match values in first column of two files and join the matching lines in a new file

Question

I need to find matches with the string in column 1 ($1) in file1.txt with the string in column 1 ($1) in file2.txt. Then I want to join the lines where there was a match in a new file.

cat file1.txt
1050008 5.156725968 8.404038296 124.9198605 3.23E-21    2.33E-17    38.57865782
3310747 5.631470026 8.581936875 124.6039122 3.34E-21    2.33E-17    38.55204806
5910451 4.900364671 8.455329195 124.5720603 3.35E-21    2.33E-17    38.54935989
730156  5.565210738 8.48792701  122.2168789 4.28E-21    2.33E-17    38.34773989

cat file2.txt
4230037 ILMN Controls   ILMN_Controls   ERCC-00071  ILMN_333646 ERCC-00071  ERCC-00071
1050008 ILMN Controls   ILMN_Controls   ERCC-00009  ILMN_333584 ERCC-00009  ERCC-00009
5260356 ILMN Controls   ILMN_Controls   ERCC-00053  ILMN_333628 ERCC-00053  ERCC-00053
3310747 ILMN Controls   ILMN_Controls   ERCC-00144  ILMN_333719 ERCC-00144  ERCC-00144
5910451 ILMN Controls   ILMN_Controls   ERCC-00003  ILMN_333578 ERCC-00003  ERCC-00003
1710435 ILMN Controls   ILMN_Controls   ERCC-00138  ILMN_333713 ERCC-00138  ERCC-00138
1400612 ILMN Controls   ILMN_Controls   ERCC-00084  ILMN_333659 ERCC-00084  ERCC-00084
730156  ILMN Controls   ILMN_Controls   ERCC-00017  ILMN_333592 ERCC-00017  ERCC-00017

I would like the output file to look like this:

out.txt
1050008 5.156725968 8.404038296 124.9198605 3.23E-21    2.33E-17    38.57865782 1050008 ILMN Controls   ILMN_Controls   ERCC-00009  ILMN_333584 ERCC-00009  ERCC-00009
3310747 5.631470026 8.581936875 124.6039122 3.34E-21    2.33E-17    38.55204806 3310747 ILMN Controls   ILMN_Controls   ERCC-00144  ILMN_333719 ERCC-00144  ERCC-00144
5910451 4.900364671 8.455329195 124.5720603 3.35E-21    2.33E-17    38.54935989 5910451 ILMN Controls   ILMN_Controls   ERCC-00003  ILMN_333578 ERCC-00003  ERCC-00003
730156  5.565210738 8.48792701  122.2168789 4.28E-21    2.33E-17    38.34773989 730156  ILMN Controls   ILMN_Controls   ERCC-00017  ILMN_333592 ERCC-00017  ERCC-00017

The files are tab delimited and have missing values in some columns.

There is 31 columns in file2.txt and >47000 lines and I'm trying to do this in bash (OSX)

If you have a solution I would greatly appreciate if you could briefly explainn the steps as I'm very new to this.

Answer 1

If you don't mind the output being ordered by the first column then you can use this invocation of the join command:

join <(sort file1.txt) <(sort file2.txt) >out.txt

Answer 2

awk 'BEGIN {
  FS = OFS = "\t"
  }
NR == FNR {
  # while reading the 1st file
  # store its records in the array f
  f[$1] = $0
  next
  }
$1 in f {
  # when match is found
  # print all values
  print f[$1], $0
  }' file1 file2