1列に複数の文字列を処理する方法

努力する：

awk '{print $1, $2}' OFS=, infile
aa.com,1.21.3.4,string1,string2
bb.com,5.6.7.8,string1,string2

この場合、最初または2番目のフィールドにスペースがある場合は、次のようにします。

awk -F, '{ match($3, /[^ ]* +[^ ]*/); 
           bkup=substr($3, RSTART, RLENGTH);
           gsub(/ +/, ",", bkup); # replace spaces with comma
           print $1, $2, bkup
}' OFS=, infile

説明する：読む男性awk:

match(s, r [, a])  
          Return the position in s where the regular expression r occurs, 
          or 0 if r is not present, and set the values of RSTART and RLENGTH. (...)

substr(s, i [, n])
          Return the at most n-character substring of s starting at I.
          If n is omitted, use the rest of s.

RSTART
          The index of the first character matched by match(); 0 if no
          match.  (This implies that character indices start at one.)

RLENGTH
          The length of the string matched by match(); -1 if no match.