Convert text file into a comma delimited string

Question

I don\'t seem to locate an SO question that matches this exact problem.

I have a text file that has one text token per line, without any commas, tabs, or quotes. I want

Answer 1

With Perl one-liner:

$ cat csv_2_text
one
two
three
$ perl -ne '{ chomp; push(@lines,$_) } END { $x=join(",",@lines);  print "$x" }' csv_2_text
one,two,three

$ perl -ne ' { chomp; $_="$_," if not eof ;printf("%s",$_) } ' csv_2_text
one,two,three
$

From @codeforester

$ perl -ne 'BEGIN { my $delim = "" } { chomp; printf("%s%s", $delim, $_); $delim="," } END { printf("\n") }' csv_2_text
one,two,three
$