How to replace second pattern(dot) after pattern(comma) in bash - regex

Question

How do i replace second dot after comma.
this is the closest i could go
echo '0.592922148,0.821504176,1.174.129.731' | xargs -d ',' -n1 echo | sed 's/\([^\.]*\.[^\.]*\)\./\1/' | sed 's/\([^\.]*\.[^\.]*\)\./\1/'
Output :
0.592922148
0.821504176
1.174129731
Expected output :
0.592922148,0.821504176,1.174129731

Answer 1

You may use
sed -e ':a' -e 's/\(\.[^.,]*\)\./\1/' -e 't a'
See online sed demo:
s='0.592922148,0.821504176,1.174.129.731'
sed -e ':a' -e 's/\(\.[^.,]*\)\./\1/' -e 't a' <<< "$s"
Details
:a - label a
s/\(\.[^.,]*\)\./\1/ - finds and captures into Group 1 a dot, then any 0+ chars other than dot and comma, and then just matches a dot, and replaces this match with the value in Group 1 (thus, removing the second matched dot)
t a - if there was a successful replacement, goes back to the a label position in the string.

Answer 2

While I think the sed solution is your best choice, since you have tagged your question with both sed and awk, an awk solution is fairly straight forward as well using split() and basic string concatenation. (just not nearly as short) For example you could do:
awk -v OFS=, -F, '{
for (i=1; i<=NF; i++) {
n=split ($i, a,".")
if (n > 2) {
s=a[1] "." a[2]
for (j=3; j<=n; j++)
s = s a[j]
$i=s
}
}
}1'
Where you define the field separator and output field separators as ','. Then looping over each field, check the return of split(), splitting the field into an array on '.' into array a. If the resulting number of elements is greater than 2, then put your first two elements back together restoring the first '.' in the number, and then simply concatenate the remaining fields. The 1 at the end is the default "print record" to print the updated record.
Example Use/Output
$ echo '0.592922148,0.821504176,1.174.129.731' |
> awk -v OFS=, -F, '{
> for (i=1; i<=NF; i++) {
> n=split ($i, a,".")
> if (n > 2) {
> s=a[1] "." a[2]
> for(j=3;j<=n;j++)
> s = s a[j]
> $i=s
> }
> }
> }1'
0.592922148,0.821504176,1.174129731

Answer 3

Could you please try following.
echo '0.592922148,0.821504176,1.174.129.731' |
awk '
BEGIN{
FS=OFS=","
}
{
for(i=1;i<=NF;i++){
ind=index($i,".")
if(ind){
val1=substr($i,1,ind)
val2=substr($i,ind+1)
gsub(/\./,"",val2)
$i=val1 val2
}
}
val1=val2=""
}
1'
Explanation: Adding explanation for above code.
echo '0.592922148,0.821504176,1.174.129.731' | ##Printing values as per OP mentioned and using pipe to send its output as standard input for awk command.
awk ' ##Starting awk program from here.
BEGIN{ ##Starting BEGIN section of this program here.
FS=OFS="," ##Setting FS and OFS as comma for each line of Input_file here.
} ##Closing BEGIN BLOCK here.
{
for(i=1;i<=NF;i++){ ##Starting a for loop to traverse through fields of line..
ind=index($i,".") ##Checking index of DOT in current field and saving it into ind variable.
if(ind){ ##Checking condition if variable ind is NOT NULL.
val1=substr($i,1,ind) ##Creating variable val1 from sub-string in current field from 1 to ind value.
val2=substr($i,ind+1) ##Creating variable val2 from sub-string in current field from ind+1 value to till complete length of current field.
gsub(/\./,"",val2) ##Globally substituting DOTs with NULL in val2 variable.
$i=val1 val2 ##Re-crearing current field with value of val1 val2.
} ##Closing BLOCK for if condition.
} ##Closing BLOCK for for loop.
val1=val2="" ##Nullifying val1 and val2 variables here.
} ##Closing main code BLOCK here.
1' ##Mentioning 1 will print edited/non-edited line.

Answer 4

An awk verison:
echo '0.592922148,0.821504176,1.174.129.731' | awk -F, '{for (i=1;i<=NF;i++) {sub(/\./,"#",$i);gsub(/\./,"",$i);sub(/#/,".",$i);print $i}}'
0.592922148
0.821504176
1.174129731
It splits the line inn to multiple fields by ,. Then replace first . to #. Then replace rest of . to nothing. Last replace # back to . and print it.
Edit
awk -F, '{for (i=1;i<=NF;i++) {sub(/\./,"#",$i);gsub(/\./,"",$i);sub(/#/,".",$i);a=a (i==1?"":",")$i}print a}' file
0.592922148,0.821504176,1.174129731