gsub issue with awk (gawk)

Question

I need to search a text file for a string, and make a replacement that includes a number that increments with each match.

The string to be "found" could be a single character, or a word, or a phrase.

The replacement expression will not always be the same (as it is in my examples below), but will always include a number (variable) that increments.

For example:

1) I have a test file named "data.txt". The file contains:

Now is the time
for all good men
to come to the
aid of their party.

2) I placed the awk script in a file named "cmd.awk". The file contains:

/f/ {sub ("f","f(" ++j ")")}1

3) I use awk like this:

awk -f cmd.awk data.txt

In this case, the output is as expected:

Now is the time
f(1)or all good men
to come to the
aid of(2) their party.

The problem comes when there is more than one match on a line. For example, if I was searching for the letter "i" like:

/i/ {sub ("i","i(" ++j ")")}1

The output is:

Now i(1)s the time
for all good men
to come to the
ai(2)d of their party.

which is wrong because it doesn't include the "i" in "time" or "their".

So, I tried "gsub" instead of "sub" like:

/i/ {gsub ("i","i(" ++j ")")}1

The output is:

Now i(1)s the ti(1)me
for all good men
to come to the
ai(2)d of thei(2)r party.

Now it makes the replacement for all occurrences of the letter "i", but the inserted number is the same for all matches on the same line.

The desired output should be:

Now i(1)s the ti(2)me
for all good men
to come to the
ai(3)d of thei(4)r party.

Note: The number won't always begin with "1" so I might use awk like this:

awk -f cmd.awk -v j=26 data.txt

To get the output:

Now i(27)s the ti(28)me
for all good men
to come to the
ai(29)d of thei(30)r party.

And just to be clear, the number in the replacement will not always be inside parenthesis. And the replacement will not always include the matched string (actually it would be quite rare).

The other problem I am having with this is...

I want to use an awk-variable (not environment variable) for the "search string", so I can specify it on the awk command line.

For example:

1) I placed the awk script in a file named "cmd.awk". The file contains something like:

/??a??/ {gsub (a,a "(" ++j ")")}1

2) I would use awk like this:

awk -f cmd.awk -v a=i data.txt

To get the output:

Now i(1)s the ti(2)me
for all good men
to come to the
ai(3)d of thei(4)r party.

The question here, is how do I represent the the variable "a" in the /search/ expression ?

Answer 1

awk version:

awk '{for(i=2; i<=NF; i++)$i="(" ++k ")" $i}1' FS=i OFS=i