sed and tr
Options
-i makes an edit in-place. -i.bak will make an edit in-place, but create a backup file w/ suffix .bak
Quick reference
Replace text in all files in & under the current directory
find . -type f -exec sed -i 's/old/new/g' {} \;
tr
Because sed works upon newlines, it makes it difficult to actually process newlines. Use tr instead.
# Remove all newlines
tr -d '\n'
# Replace space w/ newlines
tr -s '[[:space:]]' '\n'
# Replace newlines w/ space
tr '\n' ' '
