Turning multiple lines into one comma separated line

Question

I have the following data in multiple lines:

foo
bar
qux
zuu
sdf
sdfasdf

What I want to do is to convert them to one comma separated line:

foo,bar,qux,zuu,sdf,sdfasdf

What's the best unix one-liner to do that?

Solution 1

Using paste command:

paste -d, -s file

Solution 2

file

aaa
bbb
ccc
ddd

xargs

cat file | xargs

result

aaa bbb ccc ddd 

xargs improoved

cat file | xargs | sed -e 's/ /,/g'

result

aaa,bbb,ccc,ddd 

Solution 3

There are many ways it can be achieved. The tool you use mostly depends on your own preference or experience.

Using tr command:

tr '\n' ',' < somefile

Using awk:

awk -F'\n' '{if(NR == 1) {printf $0} else {printf ","$0}}' somefile

Solution 4

xargs -a your_file | sed 's/ /,/g'

This is a shorter way.

Solution 5

based on your input example, this awk line works. (without trailing comma)

awk -vRS="" -vOFS=',' '$1=$1' file

test:

kent$  echo "foo
bar
qux
zuu
sdf
sdfasdf"|awk -vRS="" -vOFS=',' '$1=$1' 
foo,bar,qux,zuu,sdf,sdfasdf

View more solutions

Comments

[Kent]

your both commands would generate ending comma

[n3rV3]

yes, i can fix it in awk but not in tr, give me a min.

[sid_com]

Even more cryptic: perl '-peeof||s|$/$|,|' file

[Chris Seymour]

You only need to use -v if you want the variables available in the BEGIN block, slightly more concise awk '$1=$1' RS= OFS=, file.

[Chris Seymour]

awk '{printf NR==1?$0:","$0}' file

[n3rV3]

cool, thanks for that

[Ed Morton]

Never use printf $0 as it will fail cryptically if $0 contains any printf formatting characters. The synopsis for printf is printf format, data so use printf "%s", $0 instead.

[Ed Morton]

For clarity and to avoid getting surprised when you later do try to use a variable in a BEGIN block, I'd always use -v unless setting a variable to different values between files. FYI omitting the space between -v and the variable name makes your script un-necessarily gawk-specific so I'd use -v RS= instead of -vRS=.

[Kent]

@EdMorton thx for the comment. (the "space" between -v and va). I learned many tips from you :). Personally I always use -v too.

[n3rV3]

i still have a lot to learn. thanks

[protist]

sid_com, I like your choice of substitution delimiters :D... perl -pe 'eof or s#\n$#,#' thing

[Serhii Kuzmychov]

xargs turns multi-line into one line space-separated, then sed replaces all space by ','(or ' ,' if you will use sed -e 's/ /\ ,/g' ( by the way -e can be omited)

[Serhii Kuzmychov]

usually xargs is not intended for t but it works :)

[Serhii Kuzmychov]

and it more prefer way for every day use insted of the one bellow

[Ray Hunter]

paste is an awesome command. Works like a champ!

[Peter K]

ok, even more cryptic perl: perl -l54 -pe 'eof and $\=""' file (and you can go with empty script body if you can tolerate last coma)

[NeoMorfeo]

But how to accomplish that for a variable or a pipe? Update myself: Using -s without value .... | paste -d, -s

[CoderGuy123]

While this works for when one wants to convert newlines (\n) into commas, it seems that one cannot use this method if one needs to convert newlines into ", " which is required for many other commands.

[cadrian]

except if there are spaces in your lines...

[Serhii Kuzmychov]

sed -e 's/ /+/g' test |xargs|sed 's/ /,/g;s/+/ /g' it was just an idea how to use xargs :) do not think it is seriously

[Bee Kay]

Thanks for the step by step! I had a file with one entry per line, (fn, ln,id,status, blank line.) I needed it in CSV, so I swapped "blank line" with an unused symbol (sed -e 's/^$/#/') before using the mod you've explained.

[Carson Anderson]

@NeoMorfeo You can use a - to read from pipe as well. Ex: echo -e "1\n2\n3" | paste -d, -s -

[Lazarus Thurston]

too complicated. Please explain @protist.

[jimh]

I found this to be the solution I was looking for, not the accepted one because it works for pipes and multiple files and you can pass it to tr -s " " "\t" if you want to add tabs and so forth. Thank you.