Concise and portable "join" on the Unix command-line

Solution 1:

Perhaps a little surprisingly, paste is a good way to do this:

paste -s -d","

This won't deal with the empty lines you mentioned. For that, pipe your text through grep, first:

grep -v '^$' | paste -s -d"," -

This sed one-line should work -

sed -e :a -e 'N;s/\n/,/;ba' file

Test:

[jaypal:~/Temp] cat file
foo
bar
baz

[jaypal:~/Temp] sed -e :a -e 'N;s/\n/,/;ba' file
foo,bar,baz

To handle empty lines, you can remove the empty lines and pipe it to the above one-liner.

sed -e '/^$/d' file | sed -e :a -e 'N;s/\n/,/;ba'

How about to use xargs?

for your case

$ cat foo.txt | sed 's/$/, /' | xargs

Be careful about the limit length of input of xargs command. (This means very long input file cannot be handled by this.)

Perl:

cat data.txt | perl -pe 'if(!eof){chomp;$_.=","}'

or yet shorter and faster, surprisingly:

cat data.txt | perl -pe 'if(!eof){s/\n/,/}'

or, if you want:

cat data.txt | perl -pe 's/\n/,/ unless eof'