sed

addle_brains · 10-04-2007, 05:54 PM

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 · 10-04-2007, 08:21 PM

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 · 10-04-2007, 11:21 PM

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 · 10-06-2007, 01:41 AM

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 · 10-07-2007, 01:17 PM

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 · 10-08-2007, 03:47 AM

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

addle_brains · 10-08-2007, 02:17 PM

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.

10-04-2007, 05:54 PM	#1 (permalink)
addle_brains Gold Member Join Date: Feb 2007 Location: Highfields, QLD, Australia Posts: 304	sed 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. __________________ ASUS P5K Deluxe /Wifi API Intel Core2 Duo E6750@3.37GHz 2 x 1Gig 667 RAM Inno3D iChill Nvidia 8600GTS XStriker3 2 x Seagate 250Gig SATA HD Samsung DVD-RAM Thermaltake Beetle CPU cooler Thermaltake 850watt Toughpower CoolerMaster Mystique Silver Aluminium Case

10-04-2007, 08:21 PM	#2 (permalink)
Camper Diamond Member Join Date: Mar 2005 Location: /dev/null Age: 22 Posts: 1,227	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 __________________ Dell Inspiron 530 Q6600 Quad 3gb RAM Nvidia 8600 GT 500GB HD

10-04-2007, 11:21 PM	#3 (permalink)
addle_brains Gold Member Join Date: Feb 2007 Location: Highfields, QLD, Australia Posts: 304	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. __________________ ASUS P5K Deluxe /Wifi API Intel Core2 Duo E6750@3.37GHz 2 x 1Gig 667 RAM Inno3D iChill Nvidia 8600GTS XStriker3 2 x Seagate 250Gig SATA HD Samsung DVD-RAM Thermaltake Beetle CPU cooler Thermaltake 850watt Toughpower CoolerMaster Mystique Silver Aluminium Case

10-06-2007, 01:41 AM	#4 (permalink)
Camper Diamond Member Join Date: Mar 2005 Location: /dev/null Age: 22 Posts: 1,227	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 __________________ Dell Inspiron 530 Q6600 Quad 3gb RAM Nvidia 8600 GT 500GB HD Last edited by Camper; 10-06-2007 at 02:54 AM.

10-07-2007, 01:17 PM	#5 (permalink)
addle_brains Gold Member Join Date: Feb 2007 Location: Highfields, QLD, Australia Posts: 304	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? __________________ ASUS P5K Deluxe /Wifi API Intel Core2 Duo E6750@3.37GHz 2 x 1Gig 667 RAM Inno3D iChill Nvidia 8600GTS XStriker3 2 x Seagate 250Gig SATA HD Samsung DVD-RAM Thermaltake Beetle CPU cooler Thermaltake 850watt Toughpower CoolerMaster Mystique Silver Aluminium Case

10-08-2007, 03:47 AM	#6 (permalink)
Camper Diamond Member Join Date: Mar 2005 Location: /dev/null Age: 22 Posts: 1,227	Nice job. As for the rest your jumping out of my league. __________________ Dell Inspiron 530 Q6600 Quad 3gb RAM Nvidia 8600 GT 500GB HD

10-08-2007, 02:17 PM	#7 (permalink)
addle_brains Gold Member Join Date: Feb 2007 Location: Highfields, QLD, Australia Posts: 304	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. __________________ ASUS P5K Deluxe /Wifi API Intel Core2 Duo E6750@3.37GHz 2 x 1Gig 667 RAM Inno3D iChill Nvidia 8600GTS XStriker3 2 x Seagate 250Gig SATA HD Samsung DVD-RAM Thermaltake Beetle CPU cooler Thermaltake 850watt Toughpower CoolerMaster Mystique Silver Aluminium Case

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