Hi. I have a file which looks like this. It has two fields which are separated by a '+' sign. 

d_145_1_2- + c_3_1_8-e_74_1_1-
a_100_1_6-c_2_1_6- + b_50_1_2-
c_69_1_17- + b_61_6_1-
c_2_1_2- + a_123_1_1-
d_83_1_1- + c_2_1_5-d_162_1_1-
c_2_1_2- + a_123_1_1-
a_123_1_1- + c_2_1_2-

[download]

What I need to do is to extract out lines which are unique in this file. For example here,from the snippet of the file above, the following lines are unique: 

d_145_1_2- + c_3_1_8-e_74_1_1-
a_100_1_6-c_2_1_6- + b_50_1_2-
c_69_1_17- + b_61_6_1-
c_2_1_2- + a_123_1_1-
d_83_1_1- + c_2_1_5-d_162_1_1-

[download]

One shall notice that the fields a_123_1_1- and c_2_1_2- occur as a pair more than once, however in such a way that their relative order is reversed. Is there anyway I can extract out unique lines, keeping only one occurrence of such pairs i.e. a_123_1_1- and c_2_1_2-? I have as of now tried awk. There, I was unable to retrieve unique lines using the uniq function as that doesn't take care of the same combinations of fields repeating in reverse orders. Also I tried merging the two fields together and then carrying out awk operations but to no avail. Is there any way such that perl makes the job easier?

In reply to xtracting unique lines by anasuya

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