UNIX Command Line

Input file: 

$ cat test.txt

one two three       four

1   2 3  4

i     ii   iii           iv

Sed code to delete/remove one or more space from a file. (Basically combine one or more space to a single space)

$ sed 's/[ \t]\+/ /g' test.txt > test.txt.1

$ cat test.txt.1

one two three four

1 2 3 4

i ii iii iv