search multiple patterns

Shell Programming and Scripting
1

I have two lists in a file that look like
a b
b a
e f
c d
f e
d c

I would like a final list
a b
c d
e f

I've tried multiple grep and awk but can't get it to work

2

grep can't do it because grep recalls nothing about previous lines. Even in awk you have to tell it to remember, which I do with the associative array A.

$ echo "a b
b a
e f
c d
f e
d c
" | awk '{
        # get a b order even if we get b a
        if($1 > $2) { tmp=$1; $1=$2; $2=tmp; }
        if(A[$1] != $2)  { print ; A[$1]=$2; }
}' | sort # sort is necessary for your example data, otherwise we get a b \n e f \n ...
a b
c d
e f
$
1 Like
3

Try this awk script which sorts each line and removes the dups...

awk '{
   n = split($0,a," ")
   for (i=1; i<n; i++)
     for (j=1; j<=n-i; j++)
       if (a[j] > a[j+1]) {
          t=a[j]
          a[j]=a[j+1]
          a[j+1]=t
       }
   for (i=1; i<=n; i++)
       v=sprintf("%s",v?v""a:a)
   if (v in x); else print $0
   x[v]=v; v=""
}' file
4

or Corona's solution in slightly different flavor:

awk '{
  if(a[$1]==$2 || a[$2]==$1) next; 
  a[$1]=$2;  print
}' data

comes out unsorted.

5

Don't know how the input file can look like but with the given example, the following works :

fold -w 1 inputfile | sort | uniq | xargs -n2

---------- Post updated at 12:25 AM ---------- Previous update was at 12:22 AM ----------

fold -w 1 inputfile | sort -u | xargs -n2
6

This would miss entries if you have multiple occurrences in one column:

$ cat data
a b
b a
e f
c d
f e
d c
a c
$ fold -w 1 data | sort | uniq | xargs -n2
a b
c d
e f
7

godzilla07 did not specify the criteria nor the logic needed to get the output of his example, so i am aware that the code i provide may not fit all cases, but i shot it as is since no futher constraints has been specified so far.

8

i didn't mean to be critical, just pointing out...

9

@mirni

No problem dude :smiley: