Sorting and removing duplicate words in a line

Question

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.

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)

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)

All of the answers prior to this one can only sort a single line at time. The following can be used to pipe a whole list of such lines into and it will print the sorted list of unique words for each line.

awk '{ delete a; for (i=1; i<=NF; i++) a[$i]++; n=asorti(a, b); for (i=1; i<=n; i++) printf b[i]" "; print "" }'

Thanks @jaypai for a lot of the syntax used in this.

Example:

>cat file
group label wearable edit_group edit_group_order label_max camera_elevation camera_distance name label_min label_max value_min value_max camera_angle camera_elevation id
id group label wearable edit_group clothing_morph value_min value_max name value_default clothing_morph group
id label show_simple wearable name edit_group edit_group_order group clothing_morph clothing_morph camera_distance label_min label_max value_min value_max camera_distance camera_angle
id group label wearable name edit_group clothing_morph value_min value_max value_default
group label wearable id clothing_morph edit_group edit_group_order label_min label_max value_min value_max name camera_distance camera_angle camera_elevation
id group label wearable edit_group name label_min label_max value_min value_max wearable
name id group wearable edit_group id group wearable id group wearable id group wearable value_min value_max

>cat file | awk '{ delete a; for (i=1; i<=NF; i++) a[$i]++; n=asorti(a, b); for (i=1; i<=n; i++) printf b[i]" "; print "" }'
camera_angle camera_distance camera_elevation edit_group edit_group_order group id label label_max label_min name value_max value_min wearable 
clothing_morph edit_group group id label name value_default value_max value_min wearable 
camera_angle camera_distance clothing_morph edit_group edit_group_order group id label label_max label_min name show_simple value_max value_min wearable 
clothing_morph edit_group group id label name value_default value_max value_min wearable 
camera_angle camera_distance camera_elevation clothing_morph edit_group edit_group_order group id label label_max label_min name value_max value_min wearable 
edit_group group id label label_max label_min name value_max value_min wearable 
edit_group group id name value_max value_min wearable

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

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