26

I have simple text file named "example".

Reading with terminal command: cat example

Output:

abc cdef ghi jk lmnopq rst uv wxyz

I want to convert (transform) into following form: (expected output from cat example)

abc
cdef
ghi
jk
lmnopq
rst
uv
wxyz

How can I do this via the command-line?

(This is only an example file, I want to convert word's position in vertical-column)

1
54

A few choices:

  1. The classic, use tr:

    tr ' ' '\n' < example
    
  2. Use cut

    cut -d ' ' --output-delimiter=$'\n' -f 1- example
    
  3. Use sed

    sed 's/ /\n/g' example
    
  4. Use perl

    perl -pe 's/ /\n/g' example
    
  5. Use the shell

    foo=$(cat example); echo -e ${foo// /\\n}
    
3
  • 1
    For the sed example I needed to add a $ to get bash to replace with an actual newline ie: sed $'s/ /\\\n/g' example
    – acumartini
    Sep 9 '19 at 20:38
  • 1
    Above example for OSX sed, for gnu-sed: sed $'s/ /\\n/g'
    – acumartini
    Sep 9 '19 at 20:44
  • 1
    @acumartini GNU sed (which is the default on Ubuntu, the others aren't relevant on this site) can deal with \n without requiring ANSI-C quotes. So on a GNU system, sed 's/ /\n/g' example works fine and there is no need for sed $'s/ /\\n/g'. You needed to add the $ because macOS uses BSD sed, but that isn't on topic here.
    – terdon
    Feb 24 '21 at 10:51
16

Try the below command

awk -v RS=" " '{print}' file

OR

awk -v RS='[\n ]' '{print}' file

Example:

$ awk -v RS=" " '{print}' example
abc
cdef
ghi
jk
lmnopq
rst
uv
wxyz

Explanation:

RS (Record separator) is an built-in awk variable. In the first command, the value given to the Record separator variable is space. Awk breaks the line from printing whenever it finds a space.

In the second command, the value given to the RS variable is space or a new line character.This command eliminates the extra blank line appeared while running the first command.

0
10

You can use xargs,

cat example | xargs -n 1

or, better

xargs -n 1 < example
1
  • 7
    xargs -n 1 < example saves you 1 kitten
    – Rinzwind
    May 5 '14 at 14:48
3

Using a perl oneliner:

perl -p -i -e 's/\s/\n/g' example

It will replace spaces and tabs with "ENTER" (aka \n)

1
  • How can I do visa versa replacing new-line with spaces?
    – alper
    Jan 17 at 18:18
2

No one posted python, so here's that:

python -c "import sys;lines=['\n'.join(l.strip().split()) for l in sys.stdin.readlines()];print('\n'.join(lines))" < input.txt 

We redirect input file into python's stdin stream, and read it line by line. Each line is stripped of its trailing newline, split into words, and then rejoined into one string where each word is separated by newline.This is done to ensure having one word per line and avoid multiple newlines being inserted in case there's multiple spaces next to each other. Eventually we end up with list of strings, which is then again joined into larger string, and printed out to stdout stream. That later can be redirected to another file with > out.txt redirection.

1

Similar to the 'tr' above but with the additions:

  • Also works for tabs

  • Converts multiple spaces or tabs to 1 newline

    tr -s '[:space:]' '\n' < example
    
1
  • This was the fastest for me, processing millions of lines.
    – osolmaz
    Sep 19 '21 at 19:21

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