UNIX for Dummies Questions & Answers

Hi All,
I am fairly new to the world of Unix, and I am looking for a way to replace a line of text in a file with a delimited array of values.
I have an aliases file that is currently in use on our mail server that we are migrating off of. Until the migration is complete, the server must stay up. I need to migrate approximately 50 people per day. In order to do this, I must replace lines in my aliases file without disturbing the distribution lists.
For example, I have a list of users as such:
user1: id1
user2: id2
user3: id3
user4: user2
distributionlist: user1,user3
I want to search that file based on the id# and comment that line out. I then want to insert a line directly underneath it as such:
#user1: id1
user1: alias1@domain.com
The domain is not static, and that is why I would need to reference an array (tab delimited or such).
I would prefer to create a backup of the original file with a rather than output to a new filename as I think this may be easier than changing the script that puts the file into production.
I know this probably isn't the best explanation and I may be missing some info. Thanks in advance!

so you have these files:

Code:

file1

user1: id1
user2: id2
user3: id3
user4: user2
distributionlist: user1,user3

file2 

user1: alias1@domain.com

expect output:

#user1: id1
user1: alias1@domain.com
user2: id2
user3: id3
user4: user2
distributionlist: user1,user3

Confirm first.

That is very close, but to avoid issue I am probably going to have file 2 as:
id1: alias1@domain.com
I want to avoid any possibility that we would accidentally edit a distribution list which may contain a "user#" entry, since the "id#" value is going to be unique.

Something like this?

Code:

awk -F": " '
NR==FNR{a[$1]=$2; next} 
a[$2]{$0= "#" $0 RS $1 FS a[$2]}
1' file2 file1

That looks like it is on the right track. I tried it with a couple test files, but it didn't do what it was supposed to.
I think you may need a bit more info about the file. After each : there is a tab, not a space. Some times there are two tabs, sometimes there is a space after the tab, but each : should be immediately followed by at least a tab.

I really appreciate the assistance. Thanks!

Try this:

Code:

awk -F":[ \t]+" '
NR==FNR{a[$1]=$2; next} 
a[$2]{$0= "#" $0 RS $1 ": " a[$2]}
1' file2 file1

I have tried the adjusted code but have not had any luck on my test files. It doesn't seem to be doing the editing, but it does appear to go through the file.
If you could explain what each item is doing, I may be able to figure this out with a little more assistance.

Thanks again!