sed

[addle_brains]

Anybody actually understand how to use sed? I need to create a script that will output the user name, user ID, group ID and home directory of each user in the /etc/passwd file. I've been trying for a few hours but i'm getting lost amongst the delimiting ( with : ) and all the rest.

 

[Camper]

I have always used sed as a find and replace tool. I would use awk command to grab the information your looking for.
EX. cat /etc/passwd | awk -F":" '{printf("User name %s UserID %s GroupID %s HomeDir %s.\n", $1, $3, $4, $6)}'
Or something like that. I'm not around a Linux computer to test.
http://www.ss64.com/bash/gawk.html

 

[addle_brains]

Thanks, i'd like to avoid using awk. seeing as the passwd file is uses colon delimiting, i didn't think it would be too hard to grab each element and then only output 1, 3, 4, 6. I can't figure it out though.

 

[Camper]

The -F":" switch sets awk to a comma delimited.
I tested it on my pc it works like a charm.

Edit: Here is a web page that shows how to use sed. Many Examples!!!
http://www.grymoire.com/Unix/Sed.html

 

[addle_brains]

Hey, I managed to do it with just sed:

cat /etc/passwd | sed "s/\(.*\):\(.*\):\(.*\):\(.*\):\(.*\):\(.*\):\(.*\)/\1 \3 \4 \6/"

only problem is formatting the output... if i add tabstops in there, it works, except for a few user names that are too long the formatting goes askew. Is there are way to fix this?

 

[Camper]

Nice job. As for the rest your jumping out of my league.

 

[addle_brains]

Hehe. The confusing part is esaping (\) the parenthesis. You tend to get lost with so many characters in there. Not to worry, I think the stdout formatting is out of my league (i can do it in c++, but that's overkill for this kind of thing).

Thanks for your help.