Sorting and removing duplicate words in a line

Question

The sort command lets me put lines in alphabetical order and remove duplicate lines. I need something similar that can sort the words on a single line, put them

Answer 1

Using perl:

perl -lane '
  %a = map { $_ => 1 } @F;
  print join qq[ ], sort keys %a;
' <<< "zebra ant spider spider ant zebra ant"

Result:

ant spider zebra

Answer 2

Use tr to change spaces to new lines, then sort, and finally change new lines back to spaces.

echo $(tr ' ' '\n' <<< "zebra ant spider spider ant zebra ant" | sort -u)

Answer 3

The shell was built to parse [:blank:] seperated word lists already. Therefore the use of xargs is completely redundant. The "unique" stuff can be done but its just easier to use sort.

echo $(printf '%s\n' zebra ant spider spider ant zebra ant | sort -u)

Answer 4

Use python

$ echo "zebra ant spider spider ant zebra ant" | python -c 'import sys; print(" ".join(sorted(set(sys.stdin.read().split()))))'
ant spider zebra

Answer 5

Using awk:

awk '{for(i=1;i<=NF;i++) a[$i]++} END{for(i in a) printf i" ";print ""}' INPUT_FILE

Test:

[jaypal:~/Temp] cat file
zebra ant spider spider ant zebra ant
[jaypal:~/Temp] awk '{for (i=1;i<=NF;i++) a[$i]++} END{for (i in a) printf i" ";print ""}' file
zebra spider ant 

Answer 6

This works for me:

$ echo "zebra ant spider spider ant zebra ant" | xargs -n1 | sort -u | xargs
ant spider zebra

You can transform a list of words in a single row to a single column with xargs -n1 , use sort -u and transform back to a single row with xargs.