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Shell Programming and Scripting

who - uniq output

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# 1  
Old 10-24-2008
who - uniq output
Hi,
I'd like to have a script what takes the 'who' output and grabs the user names and outputs just the user name, and no duplicates.

I know I could do something like:

who | awk '{print $1}' | uniq -u

but I'd like to stay away from using the 'uniq' comand and just use awk.

Thanks
# 2  
Old 10-24-2008
Tools Perhaps someone might clean this up a bit
The following works, but not sure if all necessary.

Code:
#! /usr/bin/bash

who | awk '{line[$1] = $1
     sum[$1]++}
    END{
     for(i in sum)
     if (sum[i]>0)
       print line[i]
}'

set array variable to the first read (which is name) field
increment a counter so I can know if anything in array value

step thru all values in my sum array
if the value in sum > 0 (meaning I have a match)
print out the corresponding entry in the line array
Last edited by joeyg; 10-24-2008 at 05:17 PM.. Reason: added some explanation
# 3  
Old 10-24-2008
Or:

Code:
who | awk '!($1 in a){a[$1];print $1}'

Regards
# 4  
Old 10-24-2008
thats awesome, thanks to the both of you Smilie

How about excluding 'root' from the output?
# 5  
Old 10-24-2008
Code:
who | awk '!($1 in a) && !/root/{a[$1];print $1}'

# 6  
Old 10-24-2008
Tools
Excluding root

Code:
> cat uniq_names
#! /usr/bin/bash

who | awk '$1!~"root" {line[$1] = $1
     sum[$1]++}
    END{
     for(i in sum)
     if (sum[i]>0)
       print line[i]
}'

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