I have a file that I need to reformat so that every time I match a certain string in the first column it prints to the string as the heading and under the sting it prints the remaining entries on the line that matched the string.

For example, I need to reformat this

xxx : yyy zzz
11 : 111 222 xxx
xyz : abc def
xxx : aaa bbb
11 : 555 333 yy
xyz : abc xyz

xxx              11                   xyz
yyy zzz        111 222 xxx      abc def
aaa bbb        555 333 yy      abc xyz

awk -F: ' BEGIN {
 printf "%-15s%-15s%-15s\n", "xxx", "11", "xyz" } {
 if(NR%3==0) {
  sub(" ","",$2);
  printf "%-15s\n", $2;
 }
 else {
  sub(" ","",$2);
  printf "%-15s", $2;
 }
} ' infile

If you were looking for something that self adjusts based on the column headings and data to be displayed, you could try something like:

awk -F" : " '
# c[heading] = # of values accumulted for heading
# h[heading] = heading_field
# hc = # of headings
# ho[heading_field] = heading
# r = # of rows to be printed (not counting headings)
# v[heading,c[heading]] = value to be printed in row c[heading] under heading
# w[heading_field] = widest field data for heading_field
{       v[$1,++c[$1]] = $2
        if(!($1 in h)) {
                ho[++hc] = $1
                h[$1] = hc
                w[hc] = length($1)
        }
        if(w[h[$1]] < length($2)) w[h[$1]] = length($2)
        if(c[$1] > r) r = c[$1]$1, c[$1], $1, h[$1], hc, ho[hc], r, $1, $1, c[$1], v[$1,c[$1]], h[$1], w[h[$1]])}
END {   for(i = 1; i < hc; i++)
                printf("%-*.*s", w[i] + 3, w[i] + 3, ho[i])
        printf("%-s\n", ho[hc]);
        for(j = 1; j <= r; j++) {
                for(i = 1; i < hc; i++)
                        printf("%-*.*s", w[i] + 3, w[i] + 3, v[ho[i], j]);
                printf("%-s\n", v[ho[hc], j]);
        }
}' file

xxx       11            xyz
yyy zzz   111 222 xxx   abc def
aaa bbb   555 333 yy    abc xyz

try also:

awk -F" *: *" '!a[$1]++ {b[c++]=$1;}
{cn=ca[$1]++; e[$1]=$1; d[$1, a[$1]-1]=$2;}
END {
  for (i=0; i<c; i++) {printf("%-20s", b[i])}; print "";
  for (j=0; j<=cn; j++) {for (i=0; i<c; i++) {printf("%-20s",d[e[b[i]],j])} print ""; }
}' infile

Thank you very much guys. These posts have been extremely helpful. They all work!