Remove/Add Comment from config file using sed [duplicate]
Something like this would work:
sed '/^#/{s/^#//;b};/./s/^/#/' infile
more readable:
sed '
/^#/ { # If a line starts with "#"
s/^#// # Remove the leading "#"
b # Move to next line
}
/./s/^/#/ # If the line is not empty, prepend "#"
' infile