awk-Printing column value without new line and adding comma

Question

input.txt

 EN1
 EN2
 EN3
 EN4
 EN5

output

EN1,EN2,EN3,EN4,EN5

I have tried awk.But it is not printing with comma

awk 'BEGIN { OFS = ","} { printf $1}' input.txt

I have GNU Awk 4.0.0 version

Answer 1

awk 'BEGIN{ORS=","}1' input.txt

yields this:

EN1,EN2,EN3,EN4,EN5,

so is printing with a comma (so I'm not sure I understand your comment in your post about this not happening) though I suspect the trailing comma is a problem.

Tested with GNU Awk 3.1.7

Answer 2

I know, old topic, but I could not resist - here's yet another short and simple way to do this:

$ paste -sd, input.txt
EN1,EN2,EN3,EN4,EN5
$

Works on Linux and Solaris, maybe even on other platforms.

Answer 3

You can use tr in such situation.

tr '\n' ',' <input.txt

This replaces the final newline by a comma as well. To avoid this, on Linux, if you know that the input file does end with a newline:

<input.txt head -c -1 | tr '\n' ,

Add ; echo if you want the output to be terminated by a newline.

Alternatively, you can get the shell to remove a trailing comma if there is one.

columns=$(<input.txt tr '\n' ',')
echo "${columns%,}"

Answer 4

There's also xargs and sed:

$ xargs <input.txt | sed -e 's/ /,/g'
EN1,EN2,EN3,EN4,EN5

An advantage here is that there is no trailing comma to get rid of.

xargs to combine the input lines, sed to replace all spaces with commas. I use this routinely to construct regular expressions (replace spaces with |) and quick sums to pipe into bc (replace spaces with +).

(FYI xargs defaults to echo as the command if none is provided)

NOTE: This only works if the input file is as described (one field per line, no spaces). If there are more fields and/or spaces in the input you can use awk or sed to pre-process the input. For example, with input like this:

EN1 foo bar
EN2 bar foo
EN3 baz quux
EN4 abc def
EN5 hij klm

Here awk is used to extract only the first field:

$ awk '{print $1}' input.txt | xargs | sed -e 's/ /,/g'
EN1,EN2,EN3,EN4,EN5

In this second (sed) example, spaces in the original input are replaced with some other string (chosen as unlikely to be in the original input), then fed into xargs. sed then replaces the spaces added by xargs, and then restores the strings from the input:

$ sed -e 's/ /--space--/g' input.txt | xargs | sed -e 's/ /,/g' -e 's/--space--/ /g'
EN1 foo bar,EN2 bar foo,EN3 baz quux,EN4 abc def,EN5 hij klm

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Now for some gratuitous op-ed commentary:

One of the most useful pieces of knowledge about unix text processing tools is that you can and should should think of data as being almost infinitely malleable - you can transform it into whatever form you need either to provide input to another process or to produce the output you want or both.

This is part of the reason why unix people tend to hate proprietary data formats - it's not just a philosophical disapproval or a wish to avoid vendor lock-in, it's also the very pragmatic fact that they make it difficult for us to manipulate and use our data in ways that weren't foreseen by the software's developers.

Answer 5

A solution that doesn't print a comma at the end of the line:

{printf("%s", NR == 1 ? $0 : ","$0);} END {printf("\n");} file

Explanation

When the first line is seen (NR == 1), only it is printed; otherwise a comma and the line are sent as arguments to printf.

This solution uses AWK's ternary operator ?:, that is:

NR == 1 ? $0 : ","$0

If the NR variable is equal to 1, then it sends the first line as the argument to printf; else it sends a comma concatenated with the current line.

Answer 6

perl -pe '(eof)?s/\s+$//:s/\s+$/,/' input.txt  

output: no trailing \n

EN1,EN2,EN3,EN4,EN5

Answer 7

sed -z 's/\n/,/g' input.txt

The -z option (only in sed version 4.2 or later) expects zero-byte as the end of record character instead of the newline character, treating this whole input file as a single line. Search for \n (newline character) and replace with comma. The g makes the search-replace global.

It converts the final newline character to a comma too, but it's easy to convert the final comma back:

sed -z 's/\n/,/g' input.txt | sed 's/,$/\n/'

The $ symbol marks the end of the line, so it replaces the final comma with a newline character.

Note that if your input file does contain any zero-bytes (often used in binary files to terminate strings) then this will see them as end of record markers. The example above shouldn't be affected, but in some situations it can give unexpected results.