Extract part of string from each column' rows

Using awk with only POSIX defined constructs,

awk 'match($4, /Gene:(.+)\:/){ $4=substr($4, RSTART, RLENGTH-1) }1' file

To make the output a bit more neatly aligned, pipe the output to | column -t which will tab separate your columns. If you are unsure of the position of Gene:genename in your line, change the awk to look for the pattern anywhere within the line and modify the 4th column with the required value. Changing to $4 to $0 (the whole line) should work just fine.

awk 'match($0, /Gene:(.+)\:/){ $4=substr($0, RSTART, RLENGTH-1) }1' file

perl -pale 's#(?:\H+\h+){3}\K\H+#($F[3] =~ /(?:^|;)(Gene:[^:]+)/)[0]#e' input-file.txt 

° in the case of no fixed location of gene in the fourth field, we can do as above.

° we zero in on the fourth field by means of regex (?:\H+\h+){3}\K\H+ and promptly replace that with another regex used in the substitute portion of the s///e command.

Treating column four as a list of strings delimited by either ; or : and replacing the whole column with the string Gene and the following one (the gene name) by first splitting that field and then finding the bit we want:

$ awk -vOFS='\t' '{ split($4,a,"[;:]"); for (i in a) if (a[i]=="Gene") { $4 = a[i] ":" a[i+1]; break } } 1' file
7       128550681       128550681       Gene:KCP        1       1       0       0
1       17718672        17718672        Gene:PADI6      1       1       0       0
1       17718672        17718672        Gene:PADI6      1       1       0       0
4       86035   86035   Gene:ZNF595     1       1       0       0
3       12942851        12942851        Gene:IQSEC1     1       1       0       0

Perl:

perl -F'\h+' -lane '
    for ( $F[3] ) {
        my $a = index(";$_", ";Gene:"     );
        my $b = index(";$_", ":",    $a+6 );
        $_ = substr(";$_", $a+1, $b-$a-1);
    }
    print join "\t", @F;
' input-file.txt

Output:

7   128550681   128550681   Gene:KCP    1   1   0   0
1   17718672    17718672    Gene:PADI6  1   1   0   0
1   17718672    17718672    Gene:PADI6  1   1   0   0
4   86035   86035   Gene:ZNF595 1   1   0   0
3   12942851    12942851    Gene:IQSEC1 1   1   0   0
$   128550681   128550681   Gene:$$$    1   1   0   0

Explanation:

• perl options:
  • -n => invoke a line-by-line read of the input.
  • -F => will make FS = horizontal whitespace.
  • -a => split each line into fields (based on whatever FS was set by -F option or a single space by default) and store them in the array @F.
  • -l => will make RS = ORS = "\n".
  • -e => what follows is to be treated as Perl code and applied on each line, a.ka., record.
• data structures involved:
  • @F => the array populated with the fields got by splitting the record. Indexed from 0. So $F[3] is the fourth field in the record.
  • $a => holds the position of the substring ;Gene: in the 4th field.
  • $b => holds the position of the substring : in the 4th field, that is found looking 6 digits AFTER the position of ;Gene:. IOW, it finds the second : after the ;Gene. Note: We pad a semicolon to the search string, that is, $F[3], since the position of Gene: can be anywhere, so it can very well be at the beginning of he fourth field as well. This is to take care of that eventuality.
  • $_ => holds the localized version of $F[3] inside a for loop. the substr builtin will extract the gene:... info and store it back in $F[3].
  • Note: the my qualifier before the variable definitions for $a,$b mark them to be lexical variables whose scope is limited to the for loop only.
  • Note: $_ inside the for loop does NOT refer to the current record/line. It has been overloaded and localized for the duration of the for loop to be $F[3].

GNU Sed:

sed -Ee '
    s/\S+/\n&\n/4
    s/\n(.*;)?(Gene:[^:]+):.*\n/\2/
' input-file.txt

Explanation:

• We mark out the fourth field with newlines.
• Having staked out the region in the current line, we then fish out the required data, in our case, Gene: and after that, as many non colons we meet on the way before we hit the next colon.
• This method does not disturb the spacing existing between the various fields. This may or may not be important.
• Note FYI: Assumes a single gene in the fourth field. For multiple genes, it won't error out or warn, rather silently pick the last gene of the 4th field of that record.