On Thursday 29 January 2004 19:14, Ben Yau wrote:

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From: Jeff Kinz [mailto:jkinz@kinz.org] Sent: Thursday, January 29, 2004 9:33 AM To: suse-linux-e@suse.com Subject: Re: [SLE] how to change users home directories

On Thu, Jan 29, 2004 at 06:18:40PM +0000, steve-ss wrote:

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I want to change a bunch of users home directories from /home

and move them

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to /home/year7 but I want the username, password and directory

content to

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remain the same. I can edit /etc/passwd and change to the new

directory but

...

how do I make the changes take effect? Unfortunately I can't

use yast to do

...

this. Thanks, Steve.

something like:

cd /homr for file in *; do if [ ! -e year7 ] ; then mkdir year7 fi mv $file year7/. done

then edit /etc/passwd

Could you help explain the script ? the "for file in *" seems like it would move every username in /home to /home/year7 ?

(why not just do: cd /home; make year7; mv * year7/ ) ? I am probably reading your script wrong so if you could help out that'd be awesome.

Anyway, if the OP only wants to move specified accounts and not everyone in /home, here is another possible way

edit the /etc/passwd file first. Change the /home dirs. assuming "year7" only shows up in your /etc/passwd file for those users whose accounts are in /home/year7/[username] (e.g. there is no username "year7" or somehting like that).

(grep year7 passwd | awk -F: '{print "mv /home/"$1" /home/year7/"$1}') | cat

This will print out what the script is going to do. If it looks good, you can then redirect to a file and run as a shell script OR change "cat" to "/bin/sh" or "/bin/bash" and it will then do the actual "mv "commands.

Ben

Hi and thanks for the tips. I changed it to: (grep year7 /etc/passwd | awk -F: '{print "mv /home/"$1" /home/year7/"$1}') | cat I don't understand it but it runs OK. Is there a quick one liner to explain how it works? Thanks again, Steve.

On Thursday 29 January 2004 21:56, steve-ss wrote:

(grep year7 /etc/passwd | awk -F: '{print "mv /home/"$1" /home/year7/"$1}') | cat I don't understand it but it runs OK. Is there a quick one liner to explain how it works? Thanks again, Steve.

Okay, here we go [afaik :)] grep is a powerful pattern matching utility: #grep year7 /etc/passwd goes through the file /etc/passwd and looks for the string "year7" and prints it to "stdout" [i.e. standard output so other programs can process the info, or display on screen] The " | " is known as a pipe through - basically, run the program to the left and feed the output to the program on the right. awk is like grep iirc, but more powerful. the -F: runs a program, and the stuff after that in the apostrophes is the program itself. It prints: mv /home/ The $1 indicates take the first field from the output line from the previous program and insert it here, so if your paswd file had "bob" as the first field, then it would print "mv /home/bob" :) If you follow in the same vein for the rest of it, then you get: mv /home/firstfield /home/year7/firstfield then the lot is "piped through" cat which just displays it to the screen [like "type" on dos/windows] Hopefully I haven't confused you more :g: Jon

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grep is a powerful pattern matching utility:

#grep year7 /etc/passwd goes through the file /etc/passwd and looks for the string "year7" and prints it to "stdout" [i.e. standard output so other programs can process the info, or display on screen] The " | " is known as a pipe through - basically, run the program to the left and feed the output to the program on the right.

awk is like grep iirc, but more powerful. the -F: runs a program, and the stuff after that in the apostrophes is the program itself. It prints: mv /home/ The $1 indicates take the first field from the output line from the previous program and insert it here, so if your paswd file had "bob" as the first field, then it would print "mv /home/bob" :)

If you follow in the same vein for the rest of it, then you get: mv /home/firstfield /home/year7/firstfield

then the lot is "piped through" cat which just displays it to the screen [like "type" on dos/windows]

Hopefully I haven't confused you more :g:

Jon

Now THIS is what i like!!! A short description what the fix/scrip/sollution does. It helps us illiterates to understand whats going on. I usaly dont run unexplained/undocumented scripts unless i get a halfdecent understanding of what it does. The way Jon explained the script is exemplary!

VERY GOOD WORK!!

Rikard, I also replied to this with something similar but heaven knows where that mail is sitting now ... Only one correction... the -F: actully tells awk to use the : character as a field seperator (as opposed to a space character that we normally use). Awk is way more powerful than grep. Iif you can find out what the initials AWK stand for then that'll give you a clue why. Damian

On Friday 30 January 2004 12:07, Damian O'Hara wrote:

Only one correction... the -F: actully tells awk to use the : character as a field seperator (as opposed to a space character that we normally use). Ahhh :) Thank you! I will add that to my reference list :g:

I am just trying to think what program I got that switch confused with.. hrmm... *thinks*.

Awk is way more powerful than grep. Iif you can find out what the initials AWK stand for then that'll give you a clue why. I thought they were the initials of the founders of that proggie? I shall do some research methinks :)

Thank you for the correction to my explanation Damian - I appreciate it :) Jon

On Friday 30 January 2004 16:17, Ben Yau wrote:

...

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(grep year7 passwd | awk -F: '{print "mv /home/"$1" /home/year7/"$1}') | cat

This will print out what the script is going to do. If it

looks good, you

...

can then redirect to a file and run as a shell script OR change "cat" to "/bin/sh" or "/bin/bash" and it will then do the actual "mv "commands.

Ben

Hi and thanks for the tips. I changed it to:

(grep year7 /etc/passwd | awk -F: '{print "mv /home/"$1" /home/year7/"$1}') | cat

Good idea on the "/etc/passwd". Not a quick one liner explanation, but here is a brief explanation. If you do a man on grep and awk, you will get the complete info . The short version is:

grep searchstring file

will look in "file" and print out every line that has searchstring in it. There are a lot of args you can use (case sensitive, etc.).

The | is a pipe . It will use the standard output of the previous command as standard input of the next command

awk '{print $1}'

on it's own will print out the first column of the output using whitespace as a delimiter. to print out the second column, use $2, third column $3, and last column $NF. I usually use awk as part of a pipe. For example:

# echo "col1 col2 col3" | awk '{print $1}' col1 # echo "col1 col2 col3" | awk '{print $2}' col2 # echo "col1 col2 col3" | awk '{print $NF}' col3 #

To change the delimiter from white space to something else, use -F option followed by the character you want as a delimiter. In the case of /etc/passwd, we want to use the colon as the delimiter. Try the below to see what you get.

cat /etc/passwd | awk -F: '{print $1}' cat /etc/passwd | awk -F: '{print $2}' cat /etc/passwd | awk -F: '{print $NF}'

(Note: similar to how you can specify a filename in the "grep" command, you can do the same thing with awk. cat /etc/passwd | awk -F: '{print $1}'

and

awk -F: '{print $1}' /etc/passwd

will give the same results.

Now the print utility is very strong in awk. You can specify other strings to print out literally with the double quote. Anything in double quotes is printed out. So you can print out

echo "file1 file2" | awk '{print "mv "$1" to "$file2}'

The trickiest part of awk and printing is keeping track of your double quotes. That's the basics.

Hope that helps.

Utterly and 100%'ly. You guys have saved me so much time. Next round on me. Cheers, Steve.