Question

Q1:
I would like to edit a file containing a set of email ids such that all the domain names become generic.

Example,
[e-mail]
[e-mail]
[e-mail]

to
[e-mail]
[e-mail]
[e-mail]

I used the following sed cmd to replace @ with _

sed 's/@/_/' <filename>

Is there a way to append another sed cmd to the cmd mentioned above such that I can replace the last part of the domain names with @generic.com?

Q2:
so how do I approach this if I had text at the end of my domain names?

Example,
[e-mail],i am peter
[e-mail],i am also peter

To,
[e-mail],i am peter
[e-mail],i am also peter

I tried @(,) instead of @(.*)
it doesn’t work and I cant think of any other solution

Q3:
Suppose if my example is like this,

[e-mail]
[e-mail],i am peter

I want my result to be as follows,

[e-mail]
[e-mail],i am peter,i am peter

How do i do this with a single sed cmd?

The following cmd would result in,

sed -r 's!@(.*)!_\[e-mail]!' FILE

[e-mail]
peter_hotmail.co.in,i am peter,i am [e-mail]

And the following cmd wont work on “[e-mail]”,

sed -r 's!@(.*)(,.*)!_\[e-mail]!' FILE

Thanks!!

Answer 1

Golfing =)

$ cat FILE
Example,
[e-mail]
[e-mail]
[e-mail]

$ sed -r 's!@(.*)!_\[e-mail]!' FILE
Example,
[e-mail]
[e-mail]
[e-mail]

In reply to user1428900, this is some explanations :

sed -r          # sed in extended regex mode
s               # substitution
!               # my delimiter, pick up anything you want instead !part of regex
@(.*)           # a literal "@" + capture of the rest of the line
!               # middle delimiter
_\[e-mail] # an "_" + the captured group N°1 + "@generic.com"
!               # end delimiter
FILE            # file-name

Extended mode isn’t really needed there, consider the same following snippet in BRE (basic regex) mode :

 sed 's!@\(.*\)!_\[e-mail]!' FILE

Edit to fit your new needs :

$ cat FILE
Example,
[e-mail],I am peter
[e-mail]
[e-mail]


$ sed -r 's!@(.*),.*!_\[e-mail]!' FILE
Example,
[e-mail]
[e-mail]
[e-mail]

If you want only email lines, you can do something like that :

sed -r '/@/s!@(.*),.*!_\[e-mail]!' FILE

the /@/ part means to only works on the lines containing the character @

Edit2:

if you want to keep the end lines like your new comments said :

sed -r 's!@(.*)(,.*)!_\[e-mail]\2!' FILE