Nested for loops


 
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# 1  
Old 08-10-2011
Nested for loops

Greetings All,

The following script attempts to enumerate all users in all groups in the group file(GROUP) and echo the following information:

GROUP ---> USER

The script is as follows:

Code:
IFS=","
for GROUP in `ypcat -k group | cut -d" " -f1`
    do
        for USER in `ypcat -k group | grep $GROUP | cut -d":" -f4`
             do
                   echo "$GROUP -------> $USER"
             done
    done

The unexpected result is that the group name is only printed. It appears that the outer loop variable loses scope inside of the inner loop.

Any ideas on why this occurs is greatly appreciated.

Last edited by vbe; 08-11-2011 at 10:17 AM.. Reason: code tags
# 2  
Old 08-10-2011
Pardon me, I don't understand the question. The outer loop variable is $GROUP and you say that groupname gets printed, so how does " outer loop variable loses scope inside of the inner loop ". If it was losing scope, only $USER Will get printed.
# 3  
Old 08-10-2011
My apologies for the lack of clarity. I was thinking it was an issue with the $GROUP variable within the inner loop "for statement"(grep $GROUP):

for USER in `ypcat -k group | grep $GROUP | cut -d":" -f4`

I am new to bash scripting so I may be way off. When I run this the only output is the list of groups in the group file.
# 4  
Old 08-10-2011
Are you sure you want to set IFS to comma, since it affects the way the for loops are being evaluated: they will now iterate over elements separated by commas.
# 5  
Old 08-10-2011
Jack, try this, just one line, no for loops.
Code:
ypcat -k group|awk  -F:  '{for(i=4;i<=NF;i++) print $1 "--->" $i}'


Last edited by vbe; 08-11-2011 at 10:18 AM..
# 6  
Old 08-10-2011
Scrutinizer,

I was hoping that this would be useful in the comma delimited list of users resulting from the `ypcat -k group | grep $GROUP | cut -d":" -f4` output. Is there better way in bash to split a comma-delimited string of unknown length and loop through the results?

I am completely open to other easier methods of accomplishing this task.Smilie

---------- Post updated at 08:38 PM ---------- Previous update was at 08:13 PM ----------

@dude --- I want to provide more information on exactly what I am trying to accomplish. We are migrating to Centrify from a NIS environment. I want to be able to loop through all groups in the group file, extract each member and bounce it off of the AD groups to ensure that they are in sync.

So here is what I have so far:
Code:
IFS=","
for GROUP in `ypcat -k group | cut -d" " -f1`
        do
        for USER in `ypcat -k group | grep $GROUP | cut -d":" -f4`
            do
                if (adquery group -a $GROUP | grep $USER) then
                    echo "$USER is in $GROUP"
                else
                    echo "$USER not found"
                fi 
                       done
        done

Your suggestion looks pretty slick. Can I somehow modify it to accomplish the task at hand? Sorry I should have provided the background information earlier but my attempt to simplify the question actually complicated it.

Last edited by vbe; 08-11-2011 at 10:19 AM.. Reason: Please use code tags
# 7  
Old 08-10-2011
@dude2cool, I think you need an extra separator, no?
Code:
awk -F[:,] '{for(i=4;i<=NF;i++) if($i)print $1 "--->" $i}'

@jacksolm: in shell, you could try something like this:
Code:
oldIFS=$IFS
IFS=,
ypcat -k group | 
while IFS=: read group x x users
do
  for user in $users
  do
    echo "$group ---> $user"
  done
done
IFS=$oldIFS

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