Hi,

I have 20 tab delimited text files that have a common column (column 1). The files are named GSM1.txt through GSM20.txt. Each file has 3 columns (2 other columns in addition to the first common column).

I want to write a script to join the files by the first common column so that in the resulting output file, the first column is the common column that is present in all 20 files and the following sets of two columns after that are the last two columns of each text file (i.e. columns 2 and 3 are columns 2 and 3 of GSM1.txt, columns 4 and 5 are columns 2 and 3 of GSM 2.txt and so on...)

How do I go about doing that? Thanks!

join file1 file2 file3?

Actually I get the error message

join: extra operand `3.txt'


When I try

join 1.txt 2.txt 3.txt > output.txt

Check join man page; join can take only 2 files at a time. You'll need it run it in a loop or through xargs.

Thanks, I didn't realize that.

Okay then:

awk -F"\t" -v OFS="\t" 'F!=FILENAME { FNUM++; F=FILENAME }

{       COL[$1]++;        C=$1; $1="";        A[C, FNUM]=$0 }

END {
        for(X in COL)
        {
                printf("%s", X);
                for(N=1; N<=FNUM; N++) printf("%s", A[X, N]);
                printf("\n");
        }
}' file1 file2 file3 file4 ...

extend this to the number of files you have

join GSN1.txt GSN2.txt > tmp.tmp     
for f in GSN3.txt GSN4.txt GSN5.txt  
do                                   
    join tmp.tmp $f > tmpf           
    mv tmpf tmp.tmp                  
done                                 
mv tmp.tmp GSN_ALL.txt               
cat GSN_ALL.txt