Shell Programming and Scripting

1,2,3
3,4,5,6,7,8
10,11,23,24

1,2,3,?,?,?
3,4,5,6,7,8
10,11,23,24,?,?

awk -F, 'END {
  for (i = 0; ++i <= NR;) {
    n = split(r[i], t)
    for (j = 0; ++j <= m;)
      printf "%s", (t[j] ? t[j] : "?") (j < m ? OFS : RS)
    }
  }
{
  r[NR] = $0; NF > m && m = NF
  }' OFS=, infile

perl -F, -lane'
  push @r, [@F]; @F > $m and $m = @F;
  END {
    for $l (@r) {
	print join ",", 
	  map $$l[$_] || "?", 0 .. $m - 1
    } 
  }' infile

awk -F, 'NR==FNR{ nf=nf<NF?NF:nf; next } {
  for(i=NF+1;i<=nf;i++){$0=$0 ",?"}
}
1' file file

{ IFS="," ; while read a b c d e f ; do echo "${a:=?},${b:=?},${c:=?},${d:=?},${e:=?},${f:=?}" ; done }<input

# cat infile
1,2,3
3,4,5,6,7,8
10,11,23,24

# { IFS="," ; while read a b c d e f ; do echo "${a:=?},${b:=?},${c:=?},${d:=?},${e:=?},${f:=?}" ; done }<infile
1,2,3,?,?,?
3,4,5,6,7,8
10,11,23,24,?,?
?,?,?,?,?,?
#