Convert multi lines to single line with spaces and quotes

Question

How can I convert multi lines to a single line with spaces and quotes using awk or tr or any other tool which makes it simple (but not for loops)?

$ cat databases.txt
Wp_new
Frontend DB
DB_EXT

Expected:

$ cat databases.txt
"Wp_new" "Frontend DB" "DB_EXT"  

Edit 1:

Thanks for all the useful answers. But the one I marked as correct is the one which can be typed on terminal in short time and with fewer hassles (simplicity) so that I(syadmins) can do the operations very fast without making the systems downtime more.

Answer 1

It can be done with awk

awk '{printf("\"%s\" ",$0)} END { printf "\n" }' databases.txt

Output:

"Wp_new" "Frontend DB" "DB_EXT" 

Answer 2

With sed + paste

$ sed 's/.*/"&"/' databases.txt
"Wp_new"
"Frontend DB"
"DB_EXT"
$ sed 's/.*/"&"/' databases.txt | paste -sd' ' -
"Wp_new" "Frontend DB" "DB_EXT"

Or, just paste (courtesy https://unix.stackexchange.com/a/593240)

$ <databases.txt paste -d '"' /dev/null - /dev/null | paste -sd' ' -
"Wp_new" "Frontend DB" "DB_EXT"

---

If input has empty lines that should be ignored:

$ cat ip.txt
Wp_new
Frontend DB
DB_EXT
$ sed -n 's/..*/"&"/p' ip.txt | paste -sd' ' -
"Wp_new" "Frontend DB" "DB_EXT"

Answer 3

$ awk '{printf "%s\"%s\"", sep, $0; sep=OFS} END{print ""}' file
"Wp_new" "Frontend DB" "DB_EXT"

Answer 4

There are a number of ways of achieving the result using sed. Here are two solutions:

$ sed 's/^/"/;s/$/"/' infile | sed ':a;{N;s/\n/ /;ba}'
"Wp_new" "Frontend DB" "DB_EXT"

or

$ sed 's/.*/"&"/' infile | sed ':a;{N;s/\n/ /;ba}'
"Wp_new" "Frontend DB" "DB_EXT"

First, double quotes are added to the start and end of each text line, then the text lines are joined together.

Answer 5

GNU xargs

<databases.txt xargs -d'\n' printf '"%s"\n' | paste -sd\  ;

Or we can use perl also:

perl -l40 -012 -pe 's/^|$/"/g;$\=$/ if eof' databases.txt

Results:

"Wp_new" "Frontend DB" "DB_EXT"

Answer 6

It could be done in some sed with:

$ sed ':a;N;$!ba;s/\n/" "/g;s/.*/"&"/' databases.txt
"Wp_new" "Frontend DB" "" "DB_EXT" "" "empty"

Or, if you don't like branch and branch labels:

$ sed -n '/^$/!{                                          
    ${H;x;s/\n/" "/g;s/.*/"&"/;p;d;}
    $!{H;1h}
    }' databases.txt
"Wp_new" "Frontend DB" "DB_EXT" "empty"

But both load the whole file into memory, which could use a lot for long files.

With some help from paste, sed could read lines one-at-a-time:

$ sed 's/.*/"&"/' databases.txt | paste -sd ' '
"Wp_new" "Frontend DB" "" "DB_EXT" "" "empty"

There is no need for the usual '-' for paste as it reads from stdin by default when given no FILE.

It could also be done in awk with explicit values:

$ awk 'BEGIN{dq="\""; sp=""} {
     printf "%s%s%s%s", sp, dq, $0,dq; sp=" "
     }END{print ""}' databases.txt
"Wp_new" "Frontend DB" "DB_EXT"

Answer 7

Here’s another sed solution.  Inevitably, it has some overlap with the answers by fpmurphy and Sundeep.

{ sed 's/.*/"&"/; 1!s/^/ /' databases.txt | tr -d '\n'; echo;}

• Wrap each line in quotes.
• Add a space to the beginning of every line but the first.
• Delete all newlines.
• Add a newline at the end.

As Sundeep points out, you can move < databases.txt to the beginning of the command if you particularly prefer to see the input specification in that position (rather than in the middle of the command).  And you can replace the echo with printf '\n' — although, following up on Ed Morton’s comments, echo might do a better job of generating the appropriate end-of-line character(s) in something other than a pure Unix/Linux context (e.g., a Windows/GNU hybrid).

Answer 8

I love to use tr(1) to convert mult line strings into single line strings first and then work on them via sed(1) by first inserting the trailing and initial quote, then replacing all 'internal' semicolons, i.e.:

$ cat databases.txt | tr '\n' ';' | sed 's/;$/"\n/; s/^/"/; s/;/" "/g'
"Wp_new" "Frontend DB" "DB_EXT"

Of course you can choose any other character than ;, as long as it isn't contained in the the input itself.

While this should be easy to reason about, it is not necessarily portable and definitely not POSIX as correctly pointed out by @g-man-says-reinstate-monica. The issue lies in sed needing to read the whole line---here the entire file---while POSIX only requiring 8192 byte lines (1). Additionally, the input to sed must be a file (i.e. end with a newline 2).

I want to leave this trick here as it's still convenient if the above restrictions do not apply, however I want to stress it shouldn't be used as part of a script :)

Answer 9

Using Raku (formerly known as Perl_6)

raku -e 'lines>>.raku.put;' 

OR

raku -e 'lines.map(*.raku).put;' 

Sample Input:

Wp_new
Frontend DB
DB_EXT
This "quoted" ending comment

Sample Output:

"Wp_new" "Frontend DB" "DB_EXT" "This \"quoted\" ending comment"

If you play with the various commands above, you'll find that the lines command reads input lazily (stripping newlines by default), the raku (or perl) command gives you an internal 'Perlish/Rakuish' representation of the input (i.e. adds quotes), and the put command means 'print-using-terminator'.

If the above code is unmemorizable and/or too long to type, you could try 'meeting-Raku-halfway' with the following code (i.e. below returns more "Rakuish" output):

raku -e 'lines.list.raku.put;'  databases.txt  #OP's database.txt file
("Wp_new", "Frontend DB", "DB_EXT")

Or more simply:

raku -e 'lines.raku.put;'  databases.txt  #OP's database.txt file
("Wp_new", "Frontend DB", "DB_EXT").Seq

https://docs.raku.org/routine/lines
https://raku.org/

Answer 10

All answer are nice, I guess this depend about what output did you expect. If you want a raw line text with no additional characters or if is necessary to add some, I tried this and it works very nice to me:

Simply collapse the text:

cat yourFile | paste -sd' ' -
>item1 item2 item3

Surround item with double-quotes:

sed -n 's/..*/"&",/p' yourFile | paste -sd' ' -
>"item1", "item2", "item2",

Answer 11

awk 'ORS=" "{print "\""$0"\""}' filename

output

"Wp_new" "Frontend DB" "DB_EXT"