UNIX for Dummies Questions & Answers

awk 'NR > 4{print $2, $3}' OFS="," file > file.csv

        E/N       Ko_exp   %err  Ko_calc  %err   diff  diff-  diff+  0.95
        ========  =======  ====  =======  ====  =====  =====  =====  ====
     1      4.00   2.8100   3.0   3.9502   0.5  -1.14  -1.31  -0.97    0
     2      8.00   2.8123   3.0   3.9668   0.5  -1.15  -1.32  -0.98    0
     3     12.00   2.8300   3.0   3.9920   0.5  -1.16  -1.33  -0.99    0
     4     16.00   2.8444   3.0   4.0201   0.5  -1.18  -1.35  -1.00    0
     5     20.00   2.8700   3.0   4.0473   0.5  -1.18  -1.35  -1.00    0
     6     24.00   2.9007   3.0   4.0668   0.5  -1.17  -1.34  -0.99    0
     7     28.00   2.9437   3.0   4.0807   0.5  -1.14  -1.31  -0.96    0
     8     32.00   2.9983   3.0   4.0833   0.5  -1.08  -1.27  -0.90    0
     9     36.00   3.0567   3.0   4.0778   0.5  -1.02  -1.21  -0.84    0
    10     40.00   3.1100   3.0   4.0656   0.5  -0.96  -1.14  -0.77    0
    11     44.00   3.1518   3.0   4.0452   0.5  -0.89  -1.08  -0.70    0
    12     48.00   3.1849   3.0   4.0209   0.5  -0.84  -1.03  -0.64    0
    13     52.00   3.2148   3.0   3.9924   0.5  -0.78  -0.97  -0.58    0
    14     56.00   3.2434   3.0   3.9619   0.5  -0.72  -0.91  -0.52    0
    15     60.00   3.2700   3.0   3.9269   0.5  -0.66  -0.85  -0.46    0
    16     64.00   3.2936   3.0   3.8904   0.5  -0.60  -0.79  -0.40    0
    17     68.00   3.3137   3.0   3.8491   0.5  -0.54  -0.73  -0.34    0
    18     72.00   3.3300   3.0   3.8136   0.5  -0.48  -0.68  -0.28    0
    19     76.00   3.3422   3.0   3.7762   0.5  -0.43  -0.63  -0.23    0
    20     80.00   3.3500   3.0   3.7357   0.5  -0.39  -0.59  -0.19    0
    21     84.00   3.3531   3.0   3.7083   0.5  -0.36  -0.56  -0.15    0
    22     88.00   3.3521   3.0   3.6682   0.5  -0.32  -0.52  -0.12    0

# to extract the "default" columns: 'E/N' and 'Ko_exp'
nawk -f gin.awk gin.txt

# to extract the specific columns: '%err' and 'diff-'
nawk -v colID='%err diff-' -f gin.awk gin.txt

BEGIN {
  if (colID=="") colID="E/N Ko_exp";

  colNn=split(colID, colN, FS)
  for(i=1; i<=colNn; i++) {
     colN[colN[i]]
     delete colN[i]
  }

  FLDheader="1"
  FLDskip="2"
}

FNR == FLDheader {
   for(i=1; i <= NF; i++) {
      if ($i in colN) {
         colA[++col]=i
         printf("%s%c", $i, (i!=NF)?OFS:"")
      }
   }
   if (col != colNn) {
     printf("Warning: couldn't find column(s) [%s]\n", colID) | "cat 1>&2"
     exit 1;
   }
   printf("%c", ORS)
   next;
}

NR != FLDskip {
   for(i=1; i<=col; i++)
      printf("%s%c", $(colA[i]+1), (i==col)? ORS : OFS)
}

awk 'NR > 4 && NR < 101 {print $2, $3}' OFS="," file > file.csv