrements the field count which would effectively remove the last field. This also tells awk to reassemble the record using the OFS This feature does at least work with GNU's gawk.
• print $0"."a prints the reassmbled record along with a dot and the value of a

Answer 3

You could use perl to do this:

perl -pe 's/\.(?=.*\.)/\\./g' <<<'stack.over@gmail.com'

Add a slash before any dots that have a dot somewhere after them in the string.

Answer 4

How about this:

temp=${email%.*}
email_soa=${temp/./\\.}.${email##*.}