Replacing first occurence in every line

Question

Supposing I have a document formatted like this:

word1 word2 word3
word4 word5 word6
word7 word8

How do I use sed to replace the f

Answer 1

Using awk

awk '{sub(/ /,", ")}1' file
word1, word2 word3
word4, word5 word6
word7, word8

Answer 2

sed 's/\([^[:blank:]]\{1,\}\)/\1,/' YourFile

Add a , after first block of "non space", so start of line could be starting with space, it still work and also if line is without work but only with space (no , in this case)

Answer 3

Simple:

sed -i 's/ /, /' your_file

This looks for the first occurrence of a space, replaces it with a comma and space, then moves to the next line.

Answer 4

how about:

sed -e 's/\s\+/, /'

output:

word1, word2 word3
word4, word5 word6
word7, word8

Answer 5

echo FRIEND TOO MUCH |sed 's/ /, /'

FRIEND, TOO MUCH

Answer 6

echo word1 word2 word3|sed -r 's/(\s)/,\1/'

output:

word1, word2 word3