Looping over input fields as array

Question

Is it possible to do something like this:

$ cat foo.txt
1 2 3 4
foo bar baz
hello world
$ awk \'{ for(i in $){ print $[i]; } }\' foo.txt
1
2
3
4
foo
bar
baz
         


        

Answer 1

Found out myself:

$ awk '{ for(i = 1; i <= NF; i++) { print $i; } }' foo.txt

Answer 2

I'd use sed:

sed 's/\ /\n/g' foo.txt

Answer 3

No need for awk, sed or perl. You can easily do this directly in the shell:

for i in $(cat foo.txt); do echo "$i"; done

Answer 4

If you're open to using Perl, either of these should do the trick:

perl -lane 'print $_ for @F' foo.txt
perl -lane 'print join "\n",@F' foo.txt

These command-line options are used:

• -n loop around each line of the input file, do not automatically print the line
• -l removes newlines before processing, and adds them back in afterwards
• -a autosplit mode – split input lines into the @F array. Defaults to splitting on whitespace.
• -e execute the perl code